Co-reporter:Lihua Zhang;Yuhong Ma;Changwen Zhao;Bin He;Xing Zhu
Industrial & Engineering Chemistry Research June 8, 2016 Volume 55(Issue 22) pp:6354-6364
Publication Date(Web):Publication Date (Web): May 23, 2016
DOI:10.1021/acs.iecr.6b00254
Enzyme immobilization is a core technique of enzymatic biochemical engineering because it can remarkably reduce the cost of enzymes and improve the enzyme recovery procedure. The most crucial issues for enzyme immobilization include (1) maintaining its activity, both in the immobilization process and in the batchwise catalyst course; (2) separating the immobilized enzyme from the reaction mixture; and (3) the readiness and cost of the immobilization process. Herein, we report a new strategy to immobilize xylanase within a hydrophilic and nonswelling polyethylene glycol (PEG) net-cloth grafted on a polypropylene nonwoven fabric (PPNWF) membrane by a visible light-induced surface graft cross-linking polymerization. The xylanase was in situ entrapped within the PEG net-cloth. The nonswelling PEG net-cloth can effectively maintain the xylanase without leakage in long-term operation. As for the hydrolysis of corncob hemicelluloses, the experimental results showed that the as-formed immobilized xylanase retained 80% of its original activity after being reused for 25 cycles and 60% after 50 cycles, which is far better than that of other immobilization methods by entrapment. Notably, this simple in situ entrapment of enzymes on routine polymeric matrix would lead to an easy industrial production at low cost, while the form of end-products as a sheet can be readily separated from the reaction mixture and reused for batchwise production. After immobilization, the xylanase showed no significant shift in pH or temperature optima as compared with its free form. These results suggest that the immobilization of xylanase within the PEG net-cloth grafted on PPNWF is promising for industrial applications because of its long-term operation stability and convenient recovery for reuse.
Co-reporter:Xing Zhu, Bin He, Changwen Zhao, Yuhong Ma, and Wantai Yang
Langmuir June 6, 2017 Volume 33(Issue 22) pp:5577-5577
Publication Date(Web):May 17, 2017
DOI:10.1021/acs.langmuir.7b00594
The use of the mixed catalytic system with several enzymes can provide multiple benefits in terms of the cost, simplification of a multistep reaction, and effectiveness of complex chemical reactions. Although study of different enzyme coimmobilization systems has attracted increasing attention in recent years, separately immobilizing enzymes which can not coexist on one support is still one of the great challenges. In this paper, a simple and effective strategy was introduced to separately encapsulate incompatible trypsin and transglutaminase (TGase) into different poly(ethylene glycol) (PEG) network layer grafted on low-density polyethylene (LDPE) film via visible light induced living photografting polymerization. As a proof of concept, this dual-enzyme separately loaded film was used to catalyze the synthesis of a new target antitumor drug LTV-azacytidine. The final results demonstrated that this strategy could maintain higher activities of both enzymes than the mixed coimmobilization method. And the mass spectra analysis results demonstrated that LTV-azacytidine was successfully synthesized. We believe that this facile and mild separately immobilizing incompatible enzyme strategy has great application potential in the field of biocatalysis.
Co-reporter:Yanjiao Lu;Meizhen Yin
Industrial & Engineering Chemistry Research February 26, 2014 Volume 53(Issue 8) pp:2872-2877
Publication Date(Web):2017-2-22
DOI:10.1021/ie403211f
Fluorescent silica-doped polyvinylpyrrolidone (PVP) composites with high optical properties have been successfully prepared in a one-pot synthesis through the incorporation of silica nanoparticles and dye molecules into the cross-linked PVP. Scanning electron microscopy, transmission electron microscopy, and fluorescence spectrometry are used to investigate the morphologies and optical properties of the composites. By adjusting the PVP content and reaction time, fluorescent silica-doped PVP film and fluorescent PVP-covered silica core–shell nanoparticles are obtained without stirring and under magnetic stirring, respectively. Because both the silica nanoparticles and the dye molecules react with ring-opened PVP, the composites exhibit highly stable optical properties. The obtained fluorescent composites may have potential applications in sensing and photovoltaic systems. The facile approach can be extended to the preparation of multifunctional fluorescent PVP composites by introducing other types of oxides.
Co-reporter:Xu Yan;Lihua Zhang;Qian Liu;Guan Wang;Xiaofei Liu
Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 41) pp:6356-6361
Publication Date(Web):2017/10/24
DOI:10.1039/C7PY01329A
A novel redox reaction system consisting of xanthone (XT) and N-hydroxyphthalimide (NHPI) for radical polymerization is developed where NHPI and XT experience a one-electron-transfer reaction, which produces two kinds of radicals, PINO radicals and cycloketyl (CK) radicals. This redox system is efficient to initiate the radical polymerization of three typical monomers, i.e., methyl methacrylate (MMA), butyl acrylate (BA) and styrene, and the analytical results of the end-groups by NMR and MALDI-TOF MS demonstrate that PINO radicals initiate the polymerization, while CK radicals act as dormant radicals. As the polymerization proceeds, a significant increase in molecular weight and a decrease in PDI are observed, which could be attributed to the reversible deactivation between CK radicals and polymer chain radicals.
Co-reporter:Wenchao Ma;Xianhong Zhang;Yuhong Ma;Dong Chen;Li Wang;Changwen Zhao
Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 23) pp:3574-3585
Publication Date(Web):2017/06/13
DOI:10.1039/C7PY00408G
A photo-induced controlled radical polymerization of methacrylates with perfluoro-1-iodohexane as an initiator and benzaldehyde derivatives, including p-anisaldehyde, p-cyanobenzaldehyde and 2,4-dimethoxy benzaldehyde, as organic photocatalysts is demonstrated by using 23 W compact fluorescent lamps as the light source in the presence of a potential reductant N,N-dimethylaniline. Linear evolution of the molecular weight with monomer conversion is observed under the optimized conditions. Additionally, successful chain extension reactions are obtained by a one-pot process and with the as-prepared polymers as macroinitiators. Specifically, the one-pot synthesis of PPEGMA (conversion = 85%) with a high molecular weight and relatively narrow molecular weight distribution (Mn,GPC = 44 000 g mol−1, PDI = 1.54) is achieved by using PPEGMA-I (Mn,GPC = 10 200 g mol−1, PDI = 1.33) as a macroinitiator and p-anisaldehyde as an organocatalyst. Although the current technology exhibits a somewhat low controllability for preparing block copolymers, compared with the common ATRP and RAFT polymerization process, it offers a promising alternative as a metal-free organo-catalyzed photo-induced variant of ATRP.
Co-reporter:Dong Chen;Yang Liu;Yan Qin;Li Wang;Yuhong Ma
Chinese Journal of Chemistry 2017 Volume 35(Issue 5) pp:596-604
Publication Date(Web):2017/05/01
DOI:10.1002/cjoc.201600681
AbstractIn the present work, novel dual-functionalized hollow polymer particles (DF-HPP) with high density of carboxylate and amino dual functional groups have been specially designed and fabricated to serve as high-performance adsorbent for selective removal of basic dye (methylene blue, b-MB, as a model dye). Due to both the high surface area and the extremely high density of carboxylate and amino groups, the DF-HPPs exhibited excellent adsorption property for methylene blue (b-MB), including high adsorption capacity, fast adsorption/desorption rates, unique pH-sensitivity and easy recovery. The equilibrium adsorption data of b-MB on the DF-HPPs were evaluated using Freundlich and Langmuir isotherm models, and the equilibrium isotherm was better fit with Langmuir model with a maximum adsorption capacity of 538.8 mg/g at pH 12. More interestingly, the DF-HPPs showed a significant pH-dependent equilibrium adsorption capacity, which decreased dramatically from 516.1 mg/g to 24 mg/g as the solution pH decreased from 12 to 3. The dye-adsorbed DF-HPPs can be facilely and rapidly regenerated under mild condition (under weak acidic solution, pH 3, in 30 min) to recover both b-MB and the DF-HPPs, and the regenerated DF-HPPs can be reused for dye removal with high efficiency, indicating the exceptional recyclability of the DF-HPPs.
Co-reporter:Kun Jiang;Yanan Liu;Yaping Yan;Shengliu Wang;Lianying Liu
Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 8) pp:1404-1416
Publication Date(Web):2017/02/21
DOI:10.1039/C6PY02094A
Simple and convenient synthetic methods are highly in demand for the preparation and application of patchy particles (PPs) with diverse morphologies, functionalities and behaviors. Very recently, step-growth heterogeneous click polymerizations have been developed to fabricate monodisperse, spherical, soft and clickable particles. However, so far, this technique has seldom involved forming structures (core–shell, or pores, etc.), anisotropic shapes and compositions of particles. Herein, we prepare PPs with a hard body and soft, clickable dimple- or bulge-patches by incorporating step-growth thiol–ene polymerizations into the chain-growth polymerization of styrene (St) in a dispersion system. The phase separation between thiol–ene polymers and PSt in growing particles occurs due to their differences in the glass transition temperature (Tg) and hydrophilicity, forming core–shell and dimple- or bulge-patched particles. SEM and TEM images of the degraded particles confirm that the patches are primarily composed of click polymers. Varying the addition time, amounts, feed ratio and type of thiol/ene monomer, degree of phase separation, shape, number and size of patches, and contents of thiol/ene segments in/on patches are tuned flexibly. FI-IR analyses reveal that off-stoichiometric thiol and ene segments are incorporated, owing to off-stoichiometric thiol–ene reactions concurrent with the polymerization of St, even when stoichiometric thiol and ene are added. Moreover, Fe3O4 or Ag nanoparticles are attached on the PSt body with –SO3− groups or on click polymer patches with –SH groups. Post-modifications of PPs are carried out through reactions of excess –SH or –CC– groups on patches with –CC– or –SH group-containing monomers. Superhydrophobic or hydrophilic particulate films, or fluorescent tagged PPs are prepared.
Co-reporter:Dong Chen, Li Wang, Yuhong Ma and Wantai Yang
NPG Asia Materials 2016 8(8) pp:e301
Publication Date(Web):2016-08-01
DOI:10.1038/am.2016.117
Porous polymer particles with multilevel structures consisting of submicron-sized hollow cavities and interconnected mesopores within the crosslinked shell were designed and prepared. An extremely high density of anhydride groups in the crosslinked shell can be conveniently converted into versatile functional groups for the adsorption of hazardous pollutants. As a proof of concept, we utilized carboxylate-functionalized hollow particles as a selective adsorbent for the removal of the basic dye methylene blue and found that these particles exhibited a very high adsorption capacity (1603 mg g−1). Furthermore, the hollow structure, highly interconnected mesopores and rigid shell of the particles not only endow the adsorbent with fast adsorption/desorption rates but also facilitate their facile separation and easy regeneration. We believe that these porous polymer particles have great potential for applications in many fields, including as adsorbents, catalyst supports and matrices for the binding of sensitive materials.
Co-reporter:Yan Qin, Li Wang, Changwen Zhao, Dong Chen, Yuhong Ma, and Wantai Yang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 26) pp:16690-16698
Publication Date(Web):June 15, 2016
DOI:10.1021/acsami.6b04199
In this work, a novel type of ammonium-functionalized hollow polymer particles (HPP-NH3+) with a high density of ammonium groups in the shell has been specially designed and synthesized. Benefiting from both the high surface area and from the high density of positively charged ammonium groups, the as-prepared HPP-NH3+ can serve as a selective adsorbent for the removal of negatively charged acid dye (e.g., methyl blue a-MB). The equilibrium adsorption data of a-MB on the HPP-NH3+ were evaluated using Freundlich and Langmuir isotherm models, and Langmuir isotherm exhibited a better fit with a maximum adsorption capacity of 406 mg/g. Most importantly, because of the presence of dual functional groups (ammonium and carboxyl groups), the HPP-NH3+ showed a significant pH-dependent equilibrium adsorption capacity, which increased dramatically from 59 mg/g to 449 mg/g as the solution pH decreased from 9 to 2. This uniqueness makes the dye-adsorbed HPP-NH3+ can be facilely regenerated under mild condition (in weak alkaline solution, pH 10) to recover both a-MB and the HPP-NH3+, whereas the recovery of conventional adsorbents is commonly performed under particularly severe conditions. The regenerated HPP-NH3+ can be reused for dye removal and the dye removal efficiency remained above 98% even after five adsorption–desorption cycles. Because of its high adsorption capacity, pH-sensitivity, easy regeneration, and good reusability, the HPP-NH3+ has great potential for the application in the field of water treatment, controlled drug release, and pH-responsive delivery.
Co-reporter:Yanan Liu, Kun Jiang, Yuhong Ma, Lianying Liu and Wantai Yang
Polymer Chemistry 2016 vol. 7(Issue 15) pp:2728-2739
Publication Date(Web):24 Mar 2016
DOI:10.1039/C6PY00218H
Previously, it was a challenge to develop a direct and convenient synthetic means for production of anisotropic particles, formation of structures (core–shell, cavity, hollow, etc.) and functionalization of domains all at once. Herein, we present a simple one-step dispersion polymerization (Dis.P) approach to synthesize particles with a combination of anisotropies in morphology, surface roughness, structure and composition. This approach needs no delayed addition of agents, and is of comparable simplicity to the preparation of conventional spherical particles. A cross-linker of dimethacryloyloxybenzophenone (DMABP) is added at the beginning of Dis.P of styrene (St). Evolution of monomer conversion, particle gel content and morphology during Dis.P indicates that DMABP is consumed early and rapidly, creating a high cross-linking of a growing particle at a low conversion, thus inducing phase separation and producing snowman- or dumbbell-like particles which contain a firstly cross-linked, coarse growing particle domain (G domain) and an uncross-linked or subsequently cross-linked, smooth, new domain (N domain). The size, surface roughness, structure and composition of the domains are tuned by initially adding various amounts of DMABP and a low amount of functional monomers. Due to the quick reaction of hydrophilic 4-vinylpyridine (4-VP), glycidyl methacrylate (GMA) or methacrylic acid (MAA), the G domain is enriched with pyridyl, epoxy or carboxyl groups, as detected by XPS and EDS. Through the delayed reaction of monomers containing alkynyl groups (–CC–), the N domain is enriched with –CC– groups, and the core–shell (cross-linked) structure is formed. With aids of thiols added during Dis.P, SH– or fluorine-containing groups are primarily incorporated on the N domain, and the porous, cavity or hollow structure of the N domain is generated due to phase separation between polystyrene (PSt) and the polymer produced by the click reaction. On adding two functional monomers (MAA and monomer containing –CC– groups), various functional groups enrich G and N domains, respectively, owing to the sequential reactions of monomers.
Co-reporter:Wenchao Ma, Dong Chen, Yuhong Ma, Li Wang, Changwen Zhao and Wantai Yang
Polymer Chemistry 2016 vol. 7(Issue 25) pp:4226-4236
Publication Date(Web):01 Jun 2016
DOI:10.1039/C6PY00687F
With ethyl-α-bromophenylacetate (EBPA) as an initiator and Cu(dap)2Cl (dap = 2,9-bis(p-anisyl)-1,10-phenanthroline) as a photoredox catalyst, controlled radical polymerizations of poly(ethylene glycol)methyl ether methacrylate (PEGMA) and methyl methacrylate (MMA) are demonstrated under LED light lamp irradiation (4500 μW cm−2@420 nm). The catalysis cycles proceed in the presence of N,N-dimethylaniline (DMA) or tris[2-(dimethylamino)ethyl]amine (Me6TREN), which could serve as reductants to regenerate a Cu(I) complex from the oxidized Cu(II) complex. In addition, Me6TREN plays another important role as an efficient ligand for the copper-based photopolymerization of methacrylate monomers. Good linear evolution of molecular weight (Mn) with monomer conversion is observed under the optimized conditions. Specifically, with [PEGMA]:[EBPA]:[Cu(dap)2Cl]:[Me6TREN] = 31:1:0.015:(0.15–0.45), poly(PEGMA) (PPEGMA) with polydispersity indexes (PDI) as low as 1.15 are obtained. To further verify the living nature of this system, block copolymers of PPEGMA-b-PMMA with high molecular weights and narrow molecular weight distributions (Mn,GPC = 59200 g mol−1, PDI = 1.28 and Mn,GPC = 93700 g mol−1, PDI = 1.44, respectively) are prepared using PPEGMA-Br (Mn,GPC = 11600 g mol−1; PDI = 1.13) as a macroinitiator. The polymers produced with Cu(dap)2Cl/Me6TREN as a catalyst and the PMMA obtained with Cu(dap)2Cl/DMA as a catalyst are colorless which is different from the heterogeneously catalyzed ATRP for its notorious Cu metal residue.
Co-reporter:C. R. Yao, L. Wang and W. T. Yang
RSC Advances 2016 vol. 6(Issue 74) pp:69743-69747
Publication Date(Web):12 Jul 2016
DOI:10.1039/C6RA14396B
Cycloketyl radical mediated living polymerization (CMP) was applied in the suspension polymerization of styrene (St). The polymerization behavior mediated by 9,9′-bixanthydrol (BIXANDL) both in the absence and presence of a traditional thermal initiator benzoyl peroxide (BPO) was investigated thoroughly. The results show that BIXANDL can initiate the suspension polymerization of St effectively and exert moderate control over molecular weights which grew linearly as St conversion increased. When BIXANDL was utilized along with BPO, the polymerization rate was enhanced and larger increases in chain length with increasing conversions were observed.
Co-reporter:Wenchao Ma;Dong Chen;Lianying Liu;Yuhong Ma;Li Wang;Changwen Zhao
Journal of Polymer Science Part A: Polymer Chemistry 2016 Volume 54( Issue 6) pp:740-749
Publication Date(Web):
DOI:10.1002/pola.27906
ABSTRACT
A new strategy is developed to prepare both α,ω-dithiol and α,ω-divinyl linear telechelic polythiolether oligomers by visible light induced thiol-ene chemistry in the presence of a fac-Ir(ppy)3 photoredox catalyst. Polythiolether oligomers of well-defined end groups and controlled molecular weights have been successfully synthesized at varying monomer molar ratios of 1,4-benzenedimethanethiol (BDMT) to diethylene glycol divinyl ether (DEGVE). 1H NMR and MALDI-TOF MS analyses demonstrate that as-prepared polythiolethers possess high end-group fidelity, which is further supported by the successful polyaddition of polythiolethers bearing α,ω-dithiol and α,ω-divinyl groups. For example, with the α,ω-dithiol- (Mn = 1900 g mol−1, PDI = 1.25) and α,ω-divinyl-terminated (Mn = 2000 g mol−1, PDI = 1.29) polythiolethers as macromonomers, the molecular weight of resulting polythiolether is up to 7700 g mol−1 with PDI as 1.67. The reactivity of the terminal thiol group is further confirmed by the addition reaction with N-(1-pyrenyl)maleimide. UV-vis spectra and fluorescene measurements suggest that fac-Ir(ppy)3 undergo a redox quenching process reacted with BDMT to generate thiyl free radicals. With these results, the mechanism of the thiol-ene reaction catalyzed by photoredox catalyst is proposed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 740–749
Co-reporter:Lihua Zhang, Yuhong Ma, Changwen Zhao, Xing Zhu, Ruichao Chen and Wantai Yang
Journal of Materials Chemistry A 2015 vol. 3(Issue 39) pp:7673-7681
Publication Date(Web):10 Aug 2015
DOI:10.1039/C5TB01149C
A new visible light induced graft polymerization method was utilized to prepare pH-sensitive hydrogel layers covalently attached to polymer substrates for drug delivery. In our strategy, isopropyl thioxanthone semi-pinacol (ITXSP) dormant groups were firstly introduced on the surface of a polycaprolactone (PCL) film by a UV-induced abstracting hydrogen-coupling reaction. Then visible light induced graft cross-linking polymerization was performed to initiate polymerization of poly(ethylene glycol) diacrylate (PEGDA) and acrylic acid (AA), resulting in the formation of a hydrogel layer. The thickness of the hydrogel film can be controlled by varying the exposure time and monomer composition. The grafted hydrogel layers showed a flat morphology and dense structure, which is different from the traditional reported porous structure. The water contact angle of the hydrogel layer exhibited a reversible change from 38° to 18° when the film was alternatively treated in buffers of pH 2.0 and 7.4, respectively. Patterned hydrogel layers were prepared as a model to determine the change in the height of the grafted hydrogel layer as a function of pH. As the pH changed from 2.0 to 7.4, the hydrogel pattern showed an increase in height due to the swelling of the hydrogel network, and the hydrogel layer formed by 0.2 wt% PEGDA and 25 wt% AA showed the most increase (30%) in height. Bovine serum albumin (BSA) and lysozyme as models of protein drugs were incorporated in the hydrogel network, and their release also showed obvious pH-sensitivity. At pH 2.0, hydrogels present a faster initial burst release due to the squeezing mechanism. Tertiary structure analysis showed that encapsulation and release did not affect the protein conformation. These findings have improved our understanding of hydrogel thin films, which may be useful as potential vehicles of therapeutic proteins in drug delivery applications.
Co-reporter:Xianguang Huang, Li Wang and Wantai Yang
Polymer Chemistry 2015 vol. 6(Issue 37) pp:6664-6670
Publication Date(Web):04 Aug 2015
DOI:10.1039/C5PY00703H
A simple and novel synthetic route toward core–shell polymeric particles via surface-initiated cycloketyl radical mediated living polymerization (CMP) is presented. Cross-linked polymaleic anhydride/isoprene particles (CPMIP) prepared by self-stable precipitation polymerization were reacted with 9,9′-bixanthydrol (BIXANDL), which endowed them with potential initiating sites for subsequent CMP of styrene, methyl methacrylate and n-butyl acrylate. Uniform core–shell particles were successfully obtained in all cases and their sizes increased with continuous monomer conversion, demonstrating the versatility and living feature of surface-initiated CMP.
Co-reporter:Teng Wang, Xianhong Zhang, Dong Chen, Yuhong Ma, Li Wang, Changwen Zhao, Wantai Yang
Applied Surface Science 2015 Volume 356() pp:232-239
Publication Date(Web):30 November 2015
DOI:10.1016/j.apsusc.2015.08.077
Highlights
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Core–shell structured BaTiO3@PEDOT nanocomposite.
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High performance BaTiO3@PEDOT/PVDF dielectric composite.
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High specific capacitance BaTiO3@PEDOT nanocomposite.
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Conductive BaTiO3@PEDOT nanocomposite.
Co-reporter:Zhuo Li, Li Wang, Yu-Hong Ma, Wan-Tai Yang
Chinese Chemical Letters 2015 Volume 26(Issue 11) pp:1351-1354
Publication Date(Web):November 2015
DOI:10.1016/j.cclet.2015.06.018
Polypropylene/poly(butyl acrylate) alloy is produced by water–solid phase suspension grafting polymerization with a submicrometer microdomain where graft polymerization occurs within micropores of polypropylene particles prepared by reactor granule technology (RGT). The results show that the grafting percentage (GP) of butyl acrylate (BA) increases with the increase of the monomer concentration, which could reach 32.6% while the grafting efficiency (GE) is up to 98%. The addition of the crosslinking agent, triethylene glycol diacrylate (TEGDA), could improve GP up to 36.3%. Transmission electron microscopic (TEM) micrographs demonstrate that PBA microdomains distributed in PP matrix increase in size less than 500 nm. Moreover, TEM images show that the grafting phase exhibits a single-phase behavior with the addition of TEGDA, which implies that the ratio of graft copolymer increased.The addition of the crosslinking agent, triethylene glycol diacrylate (TEGDA), could improve grafting percentage up to 36.3%. Moreover, TEM images show that the grafting phase exhibits a single-phase behavior with the addition of TEGDA, which supports the increased ratio of graft copolymer.
Co-reporter:Yan Zhou;Li Wang;Yuhong Ma;Dong Chen;Changwen Zhao
Journal of Applied Polymer Science 2015 Volume 132( Issue 36) pp:
Publication Date(Web):
DOI:10.1002/app.42508
ABSTRACT
Flexible layer–layer poly(ethylene phthalate) (PET)/BaTiO3 composite films with enhanced dielectric permittivity were fabricated by spin coating method, consisting of PET substrate film layer and modified BaTiO3/acrylic resin hybrid coating layer. The thickness of coating layer was less than 3 μm (about 2% of PET film thickness), and therefore, the PET/barium titanate (BT) composite films remained flexible even at high volume fraction of BaTiO3 fillers. The volume contents of BaTiO3 were varied from 0 to 80%, and the solid contents of BaTiO3/acrylic resin were in the range of 51.8–72.9%. Scanning electron microscopy showed strong interaction of finely dispersed BaTiO3 particles with acrylic resin. Morphological profile also displayed uniform coating layer of modified BaTiO3/acrylic resin and its strong adhesion with PET film. The dielectric constant of the PET/BaTiO3 composite films increased by about 26% at 60 vol % BaTiO3 loading when compared with the pristine PET film, whereas the dielectric loss decreased slightly. In addition, PET-grafted poly(hydroxylethyl methacrylate) brushes were used as substrate to introduce covalent bonding with the coating layer. Further enhancement of dielectric constant and reduction of dielectric loss were realized when compared with the composite films with bare PET substrate. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42508.
Co-reporter:Qian Liu;Lianying Liu;Yuhong Ma;Changwen Zhao
Journal of Applied Polymer Science 2015 Volume 132( Issue 7) pp:
Publication Date(Web):
DOI:10.1002/app.41460
ABSTRACT
A new polymer chain growth mode, having multiple potential chain propagation sites, initiated by oligomer of α-methylstyrene (AMS) and styrene (St) (PAS) is presented in this article. The effects of PAS content, AMS fraction in PAS and reaction temperature on bulk polymerization of St have been investigated. It is demonstrated that the PAS performed as macroinitiator in the polymerization of St. The average molecular weights of products increase significantly with the evolution of the polymerization, which is different from conventional free radical polymerization. With 20 wt % macroinitiator, the molecular weights increase from 1.21 × 105 to 3.00 × 105 with the monomer conversion increasing from 15.3 to 83.0%. This unique feature is tentatively attributed to both the reversible polymerization–depolymerization of AMS segments at high temperature which could generate more than one propagation sites in a polymer chain and the combination termination of St free radical polymerization. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41460.
Co-reporter:Yuhong Ma;Shan Jiang;Shujun Liang
Macromolecular Reaction Engineering 2015 Volume 9( Issue 5) pp:490-502
Publication Date(Web):
DOI:10.1002/mren.201400059
In textbooks, there is a dynamic equilibrium between the monomer α-methylstyrene (AMS) and its polymer (PAMS) when the temperature is greater than 61 °C. When giving these phenomena deliberate thought we come to the basic conclusion that there probably exists a dynamic equilibrium between fragmentation and coupling of polymeric chains by a radical mechanism when heated. Thus, a systematic exploration of the synthesis of AMS copolymers as potential sources of chain radicals has been carried out in our laboratory. This paper reviews the results we have achieved in the past decade: (1) The preparation of various AMS copolymers including (meth) acrylate, acrylic acid, styrene, and maleic anhydride. (2) The application of copolymers containing AMS structural units as very efficient free radical initiators. (3) The preparation of various functional copolymers including block copolymers and core-shell polymer particles with AMS copolymers as macroinitiators. (4) The steady increase of the molecular weight of the copolymer with the monomer conversion for some systems, which is characteristic of living polymerization. (5) The finding that AMS copolymers with functional groups can act as in situ compatibilizers through the formation of graft polymers, and that AMS copolymers can be used to modify MWCNTs by a free radical grafting-onto mechanism.
Co-reporter:Yanan Liu, Wang Liu, Yuhong Ma, Lianying Liu, and Wantai Yang
Langmuir 2015 Volume 31(Issue 3) pp:925-936
Publication Date(Web):December 30, 2014
DOI:10.1021/la504317m
Previously, synthesis of anisotropic particles by seeded polymerizations has involved multiple process steps. In conventional one-pot dispersion polymerization (Dis.P) with a cross-linker added, only spherical particles are produced due to rapid and high cross-linking. In this Article, a straightforward one-pot preparation of monodisperse anisotropic particles with tunable morphology, dimensions, surface roughness, and asymmetrically distributed functional groups is described. With a cross-linker of divinylbenzene (DVB, 8%), ethylene glycol dimethacrylate (EGDMA, 6%), or dimethacryloyloxybenzophenone (DMABP, 5%) added at 40 min, shortly after the end of nucleation stage in Dis.P of styrene (St) in methanol and water (6/4, vol), the swollen growing particles are inhomogeneously cross-linked at first. Then, at low gel contents of 59%, 49%, and 69%, corresponding to the cases using DVB, EGDMA, and DMABP, respectively, the growing particle phase separates and snowman- or dumbbell-like particles are generated. Thermodynamic and kinetic analyses reveal that moderate cross-linking and sufficient swelling of growing particles determine the formation and growth of anisotropic particles during polymerization. Morphology, surface roughness, sizes, and cross-linking degrees of each domain of final particles are tuned continuously by varying start addition time and contents of cross-linkers. The snowman-like particles fabricated with DVB have a gradient cross-linking and asymmetrical distribution of pendant vinyl groups from their body to head. The dumbbell-like particles prepared using DMABP have only one domain cross-linked; i.e., only one domain contains photosensitive benzophenone (BP) groups. With addition of glycidyl methacrylate (GMA) or propargyl methacrylate (PMA) together with DVB or EGDMA, epoxy or alkynyl groups are asymmetrically incorporated. With the aid of these functional groups, carboxyl, amino, or thiol groups and PEG (200) are attached by thiol–ene (yne) click and photocoupling reactions.
Co-reporter:Yanan Liu;Qing Yang;Jinmei Zhu;Lianying Liu
Colloid and Polymer Science 2015 Volume 293( Issue 2) pp:523-532
Publication Date(Web):2015 February
DOI:10.1007/s00396-014-3444-0
Preparation of anisotropic particles based on phase separation of prefabricated seeds in polymerizations generally involves multiple process steps. In conventional one-pot dispersion polymerization, only spherical particles are produced. Herein, anisotropic particles with asymmetrical core-shell structure, multiple compartments, and continuously tunable surface roughness and sizes were synthesized by a modified one-pot dispersion polymerization. A mixture of polar solvents, ethylene glycol (EG), and water (6/4, vol.) was used as medium for polymerization of styrene (St). In the presence of ammonium persulfate (APS) and vinyl acetate (VA), divinylbenzene (DVB, 16.1–66.4 %) and (St, 50.3–0 %) were added at 60, 180, and 360 min, respectively. Dense cross-linking was confined to exterior of swollen growing particles, resulting in phase separation and formation of snowman-like particles with coarse, core-shell structured body, and smooth, no or partially cross-linked head. The newly formed compartments were also inhomogeneously cross-linked and their phases separated, producing three and four compartment anisotropic particles with an aspect ratio up to 2.3. Gel content of final particles was less than 75 %. Due to a sequential cross-linking from growing particle to newly formed compartments, reaction stability and particle monodispersity were maintained even when high amounts of DVB were added. Asymmetrical morphologies, structures, sizes, and surface roughness of particles were continuously tuned by varying DVB amount and its start addition time. This one-pot method provides a simple, efficient route for synthesis of anisotropic particles.
Co-reporter:Zhuo Li;Yu-hong Ma;Wan-tai Yang 杨万泰
Chinese Journal of Polymer Science 2015 Volume 33( Issue 12) pp:1730-1740
Publication Date(Web):2015 December
DOI:10.1007/s10118-015-1716-x
Using the porous polypropylene (PP) granules consisting of submicroparticles prepared by the reactor granular technology (RGT), a facile process was developed to synthesize in situ polypropylene/silica nanocomposites where styrene-alt-maleic anhydride copolymers (PSM) were firstly grafted onto both the outer- and the inner-pore surfaces of PP granules via solid-phase grafting polymerization, and then a sol-gel reaction was conducted inside these micro-pores with the carboxyl acid derived from maleic anhydride as catalyst. TEM micrographs demonstrated that the silica nanoparticles obtained by this strategy had a size around 10-20 nm in diameter and uniformly dispersed in the PSM-based nanocomposites. More importantly, the silica nanoparticles could significantly reduce the size of PP spherulites. Consequently, the PP/silica nanocomposites with high transparency and good mechanical performance were achieved.
Co-reporter:Mengjiao Cheng;Feng Shi;Jianshu Li;Zaifu Lin;Chao Jiang;Meng Xiao;Liqun Zhang;Toshio Nishi
Advanced Materials 2014 Volume 26( Issue 19) pp:3009-3013
Publication Date(Web):
DOI:10.1002/adma.201305177
Co-reporter:Peng Yang and Wantai Yang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 6) pp:3759
Publication Date(Web):February 24, 2014
DOI:10.1021/am405857m
It may be hardly believable that inert C–H bonds on a polymeric material surface could be quickly and efficiently transformed into C–OH by a simple and mild way. Thanks to the approaches developed recently, it is now possible to transform surface H atoms of a polymeric substrate into monolayer OH groups by a simple/mild photochemical reaction. Herein the method and application of this small-molecular interfacial chemistry is highlighted. The existence of hydroxyl groups on material surfaces not only determines the physical and chemical properties of materials but also provides effective reaction sites for postsynthetic sequential modification to fulfill the requirements of various applications. However, organic synthetic materials based on petroleum, especially polyolefins comprise mainly C and H atoms and thus present serious surface problems due to low surface energy and inertness in reactivity. These limitations make it challenging to perform postsynthetic surface sequential chemical derivatization toward enhanced functionalities and properties and also cause serious interfacial problems when bonding or integrating polymer substrates with natural or inorganic materials. Polymer surface hydroxylation based on direct conversion of C–H bonds on polymer surfaces is thus of significant importance for academic and practical industrial applications. Although highly active research results have reported on small-molecular C–H bond activation in solution (thus homogeneous), most of them, featuring the use of a variety of transition metals as catalysts, present a slow reaction rate, a low atom economy and an obvious environmental pollution. In sharp contrast to these conventional C–H activation strategies, the present Spotlight describes a universal confined photocatalytic oxidation (CPO) system that is able to directly convert polymer surface C–H bonds to C–OSO3– and, subsequently, to C–OH through a simple hydrolysis. Generally speaking, these newly implanted hydroxyl groups preserve their own reactivity toward other complementary compounds, thus creating a novel base with distinct surface properties. Thanks to this functionalized platform, a wide range of organic, inorganic and metal materials have been attached to conventional organic polymer substrates through the rational engineering of surface molecular templates from small functional groups to macromolecules. It is expected that the proposed novel CPO method and its versatile usages in advanced material applications will offer new opportunities for a variety of scientific communities, especially for those working on surface/interface modulation.Keywords: hydroxylation; organic−inorganic hybrid material; patterning; photochemical reaction; polymer functionalization; Surface modification;
Co-reporter:Zhifeng Lin, Yuhong Ma, Changwen Zhao, Ruichao Chen, Xing Zhu, Lihua Zhang, Xu Yan and Wantai Yang
Lab on a Chip 2014 vol. 14(Issue 14) pp:2505-2514
Publication Date(Web):14 Apr 2014
DOI:10.1039/C4LC00223G
Protein microarrays have become vital tools for various applications in biomedicine and bio-analysis during the past decade. The intense requirements for a lower detection limit and industrialization in this area have resulted in a persistent pursuit to fabricate protein microarrays with a low background and high signal intensity via simple methods. Here, we report on an extremely simple strategy to create three-dimensional (3D) protein microarrays with an anti-fouling background and a high protein capacity by photo-induced surface sequential controlled/living graft polymerization developed in our lab. According to this strategy, “dormant” groups of isopropyl thioxanthone semipinacol (ITXSP) were first introduced to a polymeric substrate through ultraviolet (UV)-induced surface abstraction of hydrogen, followed by a coupling reaction. Under visible light irradiation, the ITXSP groups were photolyzed to initiate surface living graft polymerization of poly(ethylene glycol) methyl methacrylate (PEGMMA), thus introducing PEG brushes to the substrate to generate a full anti-fouling background. Due to the living nature of this graft polymerization, there were still ITXSP groups on the chain ends of the PEG brushes. Therefore, by in situ secondary living graft cross-linking copolymerization of glycidyl methacrylate (GMA) and polyethylene glycol diacrylate (PEGDA), we could finally plant height-controllable cylinder microarrays of a 3D PEG network containing reactive epoxy groups onto the PEG brushes. Through a commonly used reaction of amine and epoxy groups, the proteins could readily be covalently immobilized onto the microarrays. This delicate design aims to overcome two universal limitations in protein microarrays: a full anti-fouling background can effectively eliminate noise caused by non-specific absorption and a 3D reactive network provides a larger protein-loading capacity to improve signal intensity. The results of non-specific protein absorption tests demonstrated that the introduction of PEG brushes greatly improved the anti-fouling properties of the pristine low-density polyethylene (LDPE), for which the absorption to bovine serum albumin was reduced by 83.3%. Moreover, the 3D protein microarrays exhibited a higher protein capacity than the controls to which were attached the same protein on PGMA brushes and monolayer epoxy functional groups. The 3D protein microarrays were used to test the immunoglobulin G (IgG) concentration in human serum, suggesting that they could be used for biomedical diagnosis, which indicates that more potential bio-applications could be developed for these protein microarrays in the future.
Co-reporter:Xiaohu Wei;Graeme Moad;Benjamin W. Muir;Ezio Rizzardo;Julien Rosselgong;San H. Thang
Macromolecular Rapid Communications 2014 Volume 35( Issue 8) pp:840-845
Publication Date(Web):
DOI:10.1002/marc.201300879
Co-reporter:Xianhong Zhang, Yuhong Ma, Changwen Zhao, Wantai Yang
Applied Surface Science 2014 Volume 305() pp:531-538
Publication Date(Web):30 June 2014
DOI:10.1016/j.apsusc.2014.03.131
Highlights
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BaTiO3 Nanofiber was fabricated by electrospinning.
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The surface of BaTiO3 nanofiber was successfully modified by simple fluorosilane coupling.
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The compatibility of PVDF matrix and BaTiO3 nanofiber filler were greatly enhanced.
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The dielectric constant and dielectric loss tan δ of the composite were significantly improved.
Co-reporter:Ruichao Chen, Yuhong Ma, Changwen Zhao, Zhifeng Lin, Xing Zhu, Lihua Zhang and Wantai Yang
RSC Advances 2014 vol. 4(Issue 87) pp:46653-46661
Publication Date(Web):26 Sep 2014
DOI:10.1039/C4RA07442D
During recent research on the fabrication of DNA microarrays, polymers have been intensively investigated as substrates for immobilizing oligonucleotides, due to their low cost, disposability and excellent processing flexibility. Among these, cyclic olefin copolymers (COCs) are of special interest because of their many favorable properties, including high glass transition temperature, low auto-fluorescence, optical clarity and resistance to organic solvents. In the present study a novel strategy has been developed by introducing epoxy groups on the COC surface, based on a confined photocatalytic oxidation (CPO) method. Firstly, a sulfate anion (–SO4−) was introduced on to the COC film by CPO, accompanied by brief (120 s) UV irradiation. The sulfate anions were then hydrolyzed to form hydroxyl groups (–OH), forming a glass-like surface, which readily reacts with a silane coupling agent. In the present study (3-glycidoxypropyl)trimethoxysilane was used as a model for introducing epoxy groups on to COC film, the result confirmed by X-ray photoelectron spectroscopy (XPS), water contact angle measurement and atomic force microscopy (AFM). DNA probes were subsequently spotted on the COC surface and immobilized by reaction between the epoxy groups and amino groups on strands of DNA. The immobilization efficiency of different concentrations of DNA probes on the COC surface ranged from 45% to 65%, comparable to a traditional epoxy-functionalized glass slide. Hybridization with complementary strands of this microarray was successfully achieved, and the fluorescence intensity after hybridization was readily tuned by adjusting the probe immobilization density, or the target DNA sequence concentration in a hybridization solution. This simple approach has considerable potential in the construction of low-cost polymer biochips.
Co-reporter:Yanjiao Lu, Wantai Yang, Meizhen Yin
Materials Letters 2014 Volume 125() pp:4-7
Publication Date(Web):15 June 2014
DOI:10.1016/j.matlet.2014.03.118
•A facile one-pot method towards the construction of bifucntional magnetic-fluorescent polyvinylpyrrolidone (PVP) film.•The mechanism relies on the chemical reaction between the ring-opened PVP and the magnetic nanoparticles as well as the dye molecules.•The PVP film exhibits excellent superparamagnetism and high optical stability due to the covalent bonding of magnetic nanoparticles and the dye molecules.•The facile method could be extended to other oxides for the preparation of multi-functional composite PVP films.A facile one-pot method is developed to produce bifunctional magnetic-fluorescent polyvinylpyrrolidone (PVP) film with excellent superparamagnetism and stable optical property. The optical and magnetic properties and the morphology of the produced PVP film are investigated by fluorescence spectrometry, vibrating sample magnetometer and scanning electron microscopy. The magnetic nanoparticles and the dye molecules are incorporated into the PVP film networks through covalent linkages and the obtained magnetic-fluorescent PVP film exhibits highly stable superparamagnetism and fluorescent property. This facile preparation method can be extended to the fabrication of oxides-doped fluorescent PVP films.Schematic representation of the formation of magnetic-fluorescent PVP film.
Co-reporter:Mengmeng Sun;Yong He;Yong Ye;Meizhen Yin
Macromolecular Chemistry and Physics 2014 Volume 215( Issue 6) pp:493-498
Publication Date(Web):
DOI:10.1002/macp.201300688
Co-reporter:Zhenhua Huang;Zhengfang Wu;Dr. Peng Yang;Dr. Wantai Yang
Chemistry - A European Journal 2014 Volume 20( Issue 36) pp:11421-11427
Publication Date(Web):
DOI:10.1002/chem.201402786
Abstract
It is generally accepted that Ce4+ is unable to directly oxidize unreactive alkyl CH bonds without the assistance of adjacent polar groups. Herein, we demonstrate in our newly developed confined photochemical reaction system that this recognized issue may be challenged. As we found, when a thin layer of a CeCl3/HCl aqueous solution was applied to a polymeric substrate and the substrate subjected to UV irradiation, Ce3+ was first photooxidized to form Ce4+ in the presence of H+, and the in situ formed Ce4+ then performs an oxidation reaction on the CH bonds of the polymer surface to form surface-carbon radicals for radical graft polymerization reactions and functional-group transformations, while reducing to Ce3+ and releasing H+ in the process. This photoinduced cerium recycling redox (PCRR) reaction behaved as a biomimetic system in an artificial recycling reaction, leading to a sustainable chemical modification strategy for directly transforming alkyl CH bonds on polymer surfaces into small-molecule groups and polymer brushes. This method is expected to provide a green and economical tool for industrial applications of polymer-surface modification.
Co-reporter:Jian He;Dong Chen;Kai Han;Xiaoxia Huang;Liwei Wang;Jianyuan Deng
Journal of Polymer Science Part A: Polymer Chemistry 2014 Volume 52( Issue 20) pp:2894-2898
Publication Date(Web):
DOI:10.1002/pola.27339
Co-reporter:Yanning Chen;Dong Chen;Yuhong Ma
Journal of Polymer Science Part A: Polymer Chemistry 2014 Volume 52( Issue 8) pp:1059-1067
Publication Date(Web):
DOI:10.1002/pola.27099
ABSTRACT
The hydrophobic solid surface modification with fluorine-containing monomers has received tremendous attention because of its unique structure and excellent property. However, these hydrophobic films normally suffer from two major problems: one is weak interface interaction between fluoropolymers and substrates, and the other is the high cost of fluorine-containing monomers. Herein, with the aim of feasible industrial application, a facile in situ UV photo-grafting method is reported, which could ensure the formation of chemical bonds between fluoropolymer-grafted layer and substrate with a low cost commercial 2,2,2-trifluoroethyl methacrylate (TFEMA) as monomer. With low-density polyethylene (LDPE) film as a model substrate, four kinds of poly-TFEMA-grafted layer are fabricated on LDPE films with different surface morphologies: polymer brush, polymer network, crosslinked nanoparticles, and a micro- and nanoscale hierarchical structure. The experimental results showed that the water contact angles (CAs) of the LDPE films grafted with polymer brush, polymer network, and crosslinked nanoparticles were (103 ± 2)°, (95 ± 2)°, and (122 ± 2)°, respectively, which were much higher than that of LDPE film. The introduction of micro- and nanoscale hierarchical structures can dramatically improve the surface roughness, which will further enhance the film hydrophobicity, and the water CA can reach as high as (140 ± 1)°. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1059–1067
Co-reporter:Qian Liu;Lian-ying Liu;Yu-hong Ma 马育红
Chinese Journal of Polymer Science 2014 Volume 32( Issue 8) pp:986-995
Publication Date(Web):2014 August
DOI:10.1007/s10118-014-1469-y
In this paper, the effects of temperature from 60 °C to 80 °C and the molar ratios in monomer feed on the copolymerization of α-methylstyrene (AMS) and styrene (St) were studied. The resulting copolymers, designated as PAS, were characterized by FTIR, GPC, NMR and TGA. When the reaction temperature was below 75 °C, the molecular weights increased almost linearly as the evolution of the copolymerization. The phenomenon revealed that AMS could mediate the conventional free radical polymerization having some features of a controlled system. As the AMS/St = 50/50 (molar) in feed, the overall fraction of the AMS unit incorporated into the copolymer was as high as 42 mol%, the monomer conversion could be more than 90 wt% and the molecular weights could reach as high as 4400. However, since the styrene is more reactive than AMS, the AMS fraction in copolymer increased with the overall monomer conversion. The 13C-NMR revealed the products were random copolymers which had triads, such as -AMS-AMS-AMS-, -St-AMS-AMS-(-AMS-AMS-St-) and -St-AMS-St-. TGA curves demonstrated that the degradation temperature of the resulting copolymers went down from about 356.9 °C (0 mol% AMS) to 250.2 °C (42 mol% AMS). This behavior demonstrated that there exist weak bonds in the AMScontaining sequences which could be used as potential free radical generators.
Co-reporter:Haochuan Chen;Jiao Jiao;Changwen Zhao;Yuhong Ma;Wenchao Ma
Polymer Bulletin 2014 Volume 71( Issue 7) pp:1797-1811
Publication Date(Web):2014 July
DOI:10.1007/s00289-014-1155-9
Organotellurium compounds-mediated living radical polymerization (TERP) is one of the most robust tools of living free radical polymerizations (LRP). However, synthesis and purification of organotellurium compounds are time-consuming and to be operated in an inert atmosphere due to their extreme sensitivity to trace oxygen. In this article, a simple process of TERP, operating in open air, has been reported. It has demonstrated that the crude organotellurium compound, ethyl 2-phenyltellanyl-2-methylpropionate, could mediate 2,2′-azobis (isobutyronitrile) initiated styrene (St) and butyl acrylate (BA) polymerization as an LRP system. For the bulk and solution polymerization of St and the solution polymerization of BA, the molecular weights of produced polymers increased linearly with the monomer conversions. During the same time, the molecular weight distributions kept under 1.3. The UV–vis spectrum showed that the PS polymer chain bearing C-TePh end group. With the sequential monomer addition technique, a clean diblock polymer of PS-b-PBA was also obtained.
Co-reporter:XiaoHu Wei;Pathiraja A. Gunatillake;Graeme Moad;Ezio Rizzardo
Science China Chemistry 2014 Volume 57( Issue 7) pp:995-1001
Publication Date(Web):2014 July
DOI:10.1007/s11426-014-5128-5
Multi-functional mikto-arm star polymers containing three different arms [hydrophilic, SN-38-P(OEGMA8–9)11, cationizable, SN-38-P(DMAEMA)38 and hydrophobic, SN-38-P(BMA)26] were prepared by RAFT polymerization via an arm-first approach using a cleavable cross-linker. The star polymers were cleaved to the linear arms with tributylphosphine as a reducing agent. The decrease in molecular weight observed is consistent with the initial stars having approximately five arms. Blue fluorescence was observed when a solution of mikto-arm star was irradiated under a 365 nm light proving the retention of the SN-38 moiety during star formation by RAFT polymerization. Thus these polymer-drug conjugates can be considered as potential delivery vehicles for cancer therapy. The P(DMAEMA) arms can be quaternized using iodomethane, allowing star polymers to bind negatively charged small interfering RNA (siRNA) and potentially be used as a carrier for that material.
Co-reporter:Qian Liu;Lianying Liu;Yuhong Ma;Changwen Zhao
Journal of Polymer Science Part A: Polymer Chemistry 2014 Volume 52( Issue 22) pp:3283-3291
Publication Date(Web):
DOI:10.1002/pola.27390
ABSTRACT
A new visible light-induced controlled radical polymerization of methacrylate with perfluoro-1-iodohexane (CF3(CF2)5I) as the initiator in the presence of a photoredox catalyst (fac-[Ir(ppy)3]) was developed. Mechanistically, a photoexcited fac-[Ir(ppy)3]* complex reacted with dormant C-I species to generate the chain propagating radical and IrIVI complex, which could be reversibly reduced by the propagating radical. The molecular weight (Mn) and the corresponding distribution index (Mw/Mn = 1.4) were controlled in the polymerization of methyl methacrylate (MMA). For the polymerization of functional monomers, such as glycidyl methacrylate (GMA) and trifluoroethyl methacrylate, their monomer conversions could be up to 96 and 94%, respectively. No polymerization reaction took place without external light stimulation, indicating that the system was an ideal photo “on−off” switchable system. Furthermore, a clean diblock copolymer PMMA-b-PGMA was successfully synthesized with PMMA-I as the macroinitiator. With CF3(CF2)5I as the initiator, short CF3(CF2)5− group tags were introduced on the produced polymer chains. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3283–3291
Co-reporter:Xing Zhu, Yuhong Ma, Changwen Zhao, Zhifeng Lin, Lihua Zhang, Ruichao Chen, and Wantai Yang
Langmuir 2014 Volume 30(Issue 50) pp:15229-15237
Publication Date(Web):2017-2-22
DOI:10.1021/la5035273
Although the hydrogel network has been widely investigated as a carrier for enzyme immobilization, to in situ encapsulate enzymes into a hydrogel network in an efficient, practical, and active way is still one of the great challenges in the field of biochemical engineering. Here, we report a new protocol to address this issue by encapsulating enzyme into poly(ethylene glycol) (PEG) hydrogel network grafted on polymeric substrates. In our strategy, isopropyl thioxanthone semipinacol (ITXSP) dormant groups were first planted onto the surface of a plastic matrix with low density polyethylene (LDPE) film as a model by a UV-induced abstracting hydrogen-coupling reaction. As a proof of concept, lipase, which could catalyze esterification of glucose with palmitic acid, then was in situ net-immobilized into a PEG-based hydrogel network layer through a visible light-induced surface controlled/living graft cross-linking polymerization. This strategy demonstrates the following novel significant merits: (1) in comparison with the UV irradiation or high temperature, the visible light and room temperature used provide a friendly condition to maintain activity of enzyme during immobilization; (2) the uniqueness of controlled/living cross-linking polymerization not only makes it easy to form a uniform PEG hydrogel network, which is a benefit to avoid the leakage of net-immobilizing enzyme, but also to tune the net-thickness or capacity to accommodate enzyme; and (3) as compared to systems of nanoparticles and porous matrixes, the flexible/robust end-products of the surface net-immobilizing enzyme with polymer film are more suitable to be applied in a bioreactor due to their features of easier separation and reuse. We confirmed that this catalytic film could retain almost all of its initial activity after seven batches of 24 h esterifications. The proposed strategy provides an extremely simple, effective, and flexible method for enzyme immobilization.
Co-reporter:Tiao Yin;Hui Yun Sun;Jing Bo Zhao;Zhi Yuan Zhang;Wan Tai Yang
Polymer Engineering & Science 2014 Volume 54( Issue 4) pp:756-765
Publication Date(Web):
DOI:10.1002/pen.23612
This article provided a convenient method to synthesize aliphatic polyesteramides mainly composed of alternating diester diamide units by polycondensation and chain extension. Two kinds of polyesteramide prepolymers were prepared through melt polycondensation from N,N'-bis(2-hydroxyethyl)oxamide and adipic acid or sebacic acid. Chain extension of them was conducted with 2,2′-(1,4-phenylene)-bis(2-oxazoline) and adipoyl biscaprolactamate as combined chain extenders. The chain extended polyesteramides (ExtPEAs) were characterized by IR, 1H NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray scattering, tensile test, and dynamic thermomechanical analysis. The results showed that the ExtPEA(0, m)s were mainly constituted with the diester oxamide alternating units. They had Tm above 140.8°C and the initial decomposition temperature above 298.0°C. They crystallized in similar crystallites to Nylon-66 and were thermoplastic materials with tensile strength up to 31.47 MPa. POLYM. ENG. SCI., 54:756–765, 2014. © 2013 Society of Plastics Engineers
Co-reporter:Peng Yang and Wantai Yang
Chemical Reviews 2013 Volume 113(Issue 7) pp:5547
Publication Date(Web):April 24, 2013
DOI:10.1021/cr300246p
Co-reporter:Xiliang Cao, Tong Zhang, Jianyuan Deng, Lei Jiang, and Wantai Yang
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 3) pp:494
Publication Date(Web):January 11, 2013
DOI:10.1021/am302582x
This article reports on a new sequential strategy to fabricate monolayer functional organosilane films on inorganic substrate surfaces, and subsequently, to pattern them by two new photochemical reactions. (1) By using UV light (254 nm) plus dimethylformamide (DMF), a functional silane monolayer film could be fabricated quickly (within minutes) under ambient temperature. (2) The organic groups of the formed films became decomposed in a few minutes with UV irradiation coupled with a water solution of ammonium persulfate (APS). (3) When two photochemical reactions were sequentially combined, a high-quality patterned functional surface could be obtained thanks to the photomask.Keywords: APS; DMF; patterned surface; photochemical reaction; SAMs; UV;
Co-reporter:Xianhong Zhang, Haochuan Chen, Yuhong Ma, Changwen Zhao, Wantai Yang
Applied Surface Science 2013 Volume 277() pp:121-127
Publication Date(Web):15 July 2013
DOI:10.1016/j.apsusc.2013.03.178
Highlights
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Poly(1H,1H,2H,2H-perfluorooctyl methacrylate) brushes on BaTiO3 nanoparticles with enhanced dielectric performance.
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Surface initiated atom transfer radical grafting polymerization.
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Significantly improved dielectric constant and dielectric loss.
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Core–shell composite of fluoropolymer on BaTiO3.
Co-reporter:Yajiao Hao, Mengyu Chen, Jingbo Zhao, Zhiyuan Zhang, and Wantai Yang
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 19) pp:6410
Publication Date(Web):April 24, 2013
DOI:10.1021/ie302879t
One kind of nylon-610 oligomer (PrePA) was prepared from the reaction of nylon-610 salt with sebacic acid. Polyesteramide prepolymers (PrePEAs) having amide content from 10 to 60 mol % were synthesized through melt polycondensation from adipic acid, 1,4-butanediol, and the PrePA with the catalysis of stannous chloride. Chain extension of the PrePEAs was carried out at 210 °C using 2,2′-(1,4-phenylene)-bis(2-oxazoline) and adipoyl biscaprolactamate as combined chain extenders. The chain extended polyesteramides (ExtPEAs) with intrinsic viscosity up to 0.70 dL/g were synthesized. The ExtPEAs were characterized by FTIR and 1H NMR spectrum, differential scanning calorimetry, wide-angle X-ray scattering, thermogravimetric analysis, tensile test, and enzymatic degradation. The results showed that the ExtPEAs were biodegradable and had Tm from 95.20 to 155.67 °C, initial decomposition temperature over 325.3 °C, and tensile strength up to 33.1 MPa.
Co-reporter:Jian He, Dong Chen, Xu-Meng Fan, Li-Wei Wang, Jian-Yuan Deng, Wan-Tai Yang
Chinese Chemical Letters 2013 Volume 24(Issue 11) pp:970-974
Publication Date(Web):November 2013
DOI:10.1016/j.cclet.2013.07.026
Polymeric nanoparticles (NPs) have drawn great interest in the past few years due to their potential applications in the fields of biomedical and optical technologies. However, it is still a challenge to prepare functional polymeric NPs, especially for particle diameters smaller than 50 nm. In this work, we demonstrate a one-pot method to fabricate reactive poly(divinyl benzene-co-maleic anhydride) NPs (PDVBMAH NPs) through a self-stable precipitation polymerization process. The size and morphology of these PDVBMAH NPs were characterized in detail by scanning electronic microscopy, and their chemical structure was determined by IR. The results showed that these NPs were highly cross-linked and their diameter was about 30 nm with narrow distribution. Additionally, the DVB and MAH endow the NPs with reactive surface anhydride and pendant vinyl groups, and these particles could be further functionalized through reaction of these groups. A plausible pathway was proposed for the formation of PDVBMAH NPs.Reactive poly(divinyl benzene-co-maleic anhydride) nanoparticles were fabricated through a convenient method of self-stable precipitation polymerization. The morphology and other information about these polymeric nanoparticles were then characterized and investigated.
Co-reporter:Zhuo Li;Yuhong Ma
Journal of Applied Polymer Science 2013 Volume 129( Issue 6) pp:3170-3177
Publication Date(Web):
DOI:10.1002/app.39037
Abstract
A facile and environment friendly process, called water-solid phase suspension grafting polymerization, was developed to prepare polypropylene-g-poly(methyl methacrylate) (PP-g-PMMA) copolymer with a submicrometer microdomain. In this approach, graft polymerization was elaborately regulated to occur within micropores of polypropylene particles prepared by reactor granule technology. FTIR spectra of the samples after extraction demonstrated that PMMA was successfully grafted onto the PP. The results showed grafting percentage (GP) of PMMA increased with the increasing monomer ratios to PP and that could reach 13.6%. Whereas the grafting efficiency decreased as the monomer ratio increased. The addition of second monomer styrene improved GP up to 24.5%. Differential Scanning Calorimetry tests showed that the grafting of PMMA have a slight effect on the melting point and the relative crystallinity of PP. TEM micrographs demonstrated PMMA domains distributed in PP matrix with sizes ranging from about 100 to 300 nm. In addition, Shear viscosity increased with the growing GP indicated by rheological measurement. The preliminary evaluation showed PP-g-PMMA was effective in improving the compatibility of PP/acrylonitrile-styrene-acrylate blends. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Xianhong Zhang;Changwen Zhao;Yuhong Ma;Haochuan Chen
Macromolecular Chemistry and Physics 2013 Volume 214( Issue 22) pp:2624-2631
Publication Date(Web):
DOI:10.1002/macp.201300442
Co-reporter:C. Y. Li, F. J. Xu, and W. T. Yang
Langmuir 2013 Volume 29(Issue 5) pp:1541-1550
Publication Date(Web):December 21, 2012
DOI:10.1021/la302866n
The functionalization of polymer surfaces via surface-initiated atom transfer radical polymerization (ATRP) is of crucial importance to prepare various functional materials. It is generally complicated to conduct ATRP on different organic material surfaces. In this work, a facile photoinduced one-step method was first developed for the covalent immobilization of ATRP initiators on the C–H group-containing substrates such as biaxially oriented polypropylene (BOPP). The C–H bonds of precise location of inert polymer surfaces were readily transferred to bromoalkyl initiator, followed by ATRP of 2-(dimethylamino)ethyl methacrylate (DMAEMA) and glycidyl methacrylate (GMA), respectively, to produce the resultant patterned BOPP-g-P(DMAEMA) and BOPP-g-P(GMA) films. The epoxy groups of the P(GMA) microdomains can be aminated for covalently coupling IgG, while the P(DMAEMA) microdomains were used for immobilizing IgG via electronic interactions. The resultant IgG-coupled microdomains could interact with the corresponding target proteins, anti-IgG.
Co-reporter:Xiao-li Yao;Yu-hong Ma 马育红;Chang-wen Zhao
Chinese Journal of Polymer Science 2013 Volume 31( Issue 2) pp:333-345
Publication Date(Web):2013 February
DOI:10.1007/s10118-013-1224-9
The effects of the spin coating process parameters on the thickness of the SiOx layer of the BOPP/SiOx composite film were investigated. When the concentration of tetraethoxysilane (TEOS) increased from 12.5 vol% to 55% vol%, the SiOx thickness increased from about 80 nm to 470 nm. In the sol time range of 1.5 h to 5 h the SiOx layer thickness reached a maximum at about 4 h and the change of the thickness roughly matched the change of the silica colloidal sphere sizes in sol. When the spin-coating speed of the dispensing stage increased from 450 r/min to 500 r/min, the SiOx layer thickness drastically decreased from about 1.67 μm to 400 nm. While the spin-coating speed of the thinning and drying stage went up to 1200 r/min, the SiOx layer thickness was in the range of 330 nm to 390 nm. It was also found that the SiOx layer thickness was almost increased linearly from about 500 nm to 1.02 μm with the ratio of the commercial silica colloidal to the TEOS from 0.2 to 1.0. The water contact angles decreased to about 23.0° for the BOPP/Si-Sol composite film with 1.67 μm SiOx layer and about 4.0° for the BOPP/mixing Si-Sol composite film with 1.02 μm SiOx layer. Compared to BOPP, the light transparency of the BOPP/Si-Sol composite films decreased by about 5.5% with the SiOx layer from about 80 nm to 1.67 μm and by 7.0% for the BOPP/mixing Si-Sol composite film with the SiOx layer from about 350 nm to 1.02 μm respectively.
Co-reporter:Chunyan Li, Andrew Glidle, Xiaofei Yuan, Zhixiong Hu, Ellie Pulleine, Jon Cooper, Wantai Yang, and Huabing Yin
Biomacromolecules 2013 Volume 14(Issue 5) pp:
Publication Date(Web):March 18, 2013
DOI:10.1021/bm4000597
Creating patterns of biomolecules and cells has been applied widely in many fields associated with the life sciences, including diagnostics. In these applications it has become increasingly apparent that the spatiotemporal arrangement of biological molecules in vitro is important for the investigation of the cellular functions found in vivo. However, the cell patterning techniques often used are limited to creating 2D functional surfaces on glass and silicon. In addition, in general, these procedures are not easy to implement in conventional biological laboratories. Here, we show the formation of a living poly(ethylene glycol) (PEG) layer that can be patterned with visible light on plastic surfaces. This new and simple method can be expanded to pattern multiple types of biomolecule on either a previously formed PEG layer or a plastic substrate. Using common plastic wares (i.e., polyethylene films and polystyrene cell culture Petri-dishes), we demonstrate that these PEG-modified surfaces have a high resistance to protein adsorption and cell adhesion, while at the same time, being capable of undergoing further molecular grafting with bioactive motifs. With a photomask and a fluid delivery system, we illustrate a flexible way to immobilize biological functions with a high degree of 2D and 3D spatial control. We anticipate that our method can be easily implemented in a typical life science laboratory (without the need for specialized lithography equipment) offering the prospect of imparting desirable properties to plastic products, for example, the creation of functional microenvironments in biological studies or reducing biological adhesion to surfaces.
Co-reporter:Linyue Tong, Xin Cui, Wantai Yang and Jianping Deng
Journal of Materials Chemistry A 2012 vol. 22(Issue 14) pp:6697-6703
Publication Date(Web):23 Feb 2012
DOI:10.1039/C2JM15652K
This article reports on a novel type of polymeric microsphere consisting of poly(N-(1-phenylethyl)maleimide-co-styrene) (poly(N-PEMI-co-St)) and showing remarkable heat resistance. Such microspheres were prepared by dispersion polymerization with 2,2′-azobisisobutyronitrile as an initiator and poly(vinyl pyrrolidone) as a dispersant. The growth of the microspheres was observed with SEM. The effects of some crucial factors on the formation of the miscrospheres were investigated, including molecular weight and mass fraction of the dispersant, monomer concentration, and the initiator mass fraction. Microspheres with good morphology and narrow dispersion were prepared under the optimized conditions. TGA demonstrated the remarkably high thermal decomposition temperature (approx. 450 °C) of the poly(N-PEMI-co-St) microspheres.
Co-reporter:Jingyi Xie, Huan Wang, Huadong Bai, Peng Yang, Mengxue Shi, Peng Guo, Chen Wang, Wantai Yang, and Huaihe Song
ACS Applied Materials & Interfaces 2012 Volume 4(Issue 6) pp:2891
Publication Date(Web):May 3, 2012
DOI:10.1021/am201830t
Through combined application of wormlike-micelle and rod-coating technique, a general method was demonstrated for the facile reparation of thin transparent conductive films (TCF) of various nanomaterials and their hybrids on flexible plastics. The cetyltrimethylammonium hydroxide (CTAOH)/p-toluenesulfonic acid (CTAT) wormlike micelle system was selected for both the dispersion of different nanomaterials and the enhancement of viscosities of the coating fluids. With the single-walled carbon nanotubes (SWNTs)/wormlike micelle aqueous dispersions as coating fluid, TCFs of SWNTs on flexible poly(ethylene terephthalate) (PET) substrates made by rod-coating method were demonstrated. After doping by immersion into thionyl chloride solution, the sheet resistance of SWNTs thin films, which had a transmittance of about 78%, was as low as 480Ω/sq. This coating method was extended to the preparation of thin films or networks of other materials such as reduced graphene oxide and Ag nanowires. The obtained TCF from Ag nanowire networks has a low sheet resistance of 17Ω/sq, which is comparable to the value of best indium tin oxide (ITO) coating on plastic substrates. Finally, hybrid thin films of different nanomaterials were demonstrated by this method.Keywords: flexible; hybrid film; large-area conductive layer; road coating; transparent; wormlike micelle;
Co-reporter:Xuefeng Zheng, Miao Yue, Peng Yang, Qi Li and Wantai Yang
Polymer Chemistry 2012 vol. 3(Issue 8) pp:1982-1986
Publication Date(Web):28 May 2012
DOI:10.1039/C2PY20117H
The present article proposes a novel metal/odor/color-free strategy, called Cycloketyl Radical Mediated Living Polymerization (CMP). It is based on the use of the cyclo-compound 9,9′-bixanthene-9,9′-diol (BIXANDL), and proceeds similarly to Living Radical Polymerization (LRP) under mild thermal or photo stimuli. This technique shows significant potential for the practical large-scale production of industrial polymers.
Co-reporter:Dong Liu;Ling Zhang;Mingkun Li;Jianping Deng
Macromolecular Rapid Communications 2012 Volume 33( Issue 8) pp:672-677
Publication Date(Web):
DOI:10.1002/marc.201100776
Abstract
This communication reports the first integration of two significant concepts, “macromolecular helicity-derived chirality,” and “magneticity” in one single microsphere entity. The novel chiral magnetic composite microspheres consisted of magnetic Fe3O4 nanoparticles and optically active helical substituted polyacetylene. Therefore, they exhibited both remarkable optical activity and magneticity. The microspheres adsorbed (R)-(+)-1-phenylethylamine much more quickly than the other enantiomer, demonstrating the potential applications of the chiral magnetic composite microspheres in chiral recognition and chiral resolution.
Co-reporter:Yingying Huang;Yuanyuan Zhang;Jianping Deng
Macromolecular Rapid Communications 2012 Volume 33( Issue 3) pp:212-217
Publication Date(Web):
DOI:10.1002/marc.201100646
Abstract
This Communication reports two substituted polyacetylenes that can adopt helical structures of preferential screw sense in both emulsion (nanoparticle) and solution; however, the handedness of the macromolecular helices is just opposite in the two states. More interestingly, the helical screw sense of the polymers demonstrated a reversible transition between the two states. The unprecedented findings are of significant importance for acquiring new insights into helical polymers and for developing novel advanced chiral materials.
Co-reporter:Changwen Zhao, Xiaoli Yao, Yuhong Ma, Pengfei Yuan, Wantai Yang
Applied Surface Science 2012 Volume 261() pp:436-440
Publication Date(Web):15 November 2012
DOI:10.1016/j.apsusc.2012.08.028
Abstract
First a SiOx layer, as a barrier layer between a photo active anatase TiO2 layer and BOPP substrate, was coated on hydroxylated BOPP film by a sol–gel process. Then, TiO2 layer was formed on SiOx surface through liquid phase deposition. Thus a flexible BOPP/SiOx/TiO2 multilayer film which has photocatalytic activity was fabricated. The coating processes were monitored by FT-IR and UV–vis spectroscopy, scanning electron microscopy, atom force microscopy and water contact angle (CA) measurements. The thickness of SiOx and TiO2 layer was about 600 nm and 135 nm, respectively. Root mean square (RMS) roughness of the SiOx layer was about 2–3 nm while the surface of TiO2 layer was much coarse with RMS roughness about 30 nm which offered the large surface area. The TiO2 layer endowed multilayer film photoinduced hydrophilic conversion property evidenced by the fact that its surface water contact angle could reduce to about 5° after 1 h of UV irradiation. The photocatalytic degradation ability of multilayer film was evaluated using methyl orange as model contamination and the results indicating that the degradation is efficient.
Co-reporter:Xiaofang Yang, Lianying Liu, Wantai Yang
Polymer 2012 Volume 53(Issue 11) pp:2190-2196
Publication Date(Web):9 May 2012
DOI:10.1016/j.polymer.2012.03.038
By exploringly introducing a bicationic viologen, N-hexyl-N'-(4-vinylbenzyl)-4,4′-bipyridinium bromide chloride (HVV) to dispersion polymerization of styrene (St) in a mixture of methanol and water, we achieved the following results: (1) monodisperse, core-shell microspheres with antibacterial surface were prepared by a simple one-step procedure, (2) diameter, core radii and shell thickness of resultant particles could be controlled by concentrations of HVV, monomer and initiator, and composition of media, (3) HVV could act not only as a monomer as that in previous modifications, but also as an efficient, novel stabilizer, and its copolymerization with St at interfacial layer and coagglutination of (co-)oligomers on core surface due to its moderate reactivity and hydrophilicity were conceived to be main reasons for formation of core-shell structures. Effects of HVV on polymerization behavior of St, evolution of core-shell structure, and morphology, size of particles were investigated. Moreover, antibacterial activity of resulted microspheres against Staphylococcus aureus was assayed.
Co-reporter:Sheng-liu Wang;Xiao-fang Yang;Lian-ying Liu 刘莲英
Chinese Journal of Polymer Science 2012 Volume 30( Issue 6) pp:865-872
Publication Date(Web):2012 November
DOI:10.1007/s10118-012-1180-9
In order to achieve monodisperse particles with high content of antibacterial groups covalently bonded on surface, a bicationic viologen, N-hexyl-N′-(4-vinylbenzyl)-4,4′-bipyridinium bromide chloride (HVV) was devised as a surfmer in dispersion polymerization of styrene (St) using a mixture of methanol (or ethylene glycol) and water as media. Effects of content of HVV, its addition profile and composition of reaction media on particles size and incorporation of HVV moieties were mainly investigated. The attachment of silver and gold nanoparticles on particle surface under UV irradiation ascertained the surface-bonded HVV segments. SEM, TEM observations and XPS, zata potential measurements indicated that increase of initial HVV contents and addition of HVV (when polymerization had been performed for 3 h) led to grown particles and enhanced immobilization of HVV moieties. Using a mixture of ethylene glycol and water as reaction media, small particles (5202-142 nm) with highly attached HVV moieties were prepared. Furthermore, antibacterial efficacy of the resultant particles against S. aureus was assayed, and particles with more HVV moieties anchored on surface demonstrated greater efficiency of antibacterial activity.
Co-reporter:Jing Xu;Yu-hong Ma 马育红;Jing-yi Xie
Chinese Journal of Polymer Science 2012 Volume 30( Issue 2) pp:287-296
Publication Date(Web):2012 March
DOI:10.1007/s10118-012-1120-8
A one-step process to introduce both the aromatic and aliphatic primary amino groups with high chemoselectivity was developed. Triplet state acetone abstracts the hydrogen atoms from both the C-H bond of the polymeric film substrate and the O-H bond of phenol which is the building block and the amino group carrier. As a result, two kinds of free radicals, confined carbon-centered chain radicals of the polymer substrate and mobile oxygen-centered phenoxy radicals, were generated. Then the C-O bonds were formed by the coupling reaction between these two kinds of free radicals. p-Tyramine and p-aminophenol were used as amino carriers. The successful introduction of amino groups onto LDPE, BOPP and PET film substrates was demonstrated by measurements of water contract angle (CA), ultraviolet spectra (UV), X-ray photoelectron spectroscopy (XPS) and fluorescent microscopy. The processing factors, such as the UV-light intensity and irradiation time, concentrations of p-tyramine and p-aminophenol, and the ratio of acetone/water were investigated. The optimized process parameters are as follows: UV light intensity 9500 μW/cm2; irradiation time 18 min for BOPP and LDPE, 22 min for PET; the ratio of acetone/water = 1; and concentration of p-tyramine and p-aminophenol 15% for BOPP and LDPE, 1% for PET. Based on the UV absorbance, the amino groups on the polymeric substrates were estimated to be in the range of 6.3 × 10-6–9.5 × 10-6 mmol/mm2.
Co-reporter:Changwen Zhao;Zhengdong Zhang
Journal of Polymer Science Part A: Polymer Chemistry 2012 Volume 50( Issue 18) pp:3698-3702
Publication Date(Web):
DOI:10.1002/pola.26179
Co-reporter:Lei Ding;Chunni Chen;Jianping Deng
Polymer Bulletin 2012 Volume 69( Issue 9) pp:1023-1040
Publication Date(Web):2012 December
DOI:10.1007/s00289-012-0790-2
Optically active, thermosensitive, and amphiphilic polymer brushes, which consist of helical poly(N-propargylamide) main chains and thermosensitive poly(N-isopropylacrylamide) (PNIPAm) side chains, were prepared via a novel methodology combining catalytic polymerization, atom transfer radical polymerization (ATRP), and click chemistry. Helical poly(N-propargylamide) bearing α-bromoisobutyryl pendent groups was synthesized via catalytic polymerization, followed by substituting the –Br moieties with azido groups. Then, alkynyl terminated PNIPAm formed via ATRP was successfully grafted onto the azido functionalized helical polymer backbones via click chemistry, providing the expected polymer brushes. GPC, FT-IR, and 1H-NMR measurements indicated the successful synthesis of the novel amphiphilic polymer brushes. UV–vis and CD spectra evidently demonstrated the helical structures of the polymer backbones and the considerable optical activity of the final brushes. The polymer brushes self-assembled in aqueous solution forming core/shell structured nanoparticles, which were comprised of optically active cores (helical polyacetylenes) and thermosensitive shells (PNIPAm).
Co-reporter:C.Y. Li, W.C. Wang, F.J. Xu, L.Q. Zhang, W.T. Yang
Journal of Membrane Science 2011 Volume 367(1–2) pp:7-13
Publication Date(Web):1 February 2011
DOI:10.1016/j.memsci.2010.09.057
A facile method to immobilize the initiators onto the substrate is desirable for surface initiated atom transfer radical polymerization (ATRP). In this work, a two-step process was first developed for covalent immobilization of ATRP initiators on the outside and inside surfaces of the porous nylon membrane. The nylon membrane was functionalized with poly(dopamine), and the bromoalkyl initiators were then immobilized on the poly(dopamine) functionalized nylon membrane surfaces in a two-step solid-phase reaction, followed by ATRP of acrylic acid (AAc), which was deprotonated by the addition of NaOH in an aqueous solution. The resulting nylon membranes with grafted poly(acrylic acid) (PAAc) side chains were characterized by X-ray photoelectron spectroscopy (XPS). The morphology of the nylon membranes was studied by scanning electron microscopy (SEM). The results indicated that the grafted PAAc polymers formed uniformly inside the pores throughout the entire membrane. With the increase of the polymerizing time, the average diameter of the pores became smaller. A kinetics study revealed that the chain growth from the membranes was consistent with a “controlled” process. The nylon-g-PAAc membranes exhibit rapid and reversible responses of the flux to the environmental pH varied from 3 to 8. Between pH 3.5 and 5.5, the membranes demonstrated a pH-valve function as the carboxyl group changed from neutral to charged states with a corresponding variation of chain configuration.Graphical abstractResearch highlights▶ The bromoalkyl initiator was immobilized on the poly(dopamine) functionalized nylon membrane surface in a two-step solid-phase reaction. ▶ Acrylic acid (AAc), which was deprotonated by the addition of NaOH in a aqueous solution, was polymerized on the poly(dopamine) functionalized nylon membrane surface. ▶ The flux of aqueous solutions through the nylon-g-PAAc membranes exhibited a rapid and reversible response on the solution pH in the pH range of 3 to 8.
Co-reporter:Ci Song, Lei Li, Fangjie Wang, Jianping Deng and Wantai Yang
Polymer Chemistry 2011 vol. 2(Issue 12) pp:2825-2829
Publication Date(Web):21 Oct 2011
DOI:10.1039/C1PY00457C
An enantiomeric pair of novel chiral N-propargylthiourea monomers (monomers 1 and 2) and their racemate (monomer 3) were synthesized and polymerized in the presence of (nbd)Rh+B−(C6H5)4 as a catalyst. The resulting poly(1) and poly(2) could adopt stable helices and demonstrate optical activity in solvents of low polarity (e.g.CHCl3), according to circular dichroism and optical rotation measurements. But for poly(3), no considerable CD signal was observed at 320 nm and above. Poly(1) and poly(2) kept stable helical structures in a temperature range from 0–60 °C, while failed to maintain helix in polar solvents. Helical poly(1) and poly(2) exhibited strong complexing ability towards Fe(III) ions, based on which novel sensors may be developed next.
Co-reporter:Lei Ding, Yi Li, Jianping Deng and Wantai Yang
Polymer Chemistry 2011 vol. 2(Issue 3) pp:694-701
Publication Date(Web):11 Nov 2010
DOI:10.1039/C0PY00198H
We present a facile approach for the preparation of hydrophobic helical poly(N-propargylamide)s in aqueous medium instead of toxic and volatile organic solvent by using a monomer/cyclodextrin inclusion complex. Four hydrophobic substituted acetylene monomers were investigated in this study. Their inclusion complexes with hydroxypropyl-β-cyclodextrin (HP-β-CD) and hydroxypropyl-γ-cyclodextrin (HP-γ-CD) were prepared in water and identified with FT-IR and NMR spectroscopy. Polymerizations of the complexes were successfully carried out in aqueous solution in the presence of a water-soluble Rh-based catalyst [Rh(cod)2BF4; cod = 1,5-cyclooctadiene]. The as-prepared poly(N-propargylamide)s exhibited little difference in composition from the counterparts obtained in organic solvent according to FT-IR analysis. Circular dichroism and UV-Vis absorption spectra demonstrated that the as-prepared poly(N-propargylamide)s could take ordered helical conformations. The reusability of cyclodextrins in the polymerization was investigated quantitatively, which should be one of cyclodextrins' advantages but has never been highlighted before in literature. The versatile method for preparing hydrophobic helical poly(N-propargylamide)s can efficiently reduce the use of noxious organic solvents and can be applicable to the preparation of other helical polymers.
Co-reporter:Bo Chen;Ci Song;Xiaofeng Luo;Jianping Deng
Macromolecular Rapid Communications 2011 Volume 32( Issue 24) pp:1986-1992
Publication Date(Web):
DOI:10.1002/marc.201100557
Abstract
Cross-linked microspheres consisting of optically active helical substituted polyacetylenes are reported. For preparing the microspheres, substituted polyacetylene copolymers with pendent polymerizable CC bonds are first prepared and then used as macromonomers to copolymerize with acrylates via suspension polymerization, providing cross-linked microspheres. The helical polymer segments render the microspheres with optical activity, whereas the acrylate-based polymers afford the swelling property. CD and UV-vis spectra demonstrate the optical activity of the microspheres. The microspheres preferably adsorb (R)-(+)-1-phenylethylamine, (R)-(+)-N-benzyl-1-phenylethylamine, and Boc-D-alanine, whereas released Boc-L-alanine rather more rapidly than its enantiomer.
Co-reporter:Lei Ding, Yi Li, Di Jia, Jianping Deng, Wantai Yang
Carbohydrate Polymers 2011 Volume 83(Issue 4) pp:1990-1996
Publication Date(Web):1 February 2011
DOI:10.1016/j.carbpol.2010.11.005
This article reports the first oil-absorbents consisting of β-cyclodextrin (β-CD) and showing high oil absorbency. To prepare such oil-absorbents, a β-CD derivative (β-CD-A) was synthesized and then underwent copolymerizations with octadecyl acrylate (ODA) and butyl acrylate (BA) in the presence of AIBN as initiator, yielding a cross-linked oil-absorbent. Herein β-CD-A served simultaneously as a co-monomer, cross-linking agent, and pore-forming agent. The oil-absorbent containing CD moieties showed much higher oil absorbency (CCl4, 79.1 g; CHCl3, 72.8 g; xylene, 43.7 g; and toluene, 45.7 g/g oil-absorbent) when compared with that without CD (CCl4, 11.7 g; CHCl3, 13.6 g; xylene, 16.5 g; and toluene, 19.2 g/g oil-absorbent). The desorption and the reusability of the oil-absorbents were quantitatively investigated, demonstrating the absorbents can be used for at least six times. The present oil-absorbents are expected to find practical applications particularly in the recovery of spilled oils and the treatment of wastewater.
Co-reporter:Shurun Li
Polymers for Advanced Technologies 2011 Volume 22( Issue 10) pp:1442-1445
Publication Date(Web):
DOI:10.1002/pat.1623
In this paper, we report on the synthesis of poly(acrylamide) (PAM) hydrogels by photoinitiation with a thick system. The hydrogels exhibited gradient crosslinking density along the light path. Thermogravimetric analyses (TGA) proved the same effects. We investigated some factors affecting the swelling ratio of the hydrogels such as crosslinking agent concentration, photoinitiator concentration, and monomer concentration. The as-prepared hydrogels might have some potential applications in drug delivery systems and other function materials. Copyright © 2009 John Wiley & Sons, Ltd.
Co-reporter:Yuanyuan Zhang;Xiaofeng Luo;Jianping Deng
Macromolecular Chemistry and Physics 2011 Volume 212( Issue 4) pp:353-360
Publication Date(Web):
DOI:10.1002/macp.201000606
Co-reporter:Shan Jiang;Jianping Deng;Qiang Yu
Journal of Applied Polymer Science 2011 Volume 120( Issue 1) pp:466-473
Publication Date(Web):
DOI:10.1002/app.33186
Abstract
Copolymers obtained from radical copolymerization of α-methylstyrene (AMS) and glycidyl methacrylate (GMA) behave as macroinitiators, when heated in the presence of a second monomer, giving rise to block copolymers. The relevant degradation and initiation polymerization mechanism of the macroinitiators were studied. Thermal depropagation of the macroinitiators generated monomers, identified by 1H-NMR, photoionization mass spectroscopy and FT-IR. According to the results of structure analysis by GPC, ESR and NMR spectroscopy, the AMS-GMA (head-head) and AMS-AMS (head-head) bonds in the macroinitiators are easily scissored providing free radicals when the temperature is above 80°C. The radicals lead to subsequent polymerization of the second monomer, and thereby block copolymers are formed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Co-reporter:Lei Li, Xiaoying Du, Jianping Deng, Wantai Yang
Reactive and Functional Polymers 2011 71(9) pp: 972-979
Publication Date(Web):September 2011
DOI:10.1016/j.reactfunctpolym.2011.06.006
Co-reporter:Dong Liu, Yi Li, Jianping Deng, Wantai Yang
Reactive and Functional Polymers 2011 71(10) pp: 1040-1044
Publication Date(Web):1 October 2011
DOI:10.1016/j.reactfunctpolym.2011.07.009
This article reports a novel type of composite microspheres showing magnetic properties. The composite microspheres consist of Fe3O4, silica, and poly(γ-benzyl-l-glutamate) (PBLG). For preparing such composite microspheres, Fe3O4 nanoparticles were fabricated by the solvothermal method and then coated with a silica shell by tetraethoxysilane. Subsequently, amino groups were introduced on the above Fe3O4-silica spheres by using 3-aminopropyltriethoxysilane. Finally, the obtained spheres were used as initiator for polymerizing γ-benzyl-l-glutamate N-carboxyanhydride (BLG-NCA), providing the anticipated magnetic composite microspheres. Such microspheres were characterized by FT-IR, TEM, large-angle powder XRD, and vibrating sample magnetometer. FT-IR spectra demonstrated that the PBLG chains adopted α-helical conformations. The magnetic composite microspheres showed a high saturation magnetization of 34.1 emu/g and the expected rapid magnetic responsivity.
Co-reporter:Shiyue Liu, Chenguo Li, Jingbo Zhao, Zhiyuan Zhang, Wantai Yang
Polymer 2011 Volume 52(Issue 26) pp:6046-6055
Publication Date(Web):13 December 2011
DOI:10.1016/j.polymer.2011.10.048
A Nylon-6 oligomer (PrePA) was synthesized by ring-opening polymerization from ε-caprolactam with 2-amino-ethanol under the catalysis of H3PO3. Polyesteramide prepolymers (PrePEAs) having amide content from 10 to 60 mol% were prepared through melt polycondensation from adipic acid, 1,4-butanediol and the PrePA. Chain extension of PrePEAs was carried out at 200 °C using 2,2′-(1,4-phenylene)-bis(2-oxazoline) and carbonylbiscaprolactamate as combined chain extenders. The chain-extended polyesteramides (ExtPEAs) with intrinsic viscosity up to 0.61 dL/g were synthesized. The ExtPEAs were characterized by FT-IR and 1H NMR spectra, differential scanning calorimetry, wide angle X-ray scattering, thermogravimetric analysis and tensile test. The results showed that the ExtPEAs mainly crystallized in the Nylon-6 crystallites. ExtPEAs had Tg from −46.71 to 4.28 °C, Tm from 106.69 to 139.92 °C, thermal stability with initial decomposition temperature over 339 °C, tensile strength up to 30.89 MPa and stain at break higher than 797.1%. These ExtPEAs were strong, thermally stable and tough thermoplastic polymers.
Co-reporter:Yuhong Ma, Lianying Liu, Wantai Yang
Polymer 2011 Volume 52(Issue 19) pp:4159-4173
Publication Date(Web):1 September 2011
DOI:10.1016/j.polymer.2011.07.027
This feature article covers the fundamental chemistry and applications of photo-induced living surface grafting polymerization. The mechanism of activation of inert alkyl C–H bonds of polymer substrates, the structures of the active free radical and reversible dormant species, the modes of the grafting chain growth (including linear, branched and cross-linked variants), and the role of spatial effect are discussed. Two technologies, i.e., 1-step and 2-step processes, their features and applications in fabricating polymer brushes with precisely controlled patterns, desired functions, branched and block grafting chains on planar substrates, and polymer lamination are presented. The fabrication of 3-dimensional covalently bonded polymer particles, such as nano-sized polymer particle monolayers (with uniform and bimodal distributions), discrete solid and hollow polymer particles of micrometer size, and multilayer polymer particles on polymeric substrates are also introduced. In the last part, the application of photo-induced living surface grafting polymerization in non-planar surface modifications, such as the preparation of core–shell polymer particles, Janus particles and cross-linked hydrogels with hairy polymer chains is summarized.Figure optionsDownload full-size imageDownload as PowerPoint slide
Co-reporter:Dong Liu;Xiaoying Du;Yuanyuan Zhang;Jianping Deng
Macromolecular Research 2011 Volume 19( Issue 7) pp:729-733
Publication Date(Web):2011 July
DOI:10.1007/s13233-011-0712-4
Co-reporter:Jie Liang, Yuhong Ma, Feng Wang and Wantai Yang
Chemistry of Materials 2010 Volume 22(Issue 14) pp:4254
Publication Date(Web):June 18, 2010
DOI:10.1021/cm100940s
A novel chemical strategy for fabricating flexible, transparent, and conductive poly(3,4-ethylenedioxythiophene) (PEDOT) films with a nanofibrillar morphology by in situ deposition on commercial plastic substrates has been developed. The key points of the strategy include (1) preimplanting surface sulfate groups (SO4−) onto the substrate surface by a confined photocatalytic oxidation (CPO) technique, which was critical both for improving the adhesion of the PEDOT with the substrate via static interactions and for inducing polymerization of EDOT onto the substrate surface, and (2) deliberately controlling the nanofibrillar network morphology by means of the reaction recipe and parameters, which was critical for balancing conductivity and transparency. On the basis of this design, with BOPP as a model substrate, PEDOT−BOPP composite films approximately 20 nm in thickness with a transparency as high as 90% and a conductivity of 300 S/cm were obtained. Moreover, XPS data demonstrated that the SO4− implanted on the substrate surface constituted the primary dopant of the deposited PEDOT, and peeling tests with 3M Scotch adhesive tape proved that the adhesion between the substrate and PEDOT was drastically enhanced. Combined with a photomask, a PEDOT micropattern on the polymer substrate could also be fabricated.
Co-reporter:Kang Zhou, Linyue Tong, Jianping Deng and Wantai Yang
Journal of Materials Chemistry A 2010 vol. 20(Issue 4) pp:781-789
Publication Date(Web):30 Nov 2009
DOI:10.1039/B918132F
A novel class of hollow polymeric microspheres was prepared from optically active helical polymers. To prepare the hollow spheres, optically active helical N-propargylamide copolymers (OAHPs) containing specially designed CC groups in pendent groups, were first synthesized and subsequently used as a macromonomer. Polymeric particles based on maleic anhydride (MAH) and vinyl acetate were prepared and used as sacrificial templates for the subsequent preparation of core/shell spheres, which were accomplished by using the system consisting of MAH, divinyl benzene and OAHP macromonomers. After extracting the core in the prepared core/shell particles, hollow microspheres grafted with optically active helical polymer chains were successfully obtained. The hollow particles were characterized with FTIR, field-emission SEM and TEM measurements. The size and the shell thickness of these hollow spheres were readily controllable. Circular dichroism (CD) spectra were recorded on the hollow spheres dispersed in THF. The intense CD effects indicated that the hollow spheres possessed high optical activity, arising from the helical polymer chains. The preferential adsorption of (R)-(+)-1-phenylethylamine to the (S)-form by the obtained hollow spheres clearly attested to the chiral recognition ability of the novel spheres.
Co-reporter:Xiaofeng Luo, Lei Li, Jianping Deng, Tiantian Guo and Wantai Yang
Chemical Communications 2010 vol. 46(Issue 16) pp:2745-2747
Publication Date(Web):17 Mar 2010
DOI:10.1039/B926134F
Achiral substituted acetylene monomers undergo aqueous catalytic emulsion asymmetric polymerizations in chiral micelles consisting of SDS and amino acid, providing optically active helical polymer emulsions. The asymmetric polymerizations lead to one-handed helical polymers, which are the origin of the optical activity of polymer emulsions.
Co-reporter:Linyue Tong, Xiaoqing Liu, Jianping Deng and Wantai Yang
Polymer Chemistry 2010 vol. 1(Issue 10) pp:1633-1637
Publication Date(Web):27 Aug 2010
DOI:10.1039/C0PY00116C
Polymerization of M1, a chiral N-propargylamide monomer, was carried out with (nbd)Rh+B−(C6H5)4 as the catalyst in five solvents to explore the effect of solvents on polymerization. All the polymerizations occurred smoothly and provided polymers in high yield, however the number-average molecular weights of the polymers differ largely, which is attributed to the different solubility of the polymers in solvents. The helical structure and the optical activity of the polymer prepared in THF was examined by CD and UV-Vis spectroscopy measurements in the five solvents and in solvent mixtures consisting of CH2Cl2 (a relatively good solvent) and THF (a relatively not-so-good solvent) in varied ratios. The polymer could adopt helical conformations in all the solvents, but different CD intensities and UV-Vis absorptions were observed. In CH2Cl2, the polymer exhibited lower intensity in both CD effect and UV-Vis absorption, while they were higher when the polymer was examined in THF, demonstrating that solvophobic effects made large contribution for the polymer chains to adopt helical conformations.
Co-reporter:Xiaoying Du, Jinbao Liu, Jianping Deng and Wantai Yang
Polymer Chemistry 2010 vol. 1(Issue 7) pp:1030-1038
Publication Date(Web):11 May 2010
DOI:10.1039/C0PY00028K
Copolymerizations of two novel N-propargylamide monomers [HCCCH2NHCOR, in M1, R: CHCH2; in M2, R: CH2CH2CH2CHCH2] with the other two N-propargylamide monomers (M3: achiral monomer; M4: chiral monomer), which were synthesized previously, were carried out in varied monomer feed ratios in the presence of (nbd)Rh+B−(C6H5)4, with the aim to prepare optically active polymers simultaneously possessing helical polymer backbones and pendent polymerizable vinyl groups. Among the four homopolymers derived from M1–M4, polymer 1 and polymer 2 cannot dissolve completely in any of the usual solvents, while polymer 3 and polymer 4 are known to form stable helical conformations. The expected copolymers were obtained in high yields (≥95%) and exhibited good solubility in several organic solvents. The obtained copolymers were found to adopt stable helical structures under the investigated conditions. The as-prepared helical copolymers bearing vinyl groups were further employed as macromonomers to copolymerize with N-isopropylacrylamide (NIPAM) in chloroform at 55 °C using 2,2′-azobis(isobutyronitrile) as an initiator and N,N′-methylenebisacrylamide as a cross-linking agent. The copolymerizations took place smoothly, quantitatively providing hydrogels containing helical polymer chains preformed in the first copolymerization step. The helical structures remained in the hydrogels according to circular dichroism spectroscopy measurements. The hydrogels preferentially adsorbed D-tryptophan and (R)-(+)-1-phenylethylamine in the corresponding two enantiomer pairs, demonstrating the potential applications of the novel optically active hydrogels in the areas of chiral recognition and chiral resolution.
Co-reporter:F. J. Xu, Y. Zhu, F. S. Liu, J. Nie, J. Ma and W. T. Yang
Bioconjugate Chemistry 2010 Volume 21(Issue 3) pp:456
Publication Date(Web):February 23, 2010
DOI:10.1021/bc900337p
Hydroxypropyl cellulose (HPC) possesses a lower critical solution temperature (LCST) above 40 °C, while the poly(N-isopropylacrylamide) (P(NIPAAm)) exhibits a LCST of about 32 °C. Herein, comb-shaped copolymer conjugates of HPC backbones and low-molecular-weight P(NIPAAm) side chains (HPC-g-P(NIPAAm) or HPN) were prepared via atom transfer radical polymerization (ATRP) from the bromoisobutyryl-functionalized HPC biopolymers. By changing the composition ratio of HPC and P(NIPAAm), the LCSTs of HPNs can be adjusted to be lower than the body temperature. The MTT assay from the HEK293 cell line indicated that HPNs possess reduced cytotoxicity. Some of the hydroxyl groups of HPNs were used as cross-linking sites for the preparation of stable HPN hydrogels. In comparison with the HPC hydrogels, the cross-linked HPN hydrogels possess interconnected pore structures and higher swelling ratios. The in vitro release kinetics of fluorescein isothiocyanate-labeled dextran and BSA (or dextran-FITC and BSA-FITC) as model drugs from the hydrogels showed that the HPN hydrogels are suitable for long-term sustained release of macromolecular drugs at body temperature.
Co-reporter:Fen Zhang;Le Cao
Macromolecular Chemistry and Physics 2010 Volume 211( Issue 7) pp:744-751
Publication Date(Web):
DOI:10.1002/macp.200900573
Co-reporter:Mirza Nadeem Ahmad, Jing-yi XIE, Yu-hong MA, Wan-tai YANG
New Carbon Materials 2010 Volume 25(Issue 2) pp:134-140
Publication Date(Web):April 2010
DOI:10.1016/S1872-5805(09)60021-4
Co-reporter:LuLin Wang;YuHong Ma;MengJun Chen;Hui Yao;XiaoMan Zheng
Science China Chemistry 2010 Volume 53( Issue 8) pp:1695-1704
Publication Date(Web):2010 August
DOI:10.1007/s11426-010-3193-y
This article presents a simple, fast and low-cost method to fabricate a flexible UV light photomask. The designed micropatterns were directly printed onto transparent hybrid composite film of biaxially oriented polypropylene coated with silica oxide (BOPP-SiOx) by an inkjet printer. Compared to the conventional chrome-mask, it is of advantages such as suitable for non-planar substrates, scalable for large area production, and extreme low cost. Combined with the confined photo-catalytic oxidation (CPO) reaction, the printed flexible BOPP-SiOx photomask was successfully used to pattern the shape of wettability of organic polymer surfaces, and then polyaniline patterns were deposited on the modified substrates with strong adhesion. With the above photomasks, the polyacrylic acid graft chains were duplicated on the poly (ethylene terephthalate) (PET) and BOPP substrates by photografting polymerization. We grafted polyacrylic acid (PAA) on a non-planar plastic substrate with this soft and thin plastic photomask. Scanning electron microscopy (SEM) and optical microscopy were used to characterize the surface morphology and thickness of ink layers of the printed photomask. Optical microscopy was used to characterize the deposition polyaniline micropatterns. It was found that the desired patterns were precisely printed on the modified polymer films and were applied in modifying organic polymer substrates. The printed photomask could be exploited in the fields such as prototype microfluidics, micro-sensors, optical structures and any other kind of microstructures which does not require high durability and dimensional stability.
Co-reporter:Jianping Deng, Yong Yu, Shuo Dun and Wantai Yang
The Journal of Physical Chemistry B 2010 Volume 114(Issue 8) pp:2593-2601
Publication Date(Web):February 5, 2010
DOI:10.1021/jp909115p
A novel type of hollow polymeric particles was prepared according to a strategy consisting of three major steps: the synthesis of template particles (PMV) based on maleic anhydride/vinyl acetate; the formation of core/shell particles by using maleic anhydride/divinylbenzene as comonomers, AIBN as initiator, and PMV as templates; and the removal of the core by dissolving it with an organic solvent. This route gave rise to core/shell and hollow particles in high yields, and the as-prepared particles possessed obvious advantages. The size of the core and the thickness of the shell were controllable by adjusting the reaction conditions. The shells were of high rigidity and strength as a result of the high cross-linking degree. The surface anhydride groups offered a platform for various postfunctionalization reactions of the particles. The nanoscale pores in the shells enabled an encapsulation of target compounds. The as-prepared hollow particles could be applied as “nanoreactors”. To attest to this concept, Ag-encapsulated composite particles were further prepared via redox reactions between NaBH4 and AgNO3 inside the hollow particles. A mechanism for the formation of core/shell particles and pores in the shells is proposed.
Co-reporter:F. J. Xu, F. B. Su, S. B. Deng and W. T. Yang
Macromolecules 2010 Volume 43(Issue 5) pp:2630-2633
Publication Date(Web):February 4, 2010
DOI:10.1021/ma902080q
Novel stimuli-responsive polyelectrolyte, poly(N-benzyl-N′-(4-vinylbenzyl)-4,4′-bipyridium dichloride) or P(BpyClCl), brushes were prepared from the benzyl-chloride-immobilized SiO2 nanoparticles via surface-initiated atom transfer radical polymerization (ATRP). The dicationions (BV2+) of the P(BpyClCl) brushes can be reduced by UV irradiation to become radical monocations (BV+·), which can oxidize back to the original BV2+ state by exposure to air. The fast switching between dicationic and monocationic states of the P(BpyClCl) brushes on the SiO2 nanoparticles can be used as the physically controllable means for the reduction of metal ions (such as Au, Pt, and bimetallic Au/Pt ions) without the need for any added metal reduction agents.
Co-reporter:Bo Chen, Jianping Deng, Xiaoqing Liu and Wantai Yang
Macromolecules 2010 Volume 43(Issue 7) pp:3177-3182
Publication Date(Web):March 10, 2010
DOI:10.1021/ma902722c
This article reports on a novel methodology for preparing a new class of core/shell nanoparticles. The nanoparticles consist of a unique core (composed of an optically active helical-substituted polyacetylene) and a shell (composed of a vinyl polymer) and thus exhibit optical activities. Such nanoparticles were synthesized by combining aqueous catalytic microemulsion polymerization and free radical polymerization in one specific system. The shells could be further cross-linked for improving the properties of particles. The investigations are of high importance not only in polymer chemistry due to the combination of catalytic polymerization and free radical polymerization in one system but also in materials due to the integration of “chirality” and “nano” concepts in one single material.
Co-reporter:Shengjie Lv, Lianying Liu and Wantai Yang
Langmuir 2010 Volume 26(Issue 3) pp:2076-2082
Publication Date(Web):October 1, 2009
DOI:10.1021/la9025766
There exists a great number of publications concerning the synthesis of core−shell and/or hairy particles by means of controlled/living polymerization. Nevertheless, how to fabricate ultrafine nanosized hairy particles, especially polymeric soft hairy particles, remains a significant challenge. This paper presents a simple self-developed approach consisting of a two-step photoinduced polymerization of cross-linked polyacrylamide (CLPAM) soft hydrogel nanoparticles (5−10 nm in diameter) grafted with poly(N-isopropylacrylamide) (PNIPAm) chains. The architecture of such ultrafine soft water-swollen CLPAM@PNIPAm core/shell nanoparticles (20−35 nm in diameter) demonstrated very specific temperature sensitive behaviors. During heating a fast association process was observed at approximately 33−34 °C and the singular hairy particles with 34 nm diameters clustered into aggregates that were ∼120 nm in diameter. Raising the temperature further, however, led to a decrease in size to about 100 nm at 45 °C. This behavior was attributed to the formation of hydrophobic shell layers accompanying the shrinkage of PNIPAm chains with chain polar transformations. With the contraction pressure produced by further shrinkage of the hydrophobic shell layers, the soft fully swollen PAM cores expelled water and diminished in size. During the cooling process, these contracted cores that were trapped in the aggregates gave rise to an early dissociation. The hydrophilic hairy CLPAM@PNIPAm particles are believed to be potentially useful as carriers to specific target regions, e.g., cells for controlled drug delivery and other smart biomaterial applications.
Co-reporter:Lei Li, Yan Li, Xiaofeng Luo, Jianping Deng, Wantai Yang
Reactive and Functional Polymers 2010 70(12) pp: 938-943
Publication Date(Web):December 2010
DOI:10.1016/j.reactfunctpolym.2010.09.006
Co-reporter:Dongyue Zhang, Tianzhu Zhang, Jianping Deng, Wantai Yang
Reactive and Functional Polymers 2010 70(6) pp: 376-381
Publication Date(Web):1 June 2010
DOI:10.1016/j.reactfunctpolym.2010.03.002
Homo- and co-polymerizations of a chiral N-propargylamide (M1 containing 2,2-dimethyl-5-oxo-1,3-dioxolane group) and an achiral N-propargylamide (M2 containing adamantane group) were carried out in the presence of (nbd)Rh+B−(C6H5)4. All the (co)polymers synthesized were obtained in a yield ⩾80%. Poly(1) assumed helices of a predominant handedness and exhibited an optical activity, while poly(2) formed helices of an equal amount of right- and left-handed screws and showed no optical activity. The maximum wavelength and CD signal intensity of the copolymers with varied M1/M2 ratios demonstrated considerable composition dependence. This observation was explained by the synergic effects between the pendent groups during the formation of helical structures.
Co-reporter:Xiaofeng Luo, Jie Chang, Jianping Deng, Wantai Yang
Reactive and Functional Polymers 2010 70(2) pp: 116-121
Publication Date(Web):February 2010
DOI:10.1016/j.reactfunctpolym.2009.11.001
Co-reporter:Fen Zhang, Yuhong Ma, Lianying Liu and Wantai Yang
The Journal of Physical Chemistry B 2010 Volume 114(Issue 34) pp:10970-10978
Publication Date(Web):August 10, 2010
DOI:10.1021/jp102936n
This article presents observations of three polymerization modes of a self-developed cation-charge-stabilized styrene/water/methanol dispersion polymerization system: (1) a water/methanol (20/80) system, corresponding to a typical dispersion polymerization mode where the particle nucleation occurred in the solution phase and growth in the particle phase; (2) a pure CH3OH system, including a first nucleation in the solution phase with growth by absorption of the small particles and polymers formed in this phase, and a secondary nucleation with growth in the particle phase, when high molecular weight copolymers appeared in the solution phase; and (3) a water/methanol (5/95) system, similar to the conventional dispersion polymerization mode during the first 90 min, with subsequent epitaxial growth. Interestingly, the metastable state of the nucleation stage, including minuscule 6-nm particles, their aggregates, and the aggregating process, was first observed experimentally. By quantitatively following the relationship of the deposited molecular weight and the nucleation/growth process in the three systems, it was proposed that the molecular weight of the deposited polymer had to reach a specific high value before they could absorb or capture monomer to form smooth/spherical nuclei or particles.
Co-reporter:S. C. Tang, J. Y. Xie, Z. H. Huang, F. J. Xu and Wantai Yang
Langmuir 2010 Volume 26(Issue 12) pp:9905-9910
Publication Date(Web):May 20, 2010
DOI:10.1021/la100344f
We report a photolithographic process for micropatterning of two-component biomolecules on a transparent organic film via lateral functional polymer brushes of poly(sodium acrylate) (P(AA)) and poly(glycidyl methacrylate) (P(GMA)). The pattern of binary polymer brushes were prepared via consecutive UV-initiated grafting processes, under the assistance of the in situ formed poly (4,4′-bi[N-(4-vinylbenzyl) pyridinium]) (P(BVV)) photomask. The epoxy groups of the P(GMA) microdomains can be aminated for covalently coupling biotin, while the P(AA) microdomains were used for immobilizing immunoglobulin (IgG). The resulting biotin- and IgG-coupled microdomains interact specifically with their corresponding target proteins, avidin and anti-IgG, respectively.
Co-reporter:Shurun Li;Jianping Deng
Journal of Polymer Science Part A: Polymer Chemistry 2010 Volume 48( Issue 4) pp:936-942
Publication Date(Web):
DOI:10.1002/pola.23849
Abstract
The amphiphilic poly(AM-co-SA)-ITXH macrophotoinitiator was synthesized by precipitation photopolymerization under UV irradiation with isopropylthioxanthone (ITX) as free radical photoinitiator. A novel method has been developed to prepare amphiphilic core-shell polymer nanospheres via photopolymerization of methyl methacrylate (MMA) in aqueous media, with amphiphilic copolymer macrophotoinitiator poly(AM-co-SA)-ITXH. During polymerization, the amphiphilic macroradicals underwent in situ self-assembly to form polymeric micelles, which promoted the emulsion polymerization of the monomer. Thus, amphiphilic core-shell nanospheres ranging from 70 to 140 nm in diameter were produced in the absence of surfactant. The conversion of the monomer, number average molecular weights (Mn), and particle size were found to be highly dependent on the macrophotoinitiator and monomer concentration. The macrophotoinitiator and amphiphilic particles were characterized by FTIR, UV-vis, 1H NMR, TEM, DSC, and contact angle measurements. The results showed the particles had well-defined amphiphilic core-shell structure. This new method is scientifically and technologically significant because it provides a commercially viable route to a wide variety of novel amphiphilic core-shell nanospheres. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 936–942, 2010
Co-reporter:Jianping Deng, Lifu Wang, Lianying Liu, Wantai Yang
Progress in Polymer Science 2009 Volume 34(Issue 2) pp:156-193
Publication Date(Web):February 2009
DOI:10.1016/j.progpolymsci.2008.06.002
As one of the major techniques developed to achieve surface modification of polymeric materials, UV-induced surface graft polymerization has been widely applied as a simple, useful and versatile approach to improve the surface properties of polymers. This review surveys the recent advances in UV light induced surface graft polymerizations, predominantly focusing on: (1) various initiating methods, controlled/living grafting, self-initiated grafting (grafting without the addition of photoinitiators), graft polymerizations with monomer pairs able to form charge transfer (CT) complexes, grafting in liquid, vapor and bulk phase, and the substrates used for grafting; (2) the topography of grafted surface layers, including granular structure, crosslinked structure, and well-defined structure; and (3) the application of techniques to prepare functionalized polymer surfaces with designed performances, e.g., to obtain polymer materials suitable for biomedical applications, membranes or microfluidics.
Co-reporter:F. J. Xu, Y. Ping, J. Ma, G. P. Tang, W. T. Yang, J. Li, E. T. Kang and K. G. Neoh
Bioconjugate Chemistry 2009 Volume 20(Issue 8) pp:1449
Publication Date(Web):July 31, 2009
DOI:10.1021/bc900044h
Cationic polymers have been of interest and importance as nonviral gene delivery carriers. Herein, well-defined comb-shaped cationic copolymers (HPDs) composed of long biocompatible hydroxypropyl cellulose (or HPC) backbones and short poly((2-dimethyl amino)ethyl methacrylate) (or P(DMAEMA)) side chains were prepared as gene vectors via atom transfer radical polymerization (ATRP) from the bromoisobutyryl-terminated HPC biopolymers. The P(DMAEMA) side chains of HPDs can be further partially quaternized to produce the quaternary ammonium HPDs (QHPDs). HPDs and QHPDs were assessed in vitro for nonviral gene delivery. HPDs exhibit much lower cytotoxicity and better gene transfection yield than high-molecular-weight P(DMAEMA) homopolymers. QHPDs exhibit a stronger ability to complex pDNA, due to increased surface cationic charges. Thus, the approach to well-defined comb-shaped cationic copolymers provides a versatile means for tailoring the functional structure of nonviral gene vectors to meet the requirements of strong DNA-condensing ability and high transfection capability.
Co-reporter:Lei Ding;Xuefeng Jiao;Jianping Deng;Weiguo Zhao
Macromolecular Rapid Communications 2009 Volume 30( Issue 2) pp:120-125
Publication Date(Web):
DOI:10.1002/marc.200800601
Co-reporter:Fen Zhang, Yaowen Bai, Yuhong Ma, Wantai Yang
Journal of Colloid and Interface Science 2009 Volume 334(Issue 1) pp:13-21
Publication Date(Web):1 June 2009
DOI:10.1016/j.jcis.2009.02.040
A novel dispersion polymerization system, with a methanol/water (MeOH/H2O) mixture as reaction medium and a polymerizable dimethylaminomethacrylate methyl chloride (DMC) as stabilizer was developed. By monitoring the polymerization evolution and observing the morphological changes of the polystyrene (PS) particles by SEM, it was found that this system had the following unique features: (1) a much lower amount of DMC (0.025 mass% based on styrene as opposed to 5 mass% for a routine system) was required to prepare monodisperse and stable PS particles; (2) the rate of polymerization was fast and the conversion was very high; (3) the monodisperse particles with average diameters of approximately 200–1600 nm could be directly obtained. These features were explained by a synergistic interaction between water and the quarternary ammonium cations. Combined with XPS, ion-exchange/conductometric titration, FTIR and 1H NMR analysis, a plausible polymerization mechanism through which the particles were stabilized by the PS-PDMC copolymer formed in situ was proposed.A novel dispersion polymerization system, with a polymerizable dimethylaminomethacrylate methyl chloride as stabilizer was developed. Much lower amount of stabilizer (0.025 wt%) was required to prepare monodisperse, stable and cation-charged PS particles.
Co-reporter:Shengli Zou;Huadong Bai;Peng Yang
Macromolecular Chemistry and Physics 2009 Volume 210( Issue 18) pp:1519-1527
Publication Date(Web):
DOI:10.1002/macp.200900100
Co-reporter:Cheng Jue;Li Juan ;Yang Wantai
Journal of Applied Polymer Science 2009 Volume 114( Issue 4) pp:1976-1983
Publication Date(Web):
DOI:10.1002/app.30630
Abstract
A novel trifunctional epoxy resin (TMBPBTH-EPOXY) was synthesized in our laboratory, and its curing behavior and performance were studied by curing with 4,4′-diaminodiphenylmethane (DDM) with the mass ratio of 30 : 100 of TMBPBTH-EPOXY and DDM. The mixtures of TMBPBTH-EPOXY/DDM were cured at 100, 140, and 160°C, respectively. The curing state was kept for different time from 1 to 6 h. The transition reaction of epoxide group during curing process was monitored by Fourier transform infrared spectroscopy. It was found that curing reaction was both dependent on the curing temperature and curing time, and the curing temperature has more effect on the curing reaction than the curing time. The curing activation energy was investigated by differential scanning calorimetry to be 55.13 and 55.10 kJ/mol. The glass transition temperature of TMBPBTH-EPOXY/DDM system was 240.2°C. The thermal decomposition temperature at different temperatures and time were studied by thermogravimetric analyzer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Co-reporter:Xuefeng Hu, Jieyu Zhang, Wantai Yang
Polymer 2009 50(1) pp: 141-147
Publication Date(Web):
DOI:10.1016/j.polymer.2008.10.058
Co-reporter:F. J. Xu, L. Y. Liu, W. T. Yang, E. T. Kang and K. G. Neoh
Biomacromolecules 2009 Volume 10(Issue 6) pp:
Publication Date(Web):April 30, 2009
DOI:10.1021/bm900307c
Protein-resistant poly(poly(ethylene glycol)monomethacrylate)-graft-Si(100), or Si-g-P(PEGMA) hybrids, were prepared via surface-initiated atom transfer radical polymerization (ATRP) of the poly(ethylene glycol)monomethacrylate (PEGMA) macromonomer from the hydrogen-terminated Si(100) surface (Si−H surface). The resultant robust Si−C bonded P(PEGMA) brushes can be further functionalized by the immobilization of human immunoglobulin (IgG) protein via different strategies, namely, the direct use of the alkyl halide chain ends preserved throughout the ATRP process and the postmodification of the hydroxyl side chains with by 1,1′-carbonyldiimidazole (CDI) or succinic anhydride (SA). The CDI exhibited a higher efficiency in activating the hydroxyl groups for coupling proteins. The surface density of the immobilized protein above 2.5 μg/cm2 could be readily achieved. The distribution of active protein-docking sites on the Si−C bonded P(PEGMA) brushes can be also controlled by controlling the brush length. The resulting IgG-coupled Si-g-P(PEGMA) hybrid surface interacts only and specifically with the anti-IgG protein, while the dense P(PEGMA) brushes effectively prevent nonspecific protein binding and fouling. The simple concomitant incorporation of protein-resistant P(PEGMA) brushes and highly specific and active protein onto silicon surfaces via robust Si−C bonding should readily endow the silicon substrates with new and interesting properties for applications in silicon-based protein sensors or microarrays.
Co-reporter:Huadong Bai;Zhenhua Huang
Journal of Polymer Science Part A: Polymer Chemistry 2009 Volume 47( Issue 24) pp:6852-6862
Publication Date(Web):
DOI:10.1002/pola.23724
Abstract
A novel visible light-induced living surface grafting polymerization was developed by a strategy in which isopropyl thioxanthone (ITX) was first photoreduced under UV light and sequentially coupled onto the surface of polymeric substrates, and the produced isopropyl thioxanthone-semipinacol (ITXSP) “dormant” groups were subsequently reactivated under visible light to initiate a surface grafting polymerization. By using glycidyl methacrylate (GMA) and low-density polyethylene (LDPE) films as models, a “living” surface grafting polymerization initiated by ITXSP under visible light at room temperature was observed. Both the surface grafting chain length versus grafting conversion of monomer and the grafting polymerization rate versus monomer concentration demonstrated a linear dependence, which is in accord with the known characteristics of living polymerization. The livingness rendered it possible to accurately control the thickness of the grafted layer by simply altering the irradiation time. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Phys, 2009
Co-reporter:Qing Yan, Tongyang Zhao, Yaowen Bai, Fen Zhang and Wantai Yang
The Journal of Physical Chemistry B 2009 Volume 113(Issue 10) pp:3008-3014
Publication Date(Web):February 12, 2009
DOI:10.1021/jp808974x
This paper reports on two important results regarding the precipitation polymerization of poly(divinylbenzene) (PDVB) in acetic acid (HAc). (1) Acetic acid is a novel kind of solvent worthy of investigation because it is amphipathic and innoxious. Thus, two kinds of model solvents, methyl ethyl ketone (MEK) and n-heptane, were selected to investigate the solvent effect on the particle morphology of PDVB-55 during precipitation polymerization in acetic acid. Monodisperse PDVB-55 microspheres were obtained with an MEK content of 30 vol % and a DVB loading of 2 vol %. Odd-shaped particles were found to almost disappear when MEK was added. For MEK contents up to 90 vol %, space-filling macrogels consisting of small particles with diameters of around 10 nm were obtained. More homocoagulated particles were produced when n-heptane was added, for which concentrations up to 50 vol % gave rise to cauliflower-like particles. Thus, in the acetic acid system, microspheres, pumpkin-like particles, macrogels, and coagulum could be successfully obtained. (2) The preparation of nonpolar PDVB-55 particles could be more predictable. For the first time—based on the regulation of former studies—the regularity of the dispersive term (δd) on the particle morphology for a PDVB precipitation polymerization system was reported. The three-dimensional Hansen solubility parameters were utilized to perfect the regularity of the Hildebrand solubility parameter. Microspheres or particles were formed in the range of moderate δ values for both parameters, i.e., δ = 20.2−24.3 MPa1/2 or δ = 16 MPa1/2. What was even more important, δd was found to be around 15.4 MPa1/2, and δh should be below 13.5 MPa1/2. Cyclohexane, cyclohexanone, n-butyl acetate, and 1,4-dioxane were used to verify this regularity, and positive results were obtained. Stable, uniform, and well-separated PDVB-55 microspheres and particles were produced as a result of interaction forces between oligomers, polymers, and solvent.
Co-reporter:Lianying Liu, Mingwei Ren and Wantai Yang
Langmuir 2009 Volume 25(Issue 18) pp:11048-11053
Publication Date(Web):June 12, 2009
DOI:10.1021/la901364a
Polymeric Janus particles are obtained by UV-induced selective surface grafting polymerizations and coupling reactions, in virtue of the light-absorption of photoreactive materials such as the immobilized photoinitiator and spread photoinitiator solution on the surfaces exposed to UV light and the sheltering of densely arrayed immovable particles from light. Varying the monomers or macromolecules applied in photografting polymerization or coupling reaction, and choosing diverse polymeric particles of various size, bicolor and amphiphilic Janus particles could be successfully achieved. Observations by fluorescence microscope, scanning electron microscope ,and transmission electron microscope confirmed the asymmetrical morphology of the resultant Janus particles.
Co-reporter:Jianping Deng, Bo Chen, Xiaofeng Luo and Wantai Yang
Macromolecules 2009 Volume 42(Issue 4) pp:933-938
Publication Date(Web):January 26, 2009
DOI:10.1021/ma8026468
This article reports on the first catalytic microemulsion polymerizations of substituted acetylenes in aqueous medium, providing nanoscale particles exhibiting optical activities and consisting of helical polymers. Three types of substituted acetylenes—one achiral N-propargylamide, two chiral N-propargylsulfamides, and chiral N-propaygylurea—were polymerized in the presence of hydrophobic Rh-based catalyst and with SDS as emulsifier and DMF as coemulsifier. Such microemulsion polymerizations led to nanoscale particles (70−110 nm in diameter) of polymers adopting helical conformations. The particles derived from the chiral monomers showed large specific rotations and intense circular dichroism (CD) signals. The obtained polymer dispersions demonstrated high stability. The thus-prepared polymers after removing the emulsifier and coemulsifier showed much stronger CD signals, and the helices were found to have higher thermal stability when compared with the corresponding polymers synthesized via catalytic polymerizations in organic solvents. The microemulsion polymerizations enable the polymers to form predominantly one-handed helical structures. The possible mechanisms were proposed for the formation of optically active polymer particles, for the formation of predominantly one-handed helices, and for the increased thermal stability of the helices formed in the polymers.
Co-reporter:Shenghua Gan, Peng Yang and Wantai Yang
Biomacromolecules 2009 Volume 10(Issue 5) pp:
Publication Date(Web):March 24, 2009
DOI:10.1021/bm900011h
Surface modification through implanting functional groups has been demonstrated to be extremely important to biomedical applications. The usage of organic polymer phase is often required to achieve satisfactory results. However, organic surfaces usually have poor chemical reactivity toward other reactants and target biomolecules because these surfaces usually only consist of simple alkyl (C−H) and/or alkyl ether (ROR′) structures. For the first time, we here report the potential to perform silanization techniques on alkyl polymer surface, which provide a simple, fast, inexpensive, and general method to decorate versatile functional groups at the molecular level. As an example, high-density primary amines could be obtained on a model polymer, polypropylene substrate, through the reaction between amine-capped silane, 3-aminopropyltriethoxysilane (APTES) and hydroxylated polypropylene surface. A model protein, immunoglobulin (IgG), could be effectively immobilized on the surface after transforming amines to aldehydes by the aldehyde−amine condensation reaction between glutaraldehyde (GA) and amines. The routes we report here could directly make use of the benefits from well-developed silane chemistry, and hereby are capable of grafting any functionalities on inert alkyl surfaces via changing the terminal groups in silanes, which should instantly stimulate the development of many realms such as microarrays, immunoassays, biosensors, filtrations, and microseparation.
Co-reporter:Shan Jiang;Jianping Deng
Macromolecular Rapid Communications 2008 Volume 29( Issue 18) pp:1521-1526
Publication Date(Web):
DOI:10.1002/marc.200800321
Co-reporter:Zhigang Zhang, Jianping Deng, Jiewen Li and Wantai Yang
Polymer Journal 2008 40(5) pp:436-441
Publication Date(Web):March 12, 2008
DOI:10.1295/polymj.PJ2007208
The influence of solvent on the geometrical and secondary structure of poly(N-propargyl-(1R)-camphor-10-sulfamide) (poly(1)) was investigated. 1H NMR spectra of poly(1) measured in varied solvent and at varied temperature showed that solvent influenced the mobility of the polymer’s main chain. Poly(1) adopted stable helices or disordered states in different solvents. Poly(1) could take helical conformation in toluene. Further characterization showed that hydrogen bond could form between the neighboring sulfamide groups. In mixed solvent comprising toluene and methanol, poly(1) underwent aggregation rather than taking helix when the content of methanol exceeded 40 vol %. In another binary solvent comprising DMSO and chloroform, poly(1) changed gradually from helical to disordered conformation with increasing the content of DMSO.
Co-reporter:Shan Jiang, Jianping Deng and Wantai Yang
Polymer Journal 2008 40(6) pp:543-548
Publication Date(Web):April 16, 2008
DOI:10.1295/polymj.PJ2007192
A novel way to prepare block copolymers is presented. Copolymerizations of α-methylstyrene (AMS) and glycidyl methacrylate (GMA) were carried out. The resulting copolymers, designated as poly(AMS-co-GMA) (PAG), were characterized by Fourier transform infrared spectroscopy (FT/IR), gel permeation chromatography (GPC), 1H NMR and thermogravimetric analyses (TGA). Based on TGA, two main degradations with two inflection points were observed at 178.20 °C and 342.1 °C in PAG, while only one degradation with an inflection point at 305.7 °C on homopolymer of GMA (PGMA), indicating the depolymerization started with scission of weak bonds in PAG. When heated, the scission of those weak bonds gave birth to chain radicals, which could further initiate the polymerization of other monomers. On the basis of this finding, a series of block copolymers, PAG-block-PMMA (Mn=63100 g/mol, Mw/Mn=1.77) and PAG-block-PSt (Mn=44700 g/mol, Mw/Mn=1.63), were prepared by simply heating PAG in the presence of the second monomer. This simple method is expected to be applied to kinds of monomers, and it might be suitable even for industrial applications.
Co-reporter:Qin Wang, Lianying Liu and Wantai Yang
Polymer Journal 2008 40(3) pp:192-197
Publication Date(Web):January 10, 2008
DOI:10.1295/polymj.PJ2007114
The grafting polymerization of styrene on the surface of commercial available vulcanized acrylonitrile butadiene rubber (NBR) latex was initiated by the heat decomposing cleavage of dormant groups of semipinacol (SP) immobilized firstly under UV irradiation. Extremely high grafting efficiency in the range from about 90% to nearly 100% could be achieved. Certain factors affinitive to the grafting polymerization, such as the concentration of monomer, the UV irradiation time taking on the immobilization of SP groups, and concentration of NBR latex containing SP groups, were investigated. It was noted that there was the highest conversion when the weight ratio of NBR and St was 4:6; the grafting polymerization had a constant grafting efficiency that was almost not affected by polymerization time and the ratio of NBR-SP/St. Furthermore, the morphologies of the thermal compression molded composites of NBR/NBR-g-PSt were observed by TEM and the thermal properties as well as tensile behaviors were examined. Obviously rubber-plastic transition could be displayed with the increasing of grafting yield. When the grafting yield was controlled at about 50%, the strength of modified rubbers increased significantly without losing its elongation.
Co-reporter:Wenbin Zhong;Yongxin Wang;Yan Yan
Macromolecular Symposia 2008 Volume 261( Issue 1) pp:97-103
Publication Date(Web):
DOI:10.1002/masy.200850113
Abstract
Summary: A novel strategy was developed in order to prepare monolayered polyaniline (PANI) submicrospheres on polymer substrates. The strategy involved two main steps, i.e., photografting of acrylate acid (AA) onto the surface of a polypropylene (PP) film, and subsequent oxidative polymerization of aniline on the grafted surface. It was found that the PANI monolayered hollow submicrospheres were immobilized on the surface of the PP film when the molar ratio of AA to aniline was about 1:1.6. A possible formation mechanism of the hollow PANI submicrosphere iss discussed.
Co-reporter:Qing Yan, Yaowen Bai, Zhe Meng and Wantai Yang
The Journal of Physical Chemistry B 2008 Volume 112(Issue 23) pp:6914-6922
Publication Date(Web):May 20, 2008
DOI:10.1021/jp711324a
This paper reports two important results with cross-linked precipitation polymerization. (1) Acetonitrile, a substance harmful to human health, is the most commonly used solvent for the synthesis of cross-linked polymeric microspheres by precipitation polymerization. Here, the much safer acetic acid replaced acetonitrile as a solvent in the precipitation polymerization of monodisperse cross-linked poly(divinylbenzene) (PDVB-55) microspheres. Pumpkin-like particles and microspheres were obtained. XPS results displayed a significant amount of double bonds on the surface of the particles. The effect of monomer content, temperature, and initiator amount on the formed particles were studied. For a DVB loading below 1 vol % at 70 °C, monodisperse microspheres with smooth surfaces and narrow diameters were successfully obtained. With a DVB loading of 2 vol % and by observing the shapes of particles obtained with three different temperature(60, 70, and 80 °C), we found that more spherical particles were obtained at higher temperatures and pumpkin-like particles were obtained at lower temperatures. No significant differences in morphology or the coefficient of variation (CV) of the particles were obtained for different initiator loadings, whereas the particle diameters could be increased with increased initiator concentrations. (2) In order to obtain a better understanding of the formation mechanism of these particles, time-dependent experiments, for the first time, were conducted in a hydrophobic monomer system. By tracing the whole polymerization process, some important results were found. First, with the polymerization time at 70 °C, the particle diameters were found to increase from 800 nm to 3.0 µm, the CV displayed a decrease, and the amount of spheres and the spherical evenness of the particle surfaces improved. Second, by quantitatively calculating the particle number from the yields and diameters data, it is found that starting from 3.1% yield or two hours reaction time the total amount of particles in the system is almost a constant (about 9.6 × 108/L), which means that no homocoagulation occurred and no new particles were generated after nucleation, and there is a linear relation between cubic diameters and yields. These two results give us a distinct impression that particle growth almost comes from capturing of newly formed oligomers. Based on the above results, a scheme for the particle formation is proposed, which shows that that pumpkin-like particles are caused by a prolonged nucleation including the homocoagulation of primary nuclei. The growth of the particles includes two modes, an in situ surface polymerization of monomer and the adsorption of PDVB-55 oligomers. The differences between results in acetonitrile and in acetic acid (higher yields, smaller size, not spherical but pumpkin-like particles in acetic acid) were due to the lower solubilizability of acetic acid which is the so-called proton-containing solvent with the hydrogen bonding structure.
Co-reporter:Jianping Deng;Shujun Liang;Cairong Zhang
Macromolecular Rapid Communications 2007 Volume 28(Issue 22) pp:
Publication Date(Web):9 OCT 2007
DOI:10.1002/marc.200700539
A novel strategy to prepare reactively compatibilized polymer blends is reported. An oligomer that consists of AMS (α-methyl styrene) and GMA (glycidyl methacrylate) is initially synthesized. When this oligomer is melt blended with poly(propylene) (PP), the GMA units in the oligomer are successfully grafted onto the PP chain, which is proven by measuring the FT-IR spectrum of the blended PP. When the oligomer is added to a blend of PP/Ny66, an in-situ compatibilization occurs, which leads to an increase in torque values during blending, a decrease in crystallinity degree of Ny66, and is observed by SEM images of the resulting blends. The compatibilizing effects of the oligomer are also observed in PP/Ny6 and polyethylene/Ny6 blends. A relevant compatibilization mechanism is proposed.
Co-reporter:Jianmin Lu;Xingying Zhang;Suhe Zhao
Journal of Applied Polymer Science 2007 Volume 104(Issue 6) pp:3924-3930
Publication Date(Web):27 MAR 2007
DOI:10.1002/app.26215
On the basis of our earlier work, extensive experiments were conducted to further investigate the regulating means of vinyl content, molecular weight, molecular weight distribution, and their effects on overall performance of star-shaped medium vinyl butadiene rubber (S-MVBR), which was prepared by “core-first” method with novel multifunctional organolithium as initiator, tetrahydrofuran (THF) as structure regulator, and raffinate oil as solvent. The results showed that vinyl content and molecular weight for one arm were easily regulated from 30 to 55%, 6–10 ten thousand, respectively. The tensile strength and elongation at break increased with increasing vinyl content and the dynamic heating was the lowest at vinyl content of 43%. S-MVBR had a relatively wide and symmetrical monomodal distribution, which was in favorable of good processing properties. S-MVBR containing Sn atom, with arm number of 3.8, molecular weight for one arm of eight 10,000, vinyl content of 50%, and distribution of molecular weight of 1.54, had optimal overall properties. When compared with cis-BR and linear MVBR, S-MVBR had low rolling energy loss, high wet grip, good mechanical and processing properties. It was an ideal rubber for high performance tire tread. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3924–3930, 2007
Co-reporter:Jianping Deng;Bo Chen;Zhigang Zhang
Polymer International 2007 Volume 56(Issue 10) pp:
Publication Date(Web):20 JUN 2007
DOI:10.1002/pi.2267
An N-propargylamide monomer, CHCCH2NHCOC(CH3)2CH2CH3 (monomer 9), was polymerized in the presence of (nbd)Rh+B−(C6H5)4 (nbd represents norbornadiene) in CH2Cl2, CHCl3, tetrahydrofuran or dimethylformamide, to provide polymers with moderate number-average molecular weights (Mn = 8700–12 100 g mol−1) in high yields (≥92%). The resulting poly(N-propargylamide) (polymer 9) dissolves almost completely in CHCl3 (>95%). According to the UV-visible spectra, measured at various temperatures, polymer 9 forms relatively stable helices over a wide temperature range (35–65 °C). Moreover, it exhibits reversible conformational transitions from an ordered helix to a random coil. On copolymerization of monomer 9 with CHCCH2NHCO(CH2)3CH3 (monomer 4) or CHCCH2NHCO(CH2)7CH3 (monomer 8), the solubility of polymer 9 improves noticeably. All the copolymers form helices under the experimental conditions. From the viewpoint of monomers 4 and 8, copolymerization with monomer 9 is favorable in terms of the copolymers forming helices. These findings reveal that the helical content and thermodynamic stability of the helices formed in the copolymers are likely to be controlled by selecting a suitable comonomer and by adjusting the composition of the copolymer. Copyright © 2007 Society of Chemical Industry
Co-reporter:Jianping Deng;Jianmin Wang;Weiguo Zhao;Zhigang Zhang
Macromolecular Chemistry and Physics 2007 Volume 208(Issue 3) pp:316-323
Publication Date(Web):6 FEB 2007
DOI:10.1002/macp.200600346
This paper deals with synthesis and characterization of a novel poly(N-propargylamide) containing cinnamamide groups (poly(1)) in its side chains. Monomer 1, CHCCH2NHCOCHCH(C6H5), was synthesized and polymerized with a rhodium catalyst, (nbd)Rh+B−(C6H5)4 (nbd = 2,5-norbornadiene). Effects of some factors on polymerization of monomer 1 such as solvent, temperature, and the ratio of monomer/catalyst were investigated in detail; polymers with moderate number-average molecular weights () and low index of polydispersity () were obtained. To improve the polymers' solubility and to elucidate whether poly(1) could form helical conformation, another N-propargylamide monomer 2, CHCCH2NHCOCH(CH2CH3)2, was employed to accomplish copolymerization with monomer 1. Copolymerization with monomer 2 improved obviously the solubility of the (co)polymers; the copolymers with certain monomer ratios could form helices under the examined conditions according to the related UV-vis spectra.
Co-reporter:Weiguo Zhao;Jianmin Wang;Zhigang Zhang;Jianping Deng
Macromolecular Chemistry and Physics 2007 Volume 208(Issue 2) pp:218-223
Publication Date(Web):23 JAN 2007
DOI:10.1002/macp.200600458
Copolymerization reactions of two N-propargylamides [1: HCCCH2NHCO(CH2)5CH3, 2: (HCCCH2NHCOC(CH3)3] were carried out with different monomer feed ratios. Compared with the two corresponding homopolymers, the series of resulting copolymers poly(1-co-2) had a higher helix content. They also performed very differently in conformational transitions, either from random coil to helix or from helix to random coil, mainly depending on the composition of the copolymers. Synergic effects among the pendent groups played a significant role in the copolymer main chains adopting stable helices.
Co-reporter:Wenbin Zhong;Jianping Deng;Yongxin Wang
Journal of Applied Polymer Science 2007 Volume 103(Issue 4) pp:2442-2450
Publication Date(Web):22 NOV 2006
DOI:10.1002/app.25503
A novel method for preparing electrically conductive polypropylene-graft-polyacrylic acid/polyaniline (PP-g-PAA/PANI) composite films was developed. 1,4-Phenylenediamine (PDA) was introduced on the surface of PP-g-PAA film, and then, chemical oxidative polymerization of aniline on PP-g-PAA/PDA film was carried out to prepare PP-g-PAA/PANI electrically conductive composite films. After each step of reaction, the PP film surface was characterized by attenuated total reflectance Fourier transform infrared spectroscopy. Static water contact angles of the PP, PP-g-PAA, and PP-g-PAA/PANI films were measured, and the results revealed that graft reactions took place as expected. The morphology of the PP-g-PAA film and the PP-g-PAA/PANI composite film were observed by atomic force microscopy. The conductivity and the thickness of the PP-g-PAA/PANI composite films with 1.5 wt % PANI were around 0.21 S/cm and 0.4 μm, respectively. The PANI on the PP-g-PAA/PANI film was reactivated and chain growing occurred to further improve the molecular weight of PANI. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2442–2450, 2007
Co-reporter:Jue Cheng, Jing Chen, Wan Tai Yang
Chinese Chemical Letters 2007 Volume 18(Issue 4) pp:469-472
Publication Date(Web):April 2007
DOI:10.1016/j.cclet.2006.12.033
A novel multifunctional epoxy resin was synthesized by polyphenol and epichlorohydrin. The structure and molecular weight of the multifunctional epoxy were characterized by FTIR and ESI-MS. DSC and DMTA were used to investigate the thermal property of multifunctional epoxy cured by DDS. The thermal resistance of the synthesized multifunctional epoxy was much better than a standard diglycidyl ether of bisphenol-A epoxy.
Co-reporter:Jing Bo Zhao;Wan Tai Yang;Kai Yong Li
Journal of Applied Polymer Science 2007 Volume 106(Issue 1) pp:590-598
Publication Date(Web):26 JUN 2007
DOI:10.1002/app.26635
HO-terminated polybutylene adipate (HO-PBA-OH) with molecular weight from 1040 to 3540 and HO-terminated polybutylene succinate (HO-PBS-OH) with intrinsic viscosity of 0.37 dL/g were synthesized through melt condensation polymerization from adipic acid or succinic acid with excess of butanediol. Chain extension of HO-PBA-OH or HO-PBS-OH with adipoyl biscaprolactamate and terephthaloyl biscaprolactamate was carried out at 200–240°C under reduced pressure. At the optimal conditions, chain-extended PBA with Mn up to 50,700, and Mw up to 125,700 was synthesized, and the chain-extended PBS with intrinsic viscosity of 1.25 dL/g was obtained. Meanwhile, p-toluenesulfonic acid, SnCl4 and zinc acetylacetonate catalyzed chain-extending reaction of HO-PBA-OH and HO-PBS-OH was also studied. The chain-extended polyesters were characterized by IR spectra, 1H-NMR spectra, and differential scanning calorimetry (DSC). The chain extension proceeds through the elimination of caprolactam rings in the chain-extenders, the adipoyl groups or the terephthaloyl groups couple the hydroxyl-terminated polyesters together and make the molecular weight of PBA or PBS increased, whether the acid catalyst such as p-toluenesulfonic acid was present or not. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Co-reporter:Zhengdong Zhang;Lingbing Kong;Jianping Deng;Huiyue Luo
Journal of Applied Polymer Science 2007 Volume 103(Issue 1) pp:118-124
Publication Date(Web):23 OCT 2006
DOI:10.1002/app.24783
In this article, a batch liquid-phase process was reported, by which the photo-initiated grafting polymerization could be carried out on the dark surfaces that were not directly irradiated by UV light. In the reaction system, an aluminum foil was placed horizontally to reflect UV light back and form a dark area underneath where the grafting polymerization took place. The occurrence of the polymerization was demonstrated by gravitational analyses and XPS spectra. The factors affecting the grafting reaction have been studied and the results showed that increasing irradiation time, reaction temperature, and benzophenone concentration and decreasing distance (D) between the light area and the place where grafting reaction took place were beneficial to the grafting reaction. The highest grafting density was obtained at a acrylic acid concentration of 15 vol %. Moreover, some further investigations were also made. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 118–124, 2007
Co-reporter:Xingying Zhang;Jianmin Lu;Suhe Zhao
Journal of Applied Polymer Science 2007 Volume 104(Issue 6) pp:3917-3923
Publication Date(Web):27 MAR 2007
DOI:10.1002/app.26099
To achieve low rolling resistance, high wet grip, and favorable overall performance, star-shaped medium vinyl butadiene rubber (S-MVBR) was designed and prepared by “core-first” method, where novel multifunctional organolithium containing Sn atom as initiator, THF as structure regulator, and carbon–hydrogen compound as solvent. The results showed that coupling reaction between SnCl4 and dilithium is stoichiometrical, and this method has much higher efficiency than the “arm-first” method. When dilithium is composed of 4–10 repeating units, the average arm number of S-MVBR is conveniently controlled between 3 and 5 by initiator functionality, which can be easily regulated by the mole ratio of active lithium of dilithium short chain to Cl− in SnCl4. As Sn coupling decreases numbers of noncrosslinking free ends, S-MVBR has lower rolling resistance, dynamic heating and higher wet grip than linear MVBR. Meanwhile, mechanical properties and processing properties are improved. And the formation of multiarm structure has little effect on viscosity. S-MVBR with arm number of 3.8 has optimal overall performance. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3917–3923, 2007
Co-reporter:Yuan Sui;Jingbo Zhao;Shenghua Gan;Hongchi Zhao
Journal of Applied Polymer Science 2007 Volume 105(Issue 2) pp:877-884
Publication Date(Web):6 APR 2007
DOI:10.1002/app.24746
This article presents the ring-opening polymerization of ε-caprolactone (ε-CL) from PP film modified with an initiator layer composed of OSn(Oct) groups. This method consists of two steps: (1) Sn(Oct)2 exchanged with the hydroxyl groups on the surface of PP film, forming the OSn(Oct) groups bonded on the surface; (2) surface-initiated ring-opening polymerization of ε-CL with the OSn(Oct) groups. The initiator layer is characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR), contact angles, and X-ray photoelectron spectroscopy (XPS). The growth of PCL chains from the initiator layer through ring-opening polymerization is successfully achieved. ATR-FTIR, XPS, and scanning electron microscope (SEM) are also used to characterize the grafted film. XPS results reveal that the PCL chains cover the surface of PP film after 4 h. The SEM images reveal that the PCL chain clusters grow into regular spheroidal particles, which can be changed into other different morphology by treated with different solvents. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Co-reporter:Yibing Yu;Lifu Wang;Lianying Liu
Journal of Applied Polymer Science 2007 Volume 106(Issue 1) pp:621-629
Publication Date(Web):26 JUN 2007
DOI:10.1002/app.26610
A surface photografting polymerization (λ > 300 nm) of a multifunctional monomer which was trimethylolpropane triacrylate (TMPTA), was conducted with benzophenone (BP) as photoinitiator and LDPE as model substrate, in mixed solvents containing tetrahydrofuran (THF) and water. Proved by ATR-IR, highly crosslinked grafted layer was generated rapidly under UV irradiation. Effects on percent conversion of grafting are detailed with, such as feed ratio of BP to TMPTA, mass percent of TMPTA in the reaction system, mass percent of water in the mixed solvents and addition of the second monomer, methyl methacrylate (MMA). As both verified by SEM and AFM, relatively planar grafted layer was produced when photografting was carried out merely in THF; adding water in the reaction system caused the formation of “craters” in the grafted layer. In addition, effects of mass percent of water in the mixed solvents, UV irradiation time, TMPTA concentration and addition of MMA on the size, shape and quantity of the “craters” were investigated by SEM. A plausible mechanism for the formation of “craters” is also proposed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Co-reporter:Zhigang Zhang;Jianping Deng;Weiguo Zhao;Jianmin Wang
Journal of Polymer Science Part A: Polymer Chemistry 2007 Volume 45(Issue 3) pp:500-508
Publication Date(Web):15 DEC 2006
DOI:10.1002/pola.21869
A novel chiral N-propargylsulfamide monomer (1a) and its enantiomer (1b) were synthesized and polymerized with (nbd)Rh+B−(C6H5)4 as a catalyst providing poly(1) (poly(1a) and poly(1b)) in high yields (≥99%). Poly(1) could take stable helices in less polar solvents (chloroform and THF), demonstrated by strong circular dichroism signals and UV–vis absorption peaks at about 415 nm and the large specific rotations; but in more polar solvents including DMF and DMSO, poly(1) failed to form helix. Quantitative evaluation with anisotropy factor showed that the helical screw sense had a relatively high thermal stability. These results together with the IR spectra measured in solvents showed that hydrogen bonding between the neighboring sulfamide groups is one of the main driving forces for poly(1) to adopt stable helices. In addition, copolymerization of monomer 1a and monomer 2 was conducted, the solubility of poly(1) was improved drastically. However, the copolymerization had adverse effects on the formation of stable helices in the copolymers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 500–508, 2007
Co-reporter:Jingyi Xie;Peng Yang;Li Zhang;Jing Yuan;Weina Liu
Journal of Polymer Science Part A: Polymer Chemistry 2007 Volume 45(Issue 5) pp:745-755
Publication Date(Web):5 JAN 2007
DOI:10.1002/pola.21822
A grafting technique was proposed for the preparation of polymer monolayer on polymeric substrate. On the basis of our recent work on polymer-supported inhibitor (PSI), hydroquinone (HQ) was first implanted onto polypropylene (PP) surface through UV-initiated grafting. The resulting immobilized HQ was used as PSI for the thermal-induced free radical polymerization (FRP) of acrylic acid (AA). The inhibition mechanism was similar to that of free HQ molecule, that is, polymer chain-carrying radical or peroxy radical could be deactivated by abstracting hydrogen atom from hydroxyl group of immobilized HQ, and the resulting oxyradical (semiquinone radical) combined with another active chain free radical. According to this mechanism, a devised redox initiator consisting of sodium hydrogen sulfite and ammonium persulfate was used to initiate FRP of AA in water at low temperature (50 °C). High crystalline biaxial oriented PP film with HQ immobilized was deliberately laid in this system as a radical trap to capture poly(acrylic acid) (PAA) short chain radical. Through X-ray photoelectron spectra (XPS) analysis it was found that the atom ratio of CHQ (carbon in HQ) to CCOOH (carbon in COOH) decreased with prolonging polymerization time and became stable after about 30 min. The formed PAA short chain on the surface showed a distribution of monolayer, and the saturated thickness was calculated as 5–7 Å. The degree of polymerization of graft chain in PAA monolayer was estimated as 15–20 through three different models. Relating to surface coverage being 100% in ideal densely packed PAA monolayer, real monolayer surface coverage in such reaction system was estimated as 12.3–18.5%. This method was expected to give us a general approach for constructing kinds of graft polymer monolayer on polymeric substrate, because the involved chemistry was only common inhibition reaction between immobilized inhibitor (HQ) and FRP system in solution (herein redox initiating system of AA). We named this grafting chemistry as confined surface inhibition reaction. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 745–755, 2007
Co-reporter:Peng Yang;Jingyi Xie
Macromolecular Rapid Communications 2006 Volume 27(Issue 6) pp:418-423
Publication Date(Web):6 MAR 2006
DOI:10.1002/marc.200500759
Summary: Under UV irradiation plus a photomask, a hydrophilic/hydrophobic hybrid polymer surface is created by sandwiching an ammonium persulfate solution between two polymer films. It is demonstrated that an effective conductive PANI micropattern can be fabricated on such a wettability patterned surface. For PET, a stable negative micropattern could be formed directly by the selective deposition of PANI onto the hydrophobic region. Alternatively, for PP or PI, direct deposition of PANI is non-selective, however, the PANI layer remains preferentially on the hydrophilic region by peeling off the PANI layer on the hydrophobic region to form a positive micropattern.
Co-reporter:Yongxin Wang;Zhaobin Qiu
Macromolecular Rapid Communications 2006 Volume 27(Issue 4) pp:284-288
Publication Date(Web):8 FEB 2006
DOI:10.1002/marc.200500765
Summary: A novel method, situ polymerization stringed assembly (SPSA), is proposed to prepare stable solid or hollow supramolecular polymer particles, which are assembled by numerous nanoparticles. By this method, the fabrication of primary nanoparticles (poly(methyl methacrylate), PMMA), the linkers (polyvinylpyrrolidone, PVP, chains) between the nanoparticles, and the final assembled solid or hollow particles could be achieved in just one-pot by methyl methacrylate (MMA)/N-vinylpyrrolidone (NVP) microemulsion polymerization under UV irradiation. The structures of the supramolecular particles can be changed from solid to hollow by tuning the mass ratio of MMA/NVP in the microemulsion. AFM, TEM, and SEM experiments are performed to identify the results.
Co-reporter:Yang Wantai;Deng Jianping
Journal of Applied Polymer Science 2006 Volume 99(Issue 5) pp:2710-2720
Publication Date(Web):19 DEC 2005
DOI:10.1002/app.21878
In view of the complexity of surface photografting polymerization of vinyl acetate/maleic anhydride (VAC/MAH) binary monomer systems, a novel method was adopted in the present article to obtain insight into the relevant grafting copolymerization mechanism. This method includes two steps: semibenzopinacol dormant groups were first introduced onto LDPE film by UV-irradiation and then thermally reactivated to produce LDPE macromolecular free radicals, which initiated the grafting copolymerization of VAC and MAH. It was demonstrated that, in the first step, the solvent used to introduce benzophenone (BP) to LDPE film largely affected the subsequent grafting copolymerization, which was closely related to the affinity of the solvent toward the substrate. The monomer feed composition had considerable influence on both the grafting and nongrafting copolymerization; however, the maximum copolymerization rates did not appear in the polymerization system with [VAC]/[MAH] being 1 : 1, but, in the system with a bit more VAC than MAH, as the total monomer concentration was raised, the maximum copolymerization rates tended to appear in the system with [VAC] equal to [MAH]. The relationship between the total copolymerization rate (RP) and monomer concentration was determined to be LnRP ∝ [VAC + MAH]1.83. All of these results indicated that both charge transfer (CT) complex formed by VAC and MAH and free monomers took part in grafting copolymerization. This feature differentiated the surface grafting copolymerization of VAC/MAH from the well-studied thermally induced alternating copolymerization of VAC/MAH. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006
Co-reporter:Deng Jianping;Liu Lianying;Yang Wantai
Journal of Applied Polymer Science 2006 Volume 99(Issue 5) pp:2810-2814
Publication Date(Web):21 DEC 2005
DOI:10.1002/app.22900
In the present article, a practically applicable method was developed, by which the compositions of the grafted chains achieved by UV-irradiated photografting polymerization of vinyl acetate–maleic anhydride (VAC-MAH)/low density polyethylene (LDPE) film systems can be determined. By measuring FTIR spectra of the films containing known amounts of VAC and MAH, standard working plots of the relationship between the ratio of the absorption peak area of MAH to that of VAC and the ratio of the content of MAH to that of VAC were set up. If the characteristic absorption peak areas of MAH and VAC on the grafted film are calculated, then according to the standard working plots, the ratio of MAH content to VAC content can be determined. It is proved that this method was effective in a wide range of MAH/VAC. Using this method, LDPE films containing different contents of MAH and VAC were characterized. The results show that the MAH content in the grafted film went up progressively, as the content of MAH in the monomer feed was raised; this phenomenon became more obvious when the total monomer concentration was increased, and the polymerization temperature was enhanced. These results should be attributed to the unique ability of MAH to abstract hydrogen when irradiated with UV light. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006
Co-reporter:Shoumei Cheng;Jianping Deng;Jianwu Zhu
Macromolecular Chemistry and Physics 2006 Volume 207(Issue 1) pp:75-80
Publication Date(Web):19 DEC 2005
DOI:10.1002/macp.200500401
Summary: A facile and effective surface grafting polymerisation method was designed and investigated to graft acrylonitrile (AN) onto low-density polyethylene (LDPE) film using benzoyl peroxide (BPO) as an initiator. This method consisted of two steps. In the first step, BPO was adsorbed on the surface of LDPE film by immersing LDPE film in BPO solution; in the second step, grafting polymerisation of AN onto LDPE film was carried out under heat. Because the grafting polymerisation was carried out with AN in vapour phase and the concentration of AN was very low, the homopolymerisation of AN could be effectively suppressed and therefore the grafting efficiency was very high (approaching 100%). Grafting percent (Gp) could be controlled from 0 to 118% by adjusting reaction conditions in the first step and/or in the second step respectively. A possible model was proposed to interpret the experimental results.
Co-reporter:Chang-Min Xing;Yong Yu;Wan-Tai Yang
Macromolecular Chemistry and Physics 2006 Volume 207(Issue 6) pp:621-626
Publication Date(Web):13 MAR 2006
DOI:10.1002/macp.200500527
Summary: The polymerization features of the novel stabilizer-free dispersion copolymerization of MAn and VAc were studied. It was found that the dispersion copolymerization of MAn/VAc is a fairly rapid process, which starts from a slow solution polymerization (below 10% conversion, Stage I) and follows a drastic increase of polymerization rate (10–80% conversion, Stage II) due to the known gel effect. Such process was accompanied by the increase of molecular weight of the copolymer formed ( from 1.2 × 104 to 3.8 × 104 g · mol−1) and the broadening of the molecular weight distribution ( from 2.4 to 8.0). Ea of Stage I was determined to be 76.7 kJ · mol−1, while the value of Stage II was 64.7 kJ · mol−1. The lower Ea in Stage II than that in Stage I suggests that there exists a shift of polymerization locus from the solution phase to the particle phase. Moreover, we found that the initial rate of polymerization increased with monomer concentration as well as initiator concentration, following the relationship (Rp)i ∝ [MAn + VAc] · [BPO]. This further implies that the dispersion copolymerization mainly proceeds as a solution polymerization in the very early stage.
Co-reporter:Lingbing Kong;Jianping Deng
Macromolecular Chemistry and Physics 2006 Volume 207(Issue 24) pp:2311-2320
Publication Date(Web):6 DEC 2006
DOI:10.1002/macp.200600299
Summary: A new reaction system was designed in order to allow the reaction between benzophenone (BP) and poly(vinyl acetate) chain/radical or monomer to progress under UV irradiation with relatively constant intensity of absorbed light. After the reaction, most BP-related products were successfully separated and were directly and particularly studied for the first time by a 600 MHz solution-state NMR spectrometer. 13C, 1H, DEPT-135, and 2D 1H-13C HSQC, 1H-13C HMBC NMR spectra were utilized for the analyses. In the mixed products, two new structures with new ether groups were detected and confirmed, besides detailed confirmation of benzopinacol and semi-benzopinacol-connected poly(vinyl acetate).
Co-reporter:Zhengdong Zhang;Lingbing Kong;Jianping Deng;Peng Yang
Journal of Applied Polymer Science 2006 Volume 101(Issue 4) pp:2269-2276
Publication Date(Web):27 MAY 2006
DOI:10.1002/app.23663
Surfaces unable-to-be-irradiated are those that could not be directly exposed to UV irradiation because of their irregular structure or instability under UV irradiation. It is difficult to conduct surface photografting on these kinds of surfaces with conventional photografting methods. Here, a novel one-step surface photografting method is introduced, by which some monomers were smoothly grafted on the surface of polymer substrates located in a region out of the reach of UV radiation. The mechanism is that the photochemical reaction is separated into three events, absorbing UV light in one place, then transporting light energy to another place, and reacting there; in other words, the conventional photochemical reaction is separated by space and time, and the key point is that the substrate does not need to be exposed to UV irradiation. The occurrence of grafting polymerization was proved by UV–vis, ATR-IR, SEM, XPS, and water contact angle measurements. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2269–2276, 2006
Co-reporter:P. Yang;X. X. Zhang;B. Yang;H. C. Zhao;J. C. Chen;W. T. Yang
Advanced Functional Materials 2005 Volume 15(Issue 9) pp:
Publication Date(Web):29 AUG 2005
DOI:10.1002/adfm.200400335
Introducing amine functional groups on polymer surfaces is extremely important for studying various processes that involve polymer surfaces. We report a novel and extremely simple method for preparing a tertiary-amine-terminated poly(ethylene terephthalate) (PET) surface by using a UV-light-induced surface aminolysis reaction. X-ray photoelectron spectroscopy and attenuated total-reflection infrared spectroscopy give direct evidence of the incorporation of tertiary amine functionalities and the possible reaction mechanism behind this technique. Tertiary amines are easily protonated, so we have developed an extremely simple method for immobilizing and patterning biomolecules on a soft surface by the electrostatic self-assembly of proteins, such as immunoglobulin (IgG) and horseradish peroxide (HRP), onto a patterned, aminated surface. An enzyme–substrate reaction, which is followed optically by observing the resulting precipitation on the surface, is used to reveal the patterned immobilization of HRP, where 3-amino-9-ethylcarbazole, as a substrate for HRP, is deposited on the aminated surface after HRP adsorption. Fluorescein isothiocyanate-labeled IgG (FITC-IgG) has been immobilized electrostatically onto the ordered aminated spots, and the fluorescence intensity ratio of the IgG-immobilized region (inside the spot) to the background (outside the spot) is about 5:1, as calculated from a fluorescence image and fluorescence spectra obtained by microlaser confocal Raman spectroscopy. We have found that the background intensity is mainly caused by the autofluorescence of virgin PET, and after subtracting this value from the measured intensity inside and outside the spot, respectively, a much higher intensity ratio between the spot and the background is obtained (about 22:1). The patterned immobilization of FITC-IgG has been further proven by examining the change in intensity inside the spot after photobleaching the fluorophore.
Co-reporter:Biao Yang, Wantai Yang
Journal of Membrane Science 2005 Volume 258(1–2) pp:133-139
Publication Date(Web):1 August 2005
DOI:10.1016/j.memsci.2005.03.013
A pH-switching membrane with novel pore-covering structure was designed and synthesized by photografting 4-vinylpyridine (4VP) onto the poly(ethylene terephthalate) (PET) track membranes. The membrane has a thin grafting layer, which was confined to the membrane surface rather than inside pores. The ATR-FTIR and atomic force microscopy (AFM) were used to characterize the photografting polymerization and the configuration of membrane pores in different conditions. The membrane pores are regulated by the grafted poly(4-vinylpyridine) chains, which give a pore-covering effect by stretching over or into the pores. The water fluxes of the grafted membranes have great leap near the pH range of 2–4 even with a very low grafting degree (0.3 wt%). Moreover, the fluxes approximate to that of blank membrane in neutral solution (open state), and close to zero in acidic solution (close state). Different from poly(acrylic acid) grafted membranes, the poor water solubility of poly(4-vinylpyridine) makes the grafting chains float on the surface of water inside pores and no obvious open and close configuration of the membrane pores were observed under AFM. The filtration test indicated that grafted membranes have no retention to both riboflavin and bovine serum albumin (BSA) under pressure driving, whereas diffusion tests showed that both in open and close states, the BSA could be trapped completely at high grafting degree (more than 2.54%) while riboflavin can freely diffuse through the membranes.
Co-reporter:Yongxin Wang;Jianping Deng;Wenbin Zhong;Lingbing Kong
Macromolecular Rapid Communications 2005 Volume 26(Issue 22) pp:1788-1793
Publication Date(Web):31 OCT 2005
DOI:10.1002/marc.200500444
Summary: Superhydrophilic modification of poly(propylene) and poly(ethylene terephthalate) films' surfaces was realized by the UV-initiated surface photografting of a N-vinyl pyrrolidone/N,N′-methylenebisacrylamide inverse microemulsion. AFM characterization of the treated films' surface revealed that it was the grafted quasi-bimodal (ca. 45 and 110 nm) particles of cross-linked poly(N-vinyl pyrrolidone) that led to superhydrophilicity of the surface. The grafted nanometer-scale particles showed little influence on the transparency of the substrate's surface, but endowed long-term stability to the superhydrophilicity.
Co-reporter:Yongxin Wang;Wenbin Zhong;Nan Jiang
Macromolecular Rapid Communications 2005 Volume 26(Issue 2) pp:87-92
Publication Date(Web):19 JAN 2005
DOI:10.1002/marc.200400488
Summary: A sequential two-step method was successfully used for the photografting of methyl methacrylate/1,2-divinylbenzene (MMA/DVB) microemulsion onto the surface of a poly(propylene) (PP) film. Atomic force microscopy (AFM) images showed that nanoparticles with a cross-section diameter of 60 nm were directly grafted onto the substrate's surface. Environment scanning electron microscope (ESEM) images proved that the particles formed just a single layer on the surface. The dormant groups on the nanoparticles' surface were a potential factor in the evolution of single layer into multilayer nanoparticles.
Co-reporter:Wenbin Zhong;Jianyuan Deng;Yongsheng Yang;Yongsheng Yang;Wenbin Zhong;Jianyuan Deng
Macromolecular Rapid Communications 2005 Volume 26(Issue 5) pp:395-400
Publication Date(Web):23 FEB 2005
DOI:10.1002/marc.200400463
Summary: Three-dimensional polyaniline (PANI) nanowire networks were synthesized in high yield using a “soft template” self-assembled with hexadecyltrimethylammonium bromide and oxalic acid. The PANI nanowire networks had diameters from 35–100 nm depending on synthesis conditions and/or procedures. The networks and the “cross-linking points” were clearly observed by field-emission scanning electron microscopy and transmission electron microscopy. A possible mechanism for the formation of three-dimensional PANI nanowire networks is discussed.
Co-reporter:Yongsheng Yang
Polymers for Advanced Technologies 2005 Volume 16(Issue 1) pp:24-31
Publication Date(Web):20 DEC 2004
DOI:10.1002/pat.541
In the presence of acrylic acid (AA) as a primary dopant, polyaniline (PANI) doped with poly(acrylic acid) was successfully synthesized by using ammonium persulfate (APS) as initiator and oxidizing agent. The effect of experimental conditions on the polymer yields was systematically studied. It was found that the polymer yield can be as high as 65%, and this value strongly depends on synthesis conditions, such as the reaction time, the molar ratio of oxidizing agent to aniline monomer, the concentration of reactants and reaction temperature. The molecular weight () of main chains of the de-doped PANI is estimated to be 32,000–53,000. Based on the data of FT-IR, UV-vis, 13C-nuclear magnetic resonance (NMR), elemental analysis and electrical conductivity measurement, the emeraldine salt form of PANI was confirmed and the molecular structure of the resulting PANI-AA was proposed. Accordingly the reaction mechanism was discussed and it was convinced that the polymerization reaction of AA is initiated by APS. Copyright © 2004 John Wiley & Sons, Ltd.
Co-reporter:Chang-Min Xing;Jian-Ping Deng;Wan-Tai Yang
Macromolecular Chemistry and Physics 2005 Volume 206(Issue 11) pp:1106-1113
Publication Date(Web):23 MAY 2005
DOI:10.1002/macp.200400534
Summary: A polymeric surface with desirable wettability and versatile reactivity was facilely fabricated by UV-induced surface photografting of N-vinylpyrrolidone (NVP)/maleic anhydride (MAn) binary monomers, with polypropylene (PP) film as a model substrate. It was found that the photografting process of NVP/MAn is much faster than that of individual NVP or MAn; both the grafting efficiency (Eg) and grafting yield (Yg) reach a maximum at around 1:1 molar feed ratio of NVP to MAn. These results indicate that the electron donor-acceptor monomers can synergistically promote surface photografting by a known charge-transfer-complex (CTC) mechanism. Moreover, the grafted NVP and MAn units cooperatively enhance the surface hydrophilicity; the water contact angle of the modified surface drastically decreases from the original 99.4° to less than 36° within 30 s of irradiation time. Subsequently, we demonstrated that the surface-grafted succinic anhydride groups could readily perform a variety of organic reactions such as acidic/alkaline hydrolysis and esterification, which is expected to facilitate further surface functionalizations. Besides, the complexing reaction of surface pyrrolidone groups with iodine was investigated, which was followed by UV-vis spectroscopy. The antimicrobial activity against Escherichia coli, Staphylococcus aureus and Candida albicans show that this unique iodine-complexated surface has desirable antimicrobial property.
Co-reporter:Deng Jianping;Yang Wantai
Journal of Applied Polymer Science 2005 Volume 95(Issue 4) pp:903-909
Publication Date(Web):21 DEC 2004
DOI:10.1002/app.21219
In previous studies, the photografting polymerization of vinyl acetate (VAC) and maleic anhydride (MAH) was investigated systematically. After that, to increase the grafting rate and efficiency and make the project more practicable, a VAC–MAH binary monomer system was employed for simultaneous photografting onto the surface of low-density polyethylene film. The effects of several crucial factors, including the composition and total concentration of the monomer solution and different types of photoinitiators and solvents, on the grafting polymerization were investigated in detail. The conversion percentage (CP), grafting efficiency (GE), and grafting percentage were measured by gravimetry. The results showed that the monomer composition played a big part in this binary system; appropriately increasing the content of MAH in the monomer feed was suited for grafting polymerization. The growth of the total monomer concentration, however, made the copolymerization faster and was unfavorable for grafting polymerization. The three photoinitiators—2,2-dimethoxy-2-phenylacetophenone (Irgacure 651), benzoyl peroxide, and benzophenone (BP)—led to only slight differences in CP, but for GE, BP was the most suitable. As for the different solvents—acetone, ethyl acetate, tetrahydrofuran (THF), and chloroform—using those able to donate electrons (acetone and THF) resulted in relatively higher CPs; on the contrary, the use of the other solvents made GE obviously higher, and this should be attributed to the charge-transfer complex (CTC) that formed in this system. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 903–909, 2005
Co-reporter:Deng Jianping;Yang Wantai
Journal of Applied Polymer Science 2005 Volume 95(Issue 4) pp:910-915
Publication Date(Web):21 DEC 2004
DOI:10.1002/app.21236
The photografting copolymerization of a low-density polyethylene/vinyl acetate (VAC)–maleic anhydride (MAH) binary monomer system was studied from the perspective of dynamics. The total conversion percentage (CP) and grafting conversion percentage (CG) were measured by gravimetry. On the basis of plots of CP and CG as functions of the polymerization time, the total polymerization rate (RP) and grafting polymerization rate (RG) were calculated. In addition, the apparent activation energy (Ea) and the reaction orders of the photografting polymerization under different reaction conditions, such as the total monomer concentration and the concentration of benzophenone (BP), were determined also. The results showed that, in comparison with the photografting polymerization of the two single monomers (VAC and MAH), RP and RG noticeably increased for the VAC–MAH binary monomer system. When the total monomer concentration was kept at 4M, the apparent Ea's of the three photografting polymerization systems were as follows: for VAC ([MAH]/[VAC] = 0/4), Ea's for the total polymerization and grafting polymerization were 41.00 and 43.90 kJ/mol, respectively; for MAH ([MAH]/[VAC] = 4/0, Ea's were 39.65 and 43.23 kJ/mol, respectively; and for the VAC–MAH binary monomer system, Ea's were 34.35 and 40.32 kJ/mol, respectively. These results suggested that the polymerization of the binary system occurred more readily than the other two. The reaction orders of RP with respect to the total monomer concentration of the monomers and the concentration of BP were 1.34 and 0.81, respectively. According to these investigations, it could be inferred that in the binary monomer system, both the free monomers and charge-transfer complex took part in the polymerization; to the termination of the propagating chains, two possible pathways, unimolecular termination and bimolecular termination, coexisted in this binary monomer system. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 910–915, 2005
Co-reporter:Chang-Min Xing;Jian-Ping Deng;Wan-Tai Yang
Journal of Applied Polymer Science 2005 Volume 97(Issue 5) pp:2026-2031
Publication Date(Web):23 JUN 2005
DOI:10.1002/app.21853
A novel antibacterial material with surface immobilized polyvinylpyrrolidone-iodine complex was synthesized facilely by a two-step approach. First, N-vinylpyrrolidone (NVP) was photografted onto polymeric substrates, and subsequently the surface-grafted polyvinylpyrrolidone (PVP) underwent complexation of iodine. In the UV-induced photografting process, PVP was efficiently grafted onto the polypropylene (PP) film surface by a unique film interlayer photopolymerization (FIP) technique; the grafting yield (Yg) could be controlled by varying the irradiation time or the monomer concentration. Further, we demonstrated that the grafted PVP chains could readily perform the complexation reaction with iodine as the homopolymer PVP does, which was characterized by UV–vis spectroscopy. The antibacterial activity of the modified polymer against Escherichia coli, Staphylococcus aureus, and Candida albicans was investigated. The results show that the modified PP film with surface-immobilized PVP-I complex has a desirable antibacterial property, with broad spectrum and high efficiency. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2026–2031, 2005
Co-reporter:Deng Jianping;Yang Wantai
Journal of Applied Polymer Science 2005 Volume 97(Issue 6) pp:2230-2237
Publication Date(Web):28 JUN 2005
DOI:10.1002/app.21877
The two-step method was employed to obtain insight into the grafting mechanism of (MAH-VAC)/LDPE film in the preceding investigation, where photoreduction of BP (the first step) was investigated and the subsequent grafting polymerization (the second step) was studied from the viewpoint of kinetics. The present article is devoted to investigation of the living polymerization performance, the compositions of the grafted chains, and the relevant grafting copolymerization mechanism of the (MAH-VAC)/LDPE system. Both grafting copolymerization and nongrafting copolymerization performed living polymerization characteristics to some degree. Regarding the nongrafting copolymerization at a monomer concentration, [MAH] = [VAC] = 2M, MAH and VAC mainly underwent alternating copolymerization, especially at low temperatures; however, the grafting copolymerization mostly exhibited random copolymerization, which became obvious with the elevation of temperature. The composition of the monomer feed largely affected the composition of the grafted copolymer and the nongrafted copolymer. When [MAH]/[VAC] was either 2.5/1.5, 2/2, or 1.5/2.5, MAH/VAC in nongrafted copolymers stayed approximately at 1/1; while when [MAH]/[VAC] was 2.5/1.5, MAH/VAC in the grafted copolymer was nearly 1/1; but in the case of [MAH]/[VAC] being 2/2 and 1.5/2.5, the content of MAH in grafted chains was somewhat lower than that of VAC. All these results demonstrated that the grafting copolymerization on the substrate occurred randomly, which was greatly affected by the affinity of the monomer toward the substrate. This performance of the grafting copolymerization was much different from the nongrafting copolymerization in the solution. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2230–2237, 2005
Co-reporter:Chang-Min Xing;Wan-Tai Yang
Journal of Polymer Science Part A: Polymer Chemistry 2005 Volume 43(Issue 17) pp:3760-3770
Publication Date(Web):11 JUL 2005
DOI:10.1002/pola.20871
A novel dispersion copolymerization of maleic anhydride (MAn) and vinyl acetate (VAc) without adding stabilizer is developed, which gives uniform copolymer microspheres with tunable sizes. Some principal factors affecting the microspheres, such as reaction time, monomer concentration and feed ratio, reaction media, and cosolvent, were investigated. It was found that the stabilizer-free dispersion copolymerization of MAn and VAc is a rapid process, and the particle size grows in accordance with the evolution of polymerization. The chemical composition of the copolymer microspheres was characterized by FT-IR and 13C NMR spectroscopies. Over a wide range of monomer concentrations, the microspheres can always be formed and stably dispersed, with uniform sizes ranging from 180 nm to 740 nm. The yield of copolymer microspheres reaches a maximum at 1:1 feed ratio of MAn to VAc, owing to the alternating copolymerization between the binary monomers by a known charge-transfer-complex mechanism. However, the diameter of microspheres drastically increases when MAn content is enhanced. Only some specific alkyl ester solvents, such as n-butyl acetate, isobutyl acetate, n-amyl acetate, are desirably fit for this unique stabilizer-free dispersion polymerization. Furthermore, we found that when some acetone is added as a cosolvent, the copolymer microspheres can still be formed, with much larger diameters. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3760–3770, 2005
Co-reporter:Wenbin Zhong, Yongsheng Yang, Wantai Yang
Thin Solid Films 2005 Volume 479(1–2) pp:24-30
Publication Date(Web):23 May 2005
DOI:10.1016/j.tsf.2004.11.105
A method for the preparation of electrically conductive poly(propylene) -graft-polyacrylic acid/polyaniline (PP-g-PAA/PANI) composite films was developed. The synthesis was mainly performed by two steps, i.e., the surface graft copolymerization of PP films with acrylic acid induced by ultraviolet (UV) and then chemical oxidative polymerization of aniline. The influence of experimental conditions on graft percentage of PANI on PP-g-PAA films was systematically investigated. It was found that when the polymerization on the surface of PP-g-PAA films was performed in aqueous HCl medium, the optimum aniline concentration was 0.1 M at pH 1. Additionally, UV–visible spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy were used to characterize and analyze the interaction between PAA and aniline, the formation mechanism and the surface structure of the PP-g-PAA/PANI films. The morphologies of the PP-g-PAA/PANI composite films were also detected by scanning electron microscope. The conductivity and the thickness of the composite films with 2 wt.% PANI were about 10−2S/cm and 0.6 μm, respectively.
Co-reporter:Chang-Min Xing;Wan-Tai Yang
Macromolecular Rapid Communications 2004 Volume 25(Issue 17) pp:1568-1574
Publication Date(Web):25 AUG 2004
DOI:10.1002/marc.200400230
Summary: A novel, stabilizer-free dispersion polymerization with alkyl esters as reaction media gives uniform alternating microspheres of maleic anhydride (MAn)/vinyl acetate (VAc) copolymer. The diameter of the copolymer microspheres could be precisely controlled from 80 to 750 nm by changing the monomer concentration or feed ratio. Moreover, this new type of copolymer microspheres with reactive anhydride groups on the surface has good solubility in common nontoxic solvents such as water and ethanol.
Co-reporter:Lin Tan;Jianping Deng
Polymers for Advanced Technologies 2004 Volume 15(Issue 9) pp:523-527
Publication Date(Web):31 AUG 2004
DOI:10.1002/pat.503
A facile and environment friendly approach was developed to graft vinyl acetate (VAc) onto plastic articles in an aqueous solution using tert-butyl alcohol (TBA) as a compatiblizer and benzoyl peroxide (BPO) as an initiator. In a novel setup, excessive monomer suspended in a water phase, VAc could be conveniently grafted on the model substrate of low-density polyethylene (LDPE) film and the graft percentage (GP) could be developed up to 7.3%. Reaction temperature could increase GP significantly, while adding monomer over a critical volume did not influence GP. By adding some paradioxybenzene, i.e. 0.06–0.08% in VAc phase, homopolymer PVAc could be avoided practically, while graft polymerization proceeded favorably in aqueous solutions. It was proved by attenuated total reflection-infrared (ATR-IR) spectroscopy that grafted VAc was located mainly at the surface of the LDPE film and hydrophilic nature of both grafted and alcoholyzed films were improved via contact angle measurements. Copyright © 2004 John Wiley & Sons, Ltd.
Co-reporter:Peng Yang;Jianyuan Deng
Macromolecular Chemistry and Physics 2004 Volume 205(Issue 8) pp:
Publication Date(Web):13 MAY 2004
DOI:10.1002/macp.200300248
Summary: It was found that without additional photoinitiator, methyl methacrylate (MMA) dissolved in common solvent N,N-dimethylformamide (DMF) could be photografted steadily on low-density polyethylene (LDPE) film surface under UV irradiation. In short irradiation time (4 min) and at room temperature, high grafting efficiency (approaching 100%) and remarkable graft polymer amount (grafting percent is about 4.6%) was obtained. The possible reaction mechanism was based on the photosensitivity of DMF, which induced this photografting polymerization. This finding is useful to develop photoinitiator-free grafting or photopolymerization system. Using SEM, special discrete globular structure was found on the MMA-grafted LDPE film surface, and a possible model was proposed to interpret it.
Co-reporter:Wantai Yang;Lianying Liu
Journal of Polymer Science Part A: Polymer Chemistry 2004 Volume 42(Issue 4) pp:846-852
Publication Date(Web):2 JAN 2004
DOI:10.1002/pola.11033
The kinetics of photoinitiated, inverse emulsion polymerization of acrylamide with 2,2-dimethoxy-2-phenylacetophenone (DMPA) as a photoinitiator was investigated under three different cases. First, in a quartz reactor transparent to full UV light, the polymerization rate (Rp) increased and then decreased with the change of initiator order from 0.27 to a negative value when the DMPA concentration was increased, and it was particularly unusual that monomer orders at different DMPA concentrations were lower than the first. Second, for polymerization without DMPA in a quartz reactor, the dependence of Rp on monomer concentration was similar to that of Rp on initiator concentration in the aforementioned case. Third, when polymerization was carried out in a Pyrex reactor where the far UV light was filtered, a peak rate was also observed, and initiator orders varied from 0.24 to a negative value; however, under this case monomer orders at different initiator concentrations were greater than the first. These results indicated that the effect of absorbance often observed in bulk or solution photopolymerization also existed in this system, and the self-initiation of monomer had some influence on polymerization, and the role of primary radical termination could not be neglected, as evidenced by kinetic analysis. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 846–852, 2004
Co-reporter:Yuhong Ma
Journal of Polymer Science Part A: Polymer Chemistry 2004 Volume 42(Issue 11) pp:2678-2685
Publication Date(Web):23 APR 2004
DOI:10.1002/pola.20118
The nonaqueous dispersion polymerization of styrene in methanol with poly[(4-methylstyrene)-co-(4-vinyltriethylbenzyl ammonium bromide)]-b-polyisobutene as a stabilizer was investigated. There was no observable inducing period or autoacceleration in the polymerization process. The conversion increased almost linearly with the polymerization time as high as 80%. The average sizes of the obtained polystyrene particles increased, and the size distributions of the polystyrene particles tended to become narrower, with increasing conversion. The mechanism of the dispersion polymerization in the presence of polyisobutene-b-poly[(4-methylstyrene)-co-(4-vinyltriethylbenzyl ammonium bromide)] was nucleation/growth. When the stabilizer/monomer ratio (w/w) was greater than 2.0%, the polystyrene dispersion was stable, and there was no observable polymer particle coagulation taking place during the whole polymerization process. The average diameter of the polymer particles can be mediated through changes in the polymerization conversion, monomer, and stabilizer. Nearly monodispersed polystyrene particles with average diameters of approximately 0.45–2.21 μm were obtained under optimal conditions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2678–2685, 2004
Co-reporter:Peng Yang;Yufeng Sun;Jianyuan Deng;Li Zhang;Weina Liu
Journal of Polymer Science Part A: Polymer Chemistry 2004 Volume 42(Issue 16) pp:4074-4083
Publication Date(Web):9 JUL 2004
DOI:10.1002/pola.20238
The synthesis of a polymer-supported inhibitor (PSI) and its inhibition performance for free-radical polymerization are reported for the first time. A special method has been devised to synthesize PSI with pure and abundant hydroquinone (HQ) groups anchored onto the polymer surface. A thin HQ/acetone (AC) solution is sandwiched between two polymer films. Under ultraviolet irradiation, AC as an photoinitiator quickly and effectively grafts HQ onto the polymer surface. PSI has been characterized with ultraviolet–visible and attenuated total reflectance/Fourier transform infrared spectroscopy. For potential applications, PSI has been used to inhibit the thermal polymerization of styrene and methyl methacrylate. The corresponding inhibition performance has been investigated through the measurement of the induction period with the dilatometer method. With the same absolute amount, the maximum inhibition ability of PSI approaches half that of a free inhibitor. Increasing the dispersion degree of PSI is favorable for the enhancement of the inhibition ability. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4074–4083, 2004
Co-reporter:Biao Yang, Wantai Yang
Journal of Membrane Science 2003 Volume 218(1–2) pp:247-255
Publication Date(Web):1 July 2003
DOI:10.1016/S0376-7388(03)00182-0
Novel thermo-sensitive switching membrane regulated by pore-covering polymer brushes was prepared by photografting N-isopropylacrylamide (NIPAAm) onto the polyethylene terephthalate (PET) track membranes with benzophenone (BP) as initiator. The influence of solvent, initiator concentration and temperature on photografting has been investigated. ATR-FTIR and SEM confirmed that poly-NIPAAm brushes were immobilized on the membranes surface exposed to the UV light instead of inside the pores. The thickness of grafted layer can be adjusted by grafting reaction parameters via grafting degree. The membrane flux is regulated by pore-covering effect that comes from the grafted chains’ stretching into the membrane pores. Responding to the change of the temperature, the pore size varied with the swelling and shrinkage of poly-NIPAAm brushes and accordingly adjusted the membranes flux. The 0.2 μm-grafted membranes do not show a remarkable thermo-sensitive valve effect near the range of 30–35 °C until the grafting degree exceeds 1%. To 0.4 μm membrane, the grafted brushes are not long enough to cover the membrane pores and thus crosslink agent is necessary. The crosslink network limit the free movement of grafted polymer brushes and thus the critical temperature has a shift to high temperature.
Co-reporter:Yuhong Ma;Guanying Wu
Journal of Polymer Science Part A: Polymer Chemistry 2003 Volume 41(Issue 3) pp:408-412
Publication Date(Web):12 DEC 2002
DOI:10.1002/pola.10591
A novel method of synthesizing a clean diblock copolymer via cationic polymerization was developed. First, a poly(4-methylstyrene) macroinitiator was prepared, and then a second comonomer (isobutene) and a coinitiator (AlEt2Cl) were added for the initiation of block copolymerization.
Co-reporter:Jianping Deng, Weiguo Zhao, Wantai Yang
Reactive and Functional Polymers (September 2007) Volume 67(Issue 9) pp:828-835
Publication Date(Web):September 2007
DOI:10.1016/j.reactfunctpolym.2006.12.009
Co-reporter:Xianhong Zhang, Sidi Zhao, Fang Wang, Yuhong Ma, Li Wang, Dong Chen, Changwen Zhao, Wantai Yang
Applied Surface Science (1 May 2017) Volume 403() pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.apsusc.2017.01.121
•Core-shell structured BT@PMMA and BT@PTFEMA nanoparticles were synthesized.•The dispersity of BT nanoparticles in PVDF matrix was improved significantly.•Dielectric properties both of BT@PMMA/PVDF and BT@PTFEMA/PVDF composites were improved.•The frequency dependence of dielectric constant attenuation of BT@PTFEMA/PVDF composites was smaller than that of BT@PMMA/PVDF composites.Polymer based dielectric composites were fabricated through incorporation of core-shell structured BaTiO3 (BT) nanoparticles into PVDF matrix by means of solution blending. Core-shell structured BT nanoparticles with different shell composition and shell thickness were prepared by grafting methacrylate monomer (MMA or TFEMA) onto the surface of BT nanoparticles via surface initiated atom transfer radical polymerization (SI-ATRP). The content of the grafted polymer and the micro-morphology of the core-shell structured BT nanoparticles were investigated by thermo gravimetric analyses (TGA) and transmission electron microscopy (TEM), respectively. The dielectric properties were measured by broadband dielectric spectroscopy. The results showed that high dielectric constant and low dielectric loss are successfully realized in the polymer based composites. Moreover, the type of the grafted polymer and its content had different effect on the dielectric constant. In detail, the attenuation of dielectric constant was 16.6% for BT@PMMA1/PVDF and 10.7% for BT@PMMA2/PVDF composite in the range of 10 Hz to 100 kHz, in which the grafted content of PMMA was 5.5% and 8.0%, respectively. However, the attenuation of dielectric constant was 5.5% for BT@PTFEMA1/PVDF and 4.0% for BT@PTFEMA2/PVDF composite, in which the grafted content of PTFEMA was 1.5% and 2.0%, respectively. These attractive features of BT@PTFEMA/PVDF composites suggested that dielectric ceramic fillers modified with fluorinated polymer can be used to prepare high performance composites, especially those with low dielectric loss and high dielectric constant.
Co-reporter:Linyue Tong, Xin Cui, Wantai Yang and Jianping Deng
Journal of Materials Chemistry A 2012 - vol. 22(Issue 14) pp:
Publication Date(Web):
DOI:10.1039/C2JM15652K
Co-reporter:Xiaofeng Luo, Lei Li, Jianping Deng, Tiantian Guo and Wantai Yang
Chemical Communications 2010 - vol. 46(Issue 16) pp:NaN2747-2747
Publication Date(Web):2010/03/17
DOI:10.1039/B926134F
Achiral substituted acetylene monomers undergo aqueous catalytic emulsion asymmetric polymerizations in chiral micelles consisting of SDS and amino acid, providing optically active helical polymer emulsions. The asymmetric polymerizations lead to one-handed helical polymers, which are the origin of the optical activity of polymer emulsions.
Co-reporter:Kang Zhou, Linyue Tong, Jianping Deng and Wantai Yang
Journal of Materials Chemistry A 2010 - vol. 20(Issue 4) pp:NaN789-789
Publication Date(Web):2009/11/30
DOI:10.1039/B918132F
A novel class of hollow polymeric microspheres was prepared from optically active helical polymers. To prepare the hollow spheres, optically active helical N-propargylamide copolymers (OAHPs) containing specially designed CC groups in pendent groups, were first synthesized and subsequently used as a macromonomer. Polymeric particles based on maleic anhydride (MAH) and vinyl acetate were prepared and used as sacrificial templates for the subsequent preparation of core/shell spheres, which were accomplished by using the system consisting of MAH, divinyl benzene and OAHP macromonomers. After extracting the core in the prepared core/shell particles, hollow microspheres grafted with optically active helical polymer chains were successfully obtained. The hollow particles were characterized with FTIR, field-emission SEM and TEM measurements. The size and the shell thickness of these hollow spheres were readily controllable. Circular dichroism (CD) spectra were recorded on the hollow spheres dispersed in THF. The intense CD effects indicated that the hollow spheres possessed high optical activity, arising from the helical polymer chains. The preferential adsorption of (R)-(+)-1-phenylethylamine to the (S)-form by the obtained hollow spheres clearly attested to the chiral recognition ability of the novel spheres.
Co-reporter:Lihua Zhang, Yuhong Ma, Changwen Zhao, Xing Zhu, Ruichao Chen and Wantai Yang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 39) pp:NaN7681-7681
Publication Date(Web):2015/08/10
DOI:10.1039/C5TB01149C
A new visible light induced graft polymerization method was utilized to prepare pH-sensitive hydrogel layers covalently attached to polymer substrates for drug delivery. In our strategy, isopropyl thioxanthone semi-pinacol (ITXSP) dormant groups were firstly introduced on the surface of a polycaprolactone (PCL) film by a UV-induced abstracting hydrogen-coupling reaction. Then visible light induced graft cross-linking polymerization was performed to initiate polymerization of poly(ethylene glycol) diacrylate (PEGDA) and acrylic acid (AA), resulting in the formation of a hydrogel layer. The thickness of the hydrogel film can be controlled by varying the exposure time and monomer composition. The grafted hydrogel layers showed a flat morphology and dense structure, which is different from the traditional reported porous structure. The water contact angle of the hydrogel layer exhibited a reversible change from 38° to 18° when the film was alternatively treated in buffers of pH 2.0 and 7.4, respectively. Patterned hydrogel layers were prepared as a model to determine the change in the height of the grafted hydrogel layer as a function of pH. As the pH changed from 2.0 to 7.4, the hydrogel pattern showed an increase in height due to the swelling of the hydrogel network, and the hydrogel layer formed by 0.2 wt% PEGDA and 25 wt% AA showed the most increase (30%) in height. Bovine serum albumin (BSA) and lysozyme as models of protein drugs were incorporated in the hydrogel network, and their release also showed obvious pH-sensitivity. At pH 2.0, hydrogels present a faster initial burst release due to the squeezing mechanism. Tertiary structure analysis showed that encapsulation and release did not affect the protein conformation. These findings have improved our understanding of hydrogel thin films, which may be useful as potential vehicles of therapeutic proteins in drug delivery applications.
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