Co-reporter:Jiaxing Zhang, Hongying Shen, Wenguang Song, and Guowei Wang
Macromolecules April 11, 2017 Volume 50(Issue 7) pp:2683-2683
Publication Date(Web):March 30, 2017
DOI:10.1021/acs.macromol.7b00159
A series of novel linear and hyperbranched copolymers with different topological structures and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical distributions were synthesized, and their paramagnetic property was systematically investigated. Based on the ring-opening polymerization (ROP) mechanism of GTEMPO, glycidol (Gly) or ethylene oxide (EO) monomers, the linear Poly(EO-co-GTEMPO) and hyperbranched Poly(Gly-co-GTEMPO) copolymers were obtained from a bifunctional 2,2-dimethyl-1,3-propanediol initiator and a tetrafunctional pentaerythritol initiator, respectively. Alternatively, from the multifunctional macroinitiator of hyperbranched polyglycerol (HPG), the hyperbranched HPG-g-Poly(Gly-co-GTEMPO) and HPG-g-PGTEMPO copolymers were also targeted. The copolymers were characterized by GPC, DSC, and UV–vis analysis. The paramagnetic property of the copolymers was studied and compared by EPR analysis at different concentrations of copolymers and temperatures. The results displayed that the concentrations of copolymers majorly manipulated the signal intensity of EPR spectra, and the temperature majorly modulated the shape of EPR spectra. Essentially, the TEMPO radical distributions in copolymers played an important role: the higher regional density tended to give the EPR spectra with intense, broad peaks, while the lower one led to the regular, well-pronounced EPR spectra. The difference was rationalized to different intramolecular spin–spin exchange and dipole–dipole interaction modulated by the topological structures and the corresponding TEMPO radical distributions.
Co-reporter:Jian Wang;Zhigang Wu;Hongying Shen
Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 45) pp:7044-7053
Publication Date(Web):2017/11/21
DOI:10.1039/C7PY01683B
Bottle-brush copolymers poly(2-hydroxyethyl methacrylate)(PHEMA)-g-{[(poly(acrylic acid)-g-2,2,6,6-tetramethylpiperidine-1-oxyl)]-b-poly(methyl acrylate)} (PHEMA-g-[(PAA-g-TEMPO)-b-PMA]) and PHEMA-g-(PAA-g-TEMPO) with shielding 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radicals were synthesized, and their paramagnetic properties were compared in bulk and solution, respectively. Firstly, using a “grafting from” strategy, the atom transfer radical polymerization (ATRP) of tert-butylacrylate (tBA) permitted the successful synthesis of the bottle-brush copolymer PHEMA-g-PtBA from the macro-initiator poly[2-(2-bromoisobutyryloxy)ethyl methacrylate] (PBiBEMA) with a high density of initiating sites. Subsequently, following a second “grafting from” strategy and the ATRP of methyl acrylate (MA), the bottle-brush copolymer PHEMA-g-(PtBA-b-PMA) was further produced by employing PHEMA-g-PtBA as the macro-initiator. The poly(acrylic acid) (PAA) segment generated by the selective hydrolysis of the PtBA segment was used to introduce TEMPO radicals through the reaction between carboxyl groups on PAA and oxirane group on glycidoloxy-2,2,6,6-tetramethyl piperidine-1-oxyl (GTEMPO). With the shielding by the outer PMA segment in PHEMA-g-[(PAA-g-TEMPO)-b-PMA], superfine information of inner TEMPO radicals in the electron paramagnetic resonance (EPR) spectrum could be well discriminated. However, the PHEMA-g-(PAA-g-TEMPO) without any shielding showed a broad EPR spectrum, which was in accordance with a characteristic EPR spectrum of a polyradical polymer due to the strong interactions between radicals.
Co-reporter:Hongying Shen
Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 36) pp:5554-5560
Publication Date(Web):2017/09/19
DOI:10.1039/C7PY01034F
Cyclic polymers have been confirmed to possess unique properties and have potential in different applications due to the absence of free end groups. However, efficient synthesis of cyclic polymers remains a significant challenge. In this context, a versatile flash cyclization technique assisted by a microreactor (or micromixer) is presented. Unlike the conventional batch system procedure, the cyclization of linear poly(ethylene oxide) (l-PEO) can be instantly and completely realized in a micromixer. Successful cyclization can also be accomplished with an elevated flow rate of l-PEO and/or catalyst solution. Based on the flash character of the microreaction system, an upgraded setup is also constructed by introducing a circulation loop to recycle the catalyst solution. The cyclization time is therefore considerably shortened and the consumption of solvent is greatly reduced, which provides a significant improvement in cyclization efficiency.
Co-reporter:Xinyi Liang, Yujie Liu, Jian Huang, Liuhe Wei and Guowei Wang
Polymer Chemistry 2015 vol. 6(Issue 3) pp:466-475
Publication Date(Web):19 Sep 2014
DOI:10.1039/C4PY01225A
Novel barbwire-like graft polymers PEO-g-PCL4 were synthesized by combination of ring opening polymerization (ROP) and Glaser coupling with thiol–yne addition reaction via the “grafting from” strategy. Typically, the precursor (PEO-diyne-PEO)s of high molecular weight was obtained by Glaser coupling of alkyne-PEO-alkyne, which was prepared by modification of HO-PEO-OH with propargyl bromide. After the diyne groups on PEO were transferred into hydroxyl groups by efficient thiol–yne addition reaction with mercaptoethanol, the macroinitiator [PEO-(OH)4-PEO]s was obtained and the graft polymers PEO-g-PCL4 were synthesized by ROP of ε-caprolactone monomers. The structure of graft polymers was confirmed by GPC, MALDI-TOF MS, 1H NMR, and TGA measurements in detail, and the crystallization behavior of graft polymers was also comprehensively investigated using DSC, WAXD, and POM instruments.
Co-reporter:Yujie Liu, Xuepu Wang, Wenguang Song and Guowei Wang
Polymer Chemistry 2015 vol. 6(Issue 43) pp:7514-7523
Publication Date(Web):08 Sep 2015
DOI:10.1039/C5PY01190F
A series of novel silica nanoparticles functionalized with multiple TEMPO groups were synthesized using a novel, efficient and versatile protocol. First, the amino-functionalized silica nanoparticles (SN-NH2) were obtained using an improved one-pot hydrolysis and co-condensation procedure of APTES and TEOS agents, and further modified with 2-bromoisobutyryl bromide for macro-initiator (SN-Br) by amidation reaction. Then, the polymer grafted silica nanoparticles (SN-g-PGMA) with a dense shell layer of PGMA side-chains were realized via the surface-initiated atom transfer radical polymerization (SI-ATRP) procedure in a controlled manner. Subsequently, the azido groups were introduced onto PGMA side-chains by the quantitative ring-opening reaction of an epoxide with a sodium azide agent, and the TEMPO groups were further attached by efficient “Click” chemistry with propargyl-TEMPO for the target SN-g-(PGMA-TEMPO). The evidence for the successful synthesis of target polymers and intermediates was sufficiently provided by FT-IR, EPR, XPS, TEM, 1H NMR, and TGA measurements. As an important task, the catalytic activity of the synthesized SN-g-(PGMA-TEMPO) was evaluated by the oxidation of benzylic alcohols according to the Anelli protocol, as well as the excellent efficiency, stability and recyclability of the catalyst were also confirmed.
Co-reporter:Wenguang Song, Jian Huang, Cheng Hang, Chenyan Liu, Xuepu Wang and Guowei Wang
Polymer Chemistry 2015 vol. 6(Issue 46) pp:8060-8070
Publication Date(Web):28 Sep 2015
DOI:10.1039/C5PY01493J
Based on the common features of well-defined nitroxide radical coupling (NRC) reaction, atom transfer radical polymerization (ATRP) and nitroxide mediated radical polymerization (NMRP) mechanisms, an atom transfer nitroxide radical polymerization (ATNRP) mechanism was presented by integrating these three mechanisms into one polymerization system simultaneously, and further used to construct multisegmented polystyrene (PSm) embedded with multiple alkoxyamine linkages. The initiator 1-oxyl-2,2,6,6-tetramethylpiperidinyl-4-yl 2-bromo-2-methylpropanoate (Br-TEMPO) containing one bromoisobutyryl group and one stable nitroxide radical was firstly designed and synthesized. Then, the ATNRP mechanism was systematically investigated by optimizing factors such as polymerization temperature, solvent, catalyst, time and operation technology. The results showed that the NRC reaction, ATRP and NMRP mechanisms can synergistically proceed in ATNRP due to the thermally reversible dissociation–combination behavior of the formed alkoxyamine linkages, and the polymerization temperature and solvent were the key factors. Finally, the thermal behaviour of the formed PSm was monitored by TGA and DSC analyses. The result showed that the alkoxyamine linkages can undergo a thermal cleavage at an elevated temperature of 110 °C and the PSm can be cleaved in the presence of excess stable nitroxide radicals. The PSm embedded with multiple alkoxyamine linkages and the cleaved PS possessing one nitroxide radical have the same thermal stability, however the Tg of PSm gradually approached that of the cleaved PS when several heating–cooling (40–150 °C) cycles were performed. Due to the versatile functions of the as-prepared PSm and cleaved PS, this ATNRP mechanism will hopefully find more potential applications in polymer chemistry.
Co-reporter:Lingdi Chen, Jiaxing Zhang, Yujie Liu, Hongdong Zhang and Guowei Wang
Polymer Chemistry 2015 vol. 6(Issue 48) pp:8343-8353
Publication Date(Web):05 Oct 2015
DOI:10.1039/C5PY01103E
Several novel multiblock copolymers, (PEO-b-PS-b-PEO-Diyne)s, [PEO-b-PS-b-PEO-(OH)4]s and (PEO-b-PS-b-PEO-Acetal)s, with the same compositions but different linkages were constructed, and their micellization and application were studied. First, the precursor HO-PEO-b-PS-b-PEO-OH was prepared by sequential LAP and ROP mechanisms, and the precursor Propargyl-PEO-b-PS-b-PEO-Propargyl was achieved by a subsequent modification procedure. Subsequently, using the efficient Glaser coupling reaction, the multiblock copolymer (PEO-b-PS-b-PEO-Diyne)s was synthesized and the dyine groups embedded in the main chain were modified by a thiol–yne reaction to give multiblock copolymer [PEO-b-PS-b-PEO-(OH)4]s. Also, using the efficient Williamson reaction, the multiblock copolymer (PEO-b-PS-b-PEO-Acetal)s was obtained. Finally, the micellar morphologies formed from the synthesized copolymers were investigated and compared by DLS and TEM measurements, and the in vivo distribution of the micelles was also studied by loading them with a fluorescent probe. The results revealed that, under the same conditions, the multiblock copolymers can form micelles of different sizes. Due to the hydrophobicity of the introduced dyine groups and PS segments, smaller sized micelles can be formed, which traverse the BBB and therefore might result in a therapeutic application in the treatment of brain disease. However, the hydrophilicity of the acetal and hydroxyl groups gave a similar effect to that of the PEO segment, and larger sized micelles were formed.
Co-reporter:Lingdi Chen, Jian Huang, Xuepu Wang, Chengjiao Lu, Hongdong Zhang and Guowei Wang
RSC Advances 2015 vol. 5(Issue 41) pp:32358-32368
Publication Date(Web):10 Mar 2015
DOI:10.1039/C4RA16580B
A series of novel dumbbell shaped copolymers poly(ethylene oxide)x-b-polystyrene-b-poly(ethylene oxide)x (PEOx-b-PS-b-PEOx, x = 1, 2, 3) composed of different numbers of hydrophilic PEO and hydrophobic PS segments were prepared by combination of living anionic polymerization (LAP) and ring opening polymerization (ROP) mechanisms, and the efficient thiol-ene addition reaction was also adopted. First, the functional polystyrene with one hydroxyl group and one allyl group at each end (AGE-PS-AGE) was synthesized by the LAP of St monomers followed by the capping reaction with allyl glycidyl ether (AGE). Subsequently, by thiol-ene addition reaction with 2-mercaptoethanol (ME) and 3-mercapto-1,2-propanediol (MP), one allyl group on the AGE-PS-AGE was transformed into one or two hydroxyl groups to synthesize the functional polystyrene with two hydroxyl groups at both ends (ME-PS-ME) or three hydroxyl groups at both ends (MP-PS-MP). Then, the copolymers PEOx-b-PS-b-PEOx were achieved by ROP of EO monomers using AGE-PS-AGE, ME-PS-ME and MP-PS-MP as macro-initiators. The target copolymers and their precursors were fully characterized by GPC, 1H NMR and 13C NMR measurements. The crystallization behavior of copolymers with different topologies and compositions was investigated by DSC, XRD and POM instruments, and the results showed that the topologies (compared to the compositions) tend to make the primary contribution to the crystallization behavior.
Co-reporter:Xiaoshan Fan, Zhiguo Hu and Guowei Wang
RSC Advances 2015 vol. 5(Issue 122) pp:100816-100823
Publication Date(Web):18 Nov 2015
DOI:10.1039/C5RA19942E
A novel type of amphiphilic copolymer POSS-(G3-PLLA-b-PEO-COOH)8 with a hydrophobic third-generation dendritic PLLA core and a functionalized hydrophilic PEO shell with surface carboxylic groups was synthesized as a carrier for drug delivery. The POSS-(G3-PLLA-OH)8 core was first synthesized by the combination of repetitive ring-opening polymerization (ROP) of L-lactide and branching reactions. Second, the amphiphilic copolymer POSS-(G3-PLLA-b-PEO-COOH)8 was obtained by esterification coupling between allyl-PEO-COOH chains and POSS-(G3-PLLA-OH)8, followed by the peripheral allyl groups reacting with 3-mercaptopropionic acid (MPA). In aqueous solution, this amphiphilic copolymer exists as stable unimolecular micelles with a unique core–shell structure and uniform size distribution (99.9–102.5 nm), as detected by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Doxorubicin (DOX), an anticancer drug, was encapsulated into POSS-(G3-PLLA-b-PEO-COOH)8 micelles to evaluate the drug release profile. The result showed that the DOX-loaded micelles, with a loading content 18.5 ± 2.3 w/w%, exhibited controlled release of up to 39% loaded drug over a time period of 80 h. In addition, the surface carboxylic groups provide the opportunity for further conjugating targeting molecules, fluorescence dye or even drugs. These results indicated that the structurally stable unimolecular micelles from POSS-(G3-PLLA-b-PEO-COOH)8 hold potential applications as controlled drug delivery nanocarriers.
Co-reporter:Jian Huang;Xuepu Wang
Polymer International 2015 Volume 64( Issue 9) pp:1202-1208
Publication Date(Web):
DOI:10.1002/pi.4891
Abstract
The AB type diblock PS-b-PEO and ABA type triblock PS-b-PEO-b-PS copolymers containing the same proportions of polystyrene (PS) and poly(ethylene oxide) (PEO) but different connection sequence were synthesized and investigated. Using the sequential living anionic polymerization and ring-opening polymerization mechanisms, diblock PS-b-PEO copolymers with one hydroxyl group at the PEO end were obtained. Then, using the classic and efficient Williamson reaction (realized in a ‘click’ style), triblock PS-b-PEO-b-PS copolymers were achieved by a coupling reaction between hydroxyl groups at the PEO end of PS-b-PEO. The PS-b-PEO and PS-b-PEO-b-PS copolymers were well characterized by 1H NMR spectra and SEC measurements. The critical micelle concentration (CMC) and thermal behaviors were also investigated by steady-state fluorescence spectra and DSC, respectively. The results showed that, because the PEO segment in triblock PS-b-PEO-b-PS was more restricted than that in diblock PS-b-PEO copolymer, the former PS-b-PEO-b-PS copolymer always gave higher CMC values and lower crystallization temperature (Tc), melting temperature (Tm) and degree of crystallinity (Xc) parameters. © 2015 Society of Chemical Industry
Co-reporter:Xiaoshan Fan;Zhiguo Hu
Journal of Polymer Science Part A: Polymer Chemistry 2015 Volume 53( Issue 15) pp:1762-1768
Publication Date(Web):
DOI:10.1002/pola.27618
ABSTRACT
This article reports on developing an efficient synthesis approach to aliphatic polyester dendrimer, poly(thioglycerol-2-propionate) (PTP), by combination of thio-bromo “Click” chemistry with atom transfer nitroxide radical coupling (ATNRC). Through the one-pot two-step method, linear polystyrene with hydroxyl end groups (l-PS-2OH) was obtained by first atom transfer radical polymerization of styrene and following termination using 4-(2,3-dihydroxypropoxy)-TEMPO (DHP-TEMPO) to capture the PS macroradicals via ATNRC method. Using l-PS-2OH as support, the dendritic repeating units divergently were grown from the hydroxyl end groups via esterification and thio-bromo “Click” reaction two-step process. In every generation, the resulting intermediates l-PS-d-PTP (G1-G4) can be easily isolated from the excessive unreacted monomers by simple precipitation in ethanol without help of time, labor and solvent consuming column chromatographic purification. At last, cleavage of the alkoxyamine group between the PS support and dendrimer at elevated temperature (125 °C) provided the targeted polyester dendrimer PTP up to the fourth generation. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1762–1768
Co-reporter:Jiaxing Zhang
Science China Chemistry 2015 Volume 58( Issue 11) pp:1674-1694
Publication Date(Web):2015 November
DOI:10.1007/s11426-015-5463-1
Because glycidyl (Gly) contains an epoxy and an active hydroxyl group, the Gly unit is difficult to introduce into certain polymeric chains in a controlled manner and usually yields hyperbranched polyglycidyl. Alternatively, the monomer 1-ethoxyethyl glycidyl ether (EEGE), derived from Gly and ethyl vinyl ether, has shown potential for application in polymer chemistry, and homopolymerization of this monomer directly produces linear poly(1-ethoxyethyl glycidyl ether) and further yields linear polyglycidyl. In this review, the initiation system of the EEGE monomer is first discussed in terms of chain transfer to monomers in ring-opening polymerization of epoxides with substituent groups. Then, random copolymerization of EEGE with other epoxides is considered. In addition, because the EEGE units on polymers can be transferred to Gly units and further used to construct copolymers with complicated architectures, the applications of EEGE monomers to block, graft, and hyperbranched copolymers are reviewed. Finally, the synthesis of main chain and terminal functional polyethers by transforming the hydroxyl groups at the polymer end or on the main chain into certain functional groups are also discussed. Chemistry based on EEGE has been proved to be an efficient, versatile route to constructing copolymers containing Gly units and ultimately yielding the target properties and applications.
Co-reporter:Guowei Wang and Junlian Huang
Polymer Chemistry 2014 vol. 5(Issue 2) pp:277-308
Publication Date(Web):29 Aug 2013
DOI:10.1039/C3PY00872J
The development of various polymerization mechanisms has paved the way for the construction of well-defined polymers with complicated structures. However, a single polymerization mechanism or a simple combination of several mechanisms often cannot meet the requirements. Thus, some efficient coupling reactions would play an important role in polymer science. In this review, we focused on the application of radical coupling in the construction of topological polymers. The atom transfer radical coupling (ATRC) reaction and agent (such as styrene, nitrone or diene) assisted radical coupling proceeded in a homocoupling style and polymers with symmetrical structures were obtained. As a more versatile method, nitroxide radical coupling (NRC) was also discussed, which proceeded in a heterocoupling style and polymers with various asymmetrical structures could be designed. Finally, the prospects of radical based coupling reactions in polymer science were also suggested.
Co-reporter:Chengjiao Lu, Lingdi Chen, Kun Huang and Guowei Wang
RSC Advances 2014 vol. 4(Issue 82) pp:43682-43690
Publication Date(Web):29 Aug 2014
DOI:10.1039/C4RA07084D
The amphiphilic triblock copolymers poly(acrylic acid)-b-poly(styrene)-b-poly(acrylic acid) (PAA-b-PS-b-PAA) and PS-b-PAA-b-PS with identical compositions but different block sequences were synthesized by a combination of an atom transfer radical polymerization (ATRP) mechanism and a nitroxide radical coupling (NRC) reaction or copper-catalyzed azide/alkyne click (CuAAC) chemistry. Firstly, the diblock copolymers TMS––PS-b-PtBA-Br were prepared by sequential ATRP of styrene (St) and tert-butyl acrylate (tBA) monomers from trimethylsilyl propargyl 2-bromoisobutyrate (TMS-PgBiB) initiator. Then, the triblock copolymers PS-b-PtBA-b-PS were prepared by NRC reaction between TMS––PS-b-PtBA-Br and coupling agent bis[4-(2,2,6,6-tetramethylpiperidine-1-oxyl)] succinate (Bis-TEMPO2). And the triblock copolymers PtBA-b-PS-b-PtBA were obtained by CuAAC chemistry between Alkynyl-PS-b-PtBA-Br and a coupling agent 1,4-diazidobutane (Di-Azide2). The target triblock copolymers PAA-b-PS-b-PAA and PS-b-PAA-b-PS were finally derived from the cleavage of the corresponding PS-b-PtBA-b-PS and PtBA-b-PS-b-PtBA. The self-assembly behaviour was preliminarily studied by FLS, FESEM and DLS instruments, and the results showed that the PS-b-PAA-b-PS and PAA-b-PS-b-PAA could give distinct critical micelle concentration (cmc) values and different sizes of micelles in water.
Co-reporter:Xuepu Wang, Jian Huang, Lingdi Chen, Yujie Liu, and Guowei Wang
Macromolecules 2014 Volume 47(Issue 22) pp:7812-7822
Publication Date(Web):November 12, 2014
DOI:10.1021/ma501613x
The thermal degradable poly(alkoxyamine) was synthesized through a novel nitroxide radical coupling step growth polymerization (NRC-SGP) mechanism. The monomers of 1,4-phenylene bis(2-bromo-2-methylpropanoate) (monomer 1) and 1,4-phenylene bis(2-bromopropanoate) (monomer 1′) with two bromide groups and 1,6-di(4-(2,2,6,6-tetramethylpiperidine-1-oxyl))-hexa-2,4-diyne (monomer 2) with two nitroxide radicals were first designed and synthesized. Then the NRC-SGP mechanism was investigated in detail by optimizing the factors such as polymerization time, temperature, solvents, catalysts, ligand, monomer concentration, and structures connected to halogen groups. The results showed that the termination by disproportionation was the major side reaction in the NRC-SGP mechanism, and the lower temperature (25 °C) would favor an important contribution. The proper combination of all factors could lead to an ideal NRC-SGP procedure. Finally, the thermal stability of formed poly(alkoxyamine) was monitored by TG, DSC and SEC instruments, and the results showed that the poly(alkoxyamine) would suffer a severe thermal degradation at the elevated temperature above 140 °C.
Co-reporter:Tingting Tang, Xiaoshan Fan, Ying Jin, Guowei Wang
Polymer 2014 Volume 55(Issue 16) pp:3680-3687
Publication Date(Web):5 August 2014
DOI:10.1016/j.polymer.2014.05.066
Series of graft copolymers with [Poly(epichlorohydrin-co-ethylene oxide)] [Poly(ECH-co-EO)] as backbone and polystyrene (PS), poly(isoprene) (PI) or their block copolymers as side chains were successfully synthesized by combination of ring-opening polymerization (ROP) with living anionic polymerization. The Poly(ECH-co-EO) with high molecular weight (Mn = 3.3 × 104 g/mol) and low polydispersity index (PDI = 1.34) was firstly synthesized by ring-ROP using ethylene glycol potassium as initiator and triisobutylaluminium (i-Bu3Al) as activator. Subsequently, by “grafting onto” strategy, the graft copolymers Poly(ECH-co-EO)-g-PI, Poly(ECH-co-EO)-g-PS and Poly(ECH-co-EO)-g-(PI-b-PS) were obtained using the coupling reaction between living PI−Li+, PS−Li+ or PS-b-PI−Li+ species capped with or without 1,1-diphenylethylene (DPE) agent and chloromethyl groups on poly(ECH-co-EO). By model experiment, the addition of DPE agent was confirmed to have an important effect on the grafting efficiency at room temperature. Finally, the target graft copolymers and intermediates were characterized by SEC, 1H NMR, MALLS and FTIR in detail, and thermal behaviours of the graft copolymers were also investigated by DSC measurement.
Co-reporter:Yingying Ma;Jian Huang;Kunyan Sui
Journal of Polymer Science Part A: Polymer Chemistry 2014 Volume 52( Issue 16) pp:2239-2247
Publication Date(Web):
DOI:10.1002/pola.27239
ABSTRACT
The graft polymer poly(ethylene oxide)-g-poly(ɛ-caprolactone)2 (PEO-g-PCL2) with modulated grafting sites was synthesized by the combination of ring-opening polymerization (ROP) mechanism, efficient Williamson reaction, with thiol–ene addition reaction. First, the precursor of PEO-Allyl-PEO with two terminal hydroxyl groups and one middle allyl group was prepared by ROP of EO monomers. Then, the macroinitiator [PEO-(OH)2-PEO]s was synthesized by sequential Williamson reaction between terminal hydroxyl groups and thiol–ene addition reaction on pendant allyl groups. Finally, the graft polymer PEO-g-PCL2 was obtained by ROP of ɛ-CL monomers using [PEO-(OH)2-PEO]s as macroinitiator. The target graft polymer and all intermediates were well characterized by the measurements of gel permeation chromatography, 1H NMR, and thermal gravimetric analysis. The crystallization behavior was investigated by the measurements of differential scanning calorimetry, wide-angle X-ray diffraction and polarized optical microscope. The results showed that when the PCL content of side chains reached 59.2%, the crystalline structure had been dominated by PCL part and the crystalline structure formed by PEO part can be almost neglected. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2239–2247
Co-reporter:Chenyan Liu, Kai Lv, Bing Huang, Chuanlin Hou and Guowei Wang
RSC Advances 2013 vol. 3(Issue 39) pp:17945-17953
Publication Date(Web):25 Jul 2013
DOI:10.1039/C3RA43024C
Using a “grafting from” strategy, the graft copolymer poly(ethylene oxide)-g-[poly(ethylene oxide)-b-poly(ε-caprolactone)] [PEO-g-(PEO-b-PCL)] with double crystallizable side chains was synthesized by a sequential ring-opening polymerization (ROP) mechanism. First, the ethoxyethyl glycidyl ether (EEGE) monomers containing a protected hydroxyl group were copolymerized with ethylene oxide (EO) monomers to form poly(ethylene oxide-co-ethoxyethyl glycidyl ether) [poly(EO-co-EEGE)], and the pendant hydroxyl groups were recovered by cleavage of the protecting groups for give poly(ethylene oxide-co-glycidyl) [poly(EO-co-Gly)]. Then, using poly(EO-co-Gly) with the pendant hydroxyl groups as a macroinitiator, the graft copolymer poly(ethylene oxide)-g-poly(ethylene oxide) (PEO-g-PEO) was obtained by ring-opening polymerization (ROP) of the EO monomers, and the graft copolymer PEO-g-(PEO-b-PCL) was obtained by sequential ROP of ε-CL monomers. The target PEO-g-(PEO-b-PCL) and intermediates were all characterized in detail by size-exclusion chromatography (SEC) and Proton Nuclear Magnetic Resonance Spectroscopy (1H NMR). The thermal stability and crystallization behaviors were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The results showed that the graft structure and compositions had important effects on the thermal stability and crystallization behaviors, and the crystallizability of graft copolymers was predominantly controlled by the outer segments.
Co-reporter:Qianqian Guo;Chenyan Liu;Tingting Tang;Jian Huang;Xinge Zhang
Journal of Polymer Science Part A: Polymer Chemistry 2013 Volume 51( Issue 21) pp:4572-4583
Publication Date(Web):
DOI:10.1002/pola.26874
ABSTRACT
Using core-first strategy, the amphiphilic A4B4 star-shaped copolymers [poly(ethylene oxide)]4[poly(ε-caprolactone)]4 [(PEO)4(PCL)4], [poly(ethylene oxide)]4[poly(styrene)]4 [(PEO)4(PS)4], and [poly(ethylene oxide)]4[poly(tert-butyl acrylate)]4 [(PEO)4(PtBA)4] were synthesized by mechanisms transformation combining with thiol-ene reaction. First, using a designed multifunctional mikto-initiator with four active hydroxyl groups and four allyl groups, the four-armed star-shaped polymers (PEO-Ph)4/(OH)4 with four active hydroxyl groups at core position were obtained by sequential ring-opening polymerization (ROP) of ethylene oxide monomers, capping reaction of living oxyanion with benzyl chloride, and transformation of allyl groups into hydroxyl groups by thiol-ene reaction. Then, the A4B4 star-shaped copolymers (PEO)4(PS)4 or (PEO)4(PtBA)4 were obtained by atom transfer radical polymerization (ATRP) of styrene or tert-butyl acrylate (tBA) monomers from macroinitiator of (PEO-Ph)4/(Br)4, which was obtained by esterification of (PEO-Ph)4/(OH)4 with 2-bromoisobutyryl bromide. The A4B4 star-shaped copolymers (PEO)4(PCL)4 were also obtained by ROP of ε-caprolactopne monomers from macroinitiator of (PEO-Ph)4/(OH)4. The target copolymers and intermediates were characterized by size-exclusion chromatography, matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy, and nuclear magnetic resonance in detail. This synthetic route might be a versatile one to various AnBn (n ≥ 3) star-shaped copolymers with defined structure and compositions. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4572–4583
Co-reporter:Tingting Tang;Jian Huang;Bing Huang;Junlian Huang
Journal of Polymer Science Part A: Polymer Chemistry 2012 Volume 50( Issue 24) pp:5144-5150
Publication Date(Web):
DOI:10.1002/pola.26348
Abstract
The graft polymers [poly(isoprene)-graft-poly(styrene)] (PI-g-PS), [poly(isoprene)-graft-poly(isoprene)] (PI-g-PI), [poly(isoprene)-graft-(poly(isoprene)-block-poly(styrene))] PI-g-(PI-b-PS), and [poly(isoprene)-graft-(poly(styrene)-block-poly(isoprene))] PI-g-(PS-b-PI) with PI as main chain were synthesized through living anionic polymerization (LAP) mechanism and the efficient coupling reaction. First, the PI was synthesized by LAP mechanism and epoxidized in H2O2/HCOOH system for epoxidized PI (EPI). Then, the graft polymers with controlled molecular weight of main chain and side chains, and grafting ratios were obtained by coupling reaction between PI−Li+, PS−Li+, PS-b-PI−Li+, or PI-b-PS−Li+ macroanions and the epoxide on EPI. The target polymers and all intermediates were well characterized by SEC,1H NMR, as well as their thermal properties were also evaluated by DSC. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Co-reporter:Guowei Wang;Bin Hu;Xiaoshan Fan;Yannan Zhang ;Junlian Huang
Journal of Polymer Science Part A: Polymer Chemistry 2012 Volume 50( Issue 11) pp:2227-2235
Publication Date(Web):
DOI:10.1002/pola.25996
Abstract
The tadpole-shaped copolymers polystyrene (PS)-b-[cyclic poly(ethylene oxide) (PEO)] [PS-b-(c-PEO)] contained linear tail chains of PS and cyclic head chains of PEO were synthesized by combination of Glaser coupling with living anionic polymerization (LAP) and ring-opening polymerization (ROP). First, the functionalized polystyrene-glycerol (PS-Gly) with two active hydroxyl groups at ω end was synthesized by LAP of St and the subsequent capping with 1-ethoxyethyl glycidyl ether and then deprotection of protected hydroxyl group in acid condition. Then, using PS-Gly as macroinitiator, the ROP of EO was performed using diphenylmethylpotassium as cocatalyst for AB2 star-shaped copolymers PS-b-(PEO-OH)2, and the alkyne group was introduced onto PEO arm end for PS-b-(PEO-Alkyne)2. Finally, the intramolecular cyclization was performed by Glaser coupling reaction in pyridine/Cu(I)Br/N,N,N′,N″,N″-pentamethyldiethylenetriamine system under room temperature, and tadpole-shaped PS-b-(c-PEO) was formed. The target copolymers and their intermediates were well characterized by size-exclusion chromatography, proton nuclear magnetic resonance spectroscopy, and fourier transform infrared spectroscopy in details. The thermal properties was also determined and compared to investigate the influence of architecture on properties. The results showed that tadpole-shaped copolymers had lower Tm,Tc, and Xc than that of their precursors of AB2 star-shaped copolymers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Co-reporter:Kun Huang;Jian Huang;Mugang Pan;Junlian Huang
Journal of Polymer Science Part A: Polymer Chemistry 2012 Volume 50( Issue 13) pp:2635-2640
Publication Date(Web):
DOI:10.1002/pola.26037
Abstract
The amphiphilic A2B star-shaped copolymers of polystyrene-b-[poly(ethylene oxide)]2 (PS-b-PEO2) were synthesized via the combination of atom transfer nitroxide radical coupling (ATNRC) with ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP) mechanisms. First, a novel V-shaped 2,2,6,6-tetramethylpiperidine-1-oxyl-PEO2 (TEMPO-PEO2) with a TEMPO group at middle chain was obtained by ROP of ethylene oxdie monomers using 4-(2,3-dihydroxypropoxy)-TEMPO and diphenylmethyl potassium as coinitiator. Then, the linear PS with a bromine end group (PS-Br) was obtained by ATRP of styrene monomers using ethyl 2-bromoisobutyrate as initiator. Finally, the copolymers of PS-b-PEO2 were obtained by ATNRC between the TEMPO and bromide groups on TEMPO-PEO2 and PS-Br, respectively. The structures of target copolymers and their precursors were all well-defined by gel permeation chromatographic and nuclear magnetic resonance (1H NMR). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Co-reporter:Xiaoshan Fan;Tingting Tang;Kun Huang;Junlian Huang
Journal of Polymer Science Part A: Polymer Chemistry 2012 Volume 50( Issue 15) pp:3095-3103
Publication Date(Web):
DOI:10.1002/pola.26096
Abstract
A novel amphiphilic branch-ring-branch tadpole-shaped [linear-poly(ε-caprolactone)]-b-[cyclic-poly(ethylene oxide)]-b-[linear-poly(ε-caprolactone)] [(l-PCL)-b-(c-PEO)-b-(l-PCL)] was synthesized by combination of glaser coupling reaction with ring-opening polymerization (ROP) mechanism. The self-assembling behaviors of (l-PCL)-b-(c-PEO)-b-(l-PCL) and their π-shaped analogs of poly(ε-caprolactone)/poly(ethylene oxide)]-b-poly(ethylene oxide)-b-[poly(ε-caprolactone)/poly(ethylene oxide) with comparable molecular weight in water were preliminarily investigated. The results showed that the micelles formed from the former took a fiber look, however, that formed from the latter took a spherical look. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Co-reporter:Xiaoshan Fan, Bing Huang, Guowei Wang, Junlian Huang
Polymer 2012 Volume 53(Issue 14) pp:2890-2896
Publication Date(Web):21 June 2012
DOI:10.1016/j.polymer.2012.04.023
The biocompatible tadpole-shaped copolymers [cyclic-poly(ethylene oxide) (PEO)]-b-[linear poly(ɛ-caprolactone) (PCL)]2 [(c-PEO)-b-PCL2] with one PEO ring and two PCL tails were synthesized by combination of glaser coupling with ring-opening polymerization (ROP). First, a linear PEO precursor with two alkyne groups at the chain terminal and two hydroxyl groups at the chain middle was prepared by ROP of EO monomer and the following transformation of functional groups. Then, cyclic PEO with two hydroxyl groups at the same site was obtained by the “Glaser” cyclization. Finally, the hydroxyl groups on cyclic PEO directly initiated the ROP of ɛ-CL monomer to produce the target copolymers (c-PEO)-b-PCL2. The target copolymers and intermediates were all well characterized by GPC, MALDI-TOF MS, 1H NMR and FT-IR.
Co-reporter:Bing Huang;Xiaoshan Fan;Yannan Zhang ;Junlian Huang
Journal of Polymer Science Part A: Polymer Chemistry 2012 Volume 50( Issue 12) pp:2444-2451
Publication Date(Web):
DOI:10.1002/pola.26021
Abstract
The twin-tail tadpole-shaped (cyclic polystyrene)-block-[linear poly (tert-butyl acrylate)]2 [(c-PS)-b-(l-PtBA)2] was synthesized by combination of Glaser coupling reaction with atom transfer radical polymerization (ATRP) and living anionic polymerization (LAP). First, the telechelic PS with an active and an ethoxyethyl-protected hydroxyl groups at both ends was prepared by LAP of St monomers using lithium naphthalenide as initiator and terminated by 1-ethoxyethyl glycidyl ether. And the alkyne groups were introduced onto each PS end by selectively reaction of active hydroxy group with propargyl bromide in NaH/tetrahydrofuran (THF) system. Then, the intramolecular cyclization was carried out by Glaser coupling reaction in pyridine/Cu(I)Br system in air atmosphere. Finally, the macroinitiator of c-PS with two bromine groups at the junction point was synthesized via the cleavage of ethoxyethyl group and the subsequent esterification of the deprotected hydroxyl groups with 2-bromoisobutyryl bromide. The copolymer of (c-PS)-b-(l-PtBA)2 was obtained by ATRP of tBA monomers, and the PtBA segment was also hydrolyzed for (cyclic polystyrene)-block-(linear polyacrylic acid)2 [(c-PS)-b-(l-PAA)2]. The target copolymers and all intermediates were well characterized by GPC, MALDI-TOF MS, and 1H NMR in detail. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Co-reporter:Xiaoshan Fan, Bing Huang, Guowei Wang, and Junlian Huang
Macromolecules 2012 Volume 45(Issue 9) pp:3779-3786
Publication Date(Web):April 26, 2012
DOI:10.1021/ma300487x
An amphiphilic heteroeight-shaped polymer cyclic-[poly(ethylene oxide)-b-polystyrene]2 ([c-(PEO-b-PS)]2) composed of hydrophilic PEO and hydrophobic PS blocks was synthesized by combination of “click” chemistry with anionic ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP) mechanisms. According to “core-first” strategy, the A2B2 star-shaped precursor (PEO-alkyne)2-(PS-N3)2 was obtained by successive ROP of EO monomer, ATRP of St monomer, and modification of functional groups. Under high dilution condition, the intramolecular cyclization of (PEO-alkyne)2-(PS-N3)2 by “click” chemistry produced the amphiphilic heteroeight-shaped polymer [c-(PEO-b-PS)]2. The target copolymers and intermediates were well characterized by GPC, MALDI-TOF MS, 1H NMR, and FT-IR. The self-assembly behavior of [c-(PEO-b-PS)]2 and its precursor of (PEO-alkyne)2-(PS-N3)2 were investigated and compared by transmission electron microscopy (TEM) and dynamic light scattering (DLS). In both cases, the spherical micelles were observed, however, the size of formed micelles increased from a star-shaped to a cyclic topology.
![2H-Isoindol-2-yloxy, 5-[[4-(1-bromoethyl)benzoyl]oxy]-1,3-dihydro-1,1,3,3-tetramethyl-](/data/chemimg/3781800/1872202-98-6.png)
![2H-Isoindol-2-yloxy, 5-[[4-(1-bromoethyl)benzoyl]oxy]-1,3-dihydro-1,1,3,3-tetramethyl-](/data/chemimg/3781800/1872202-98-6_b.png)
![1-Piperidinyloxy, 2,2,6,6-tetramethyl-4-[(2-propyn-1-yloxy)carbonyl]-](/data/chemimg/3781800/912328-46-2.png)
![1-Piperidinyloxy, 2,2,6,6-tetramethyl-4-[(2-propyn-1-yloxy)carbonyl]-](/data/chemimg/3781800/912328-46-2_b.png)
![Nitroxide, 1-[4-(2-bromo-1-oxopropoxy)phenyl]-1,2-dimethylpropyl 1,1-dimethylethyl](/data/chemimg/3781800/1872202-95-3.png)
![Nitroxide, 1-[4-(2-bromo-1-oxopropoxy)phenyl]-1,2-dimethylpropyl 1,1-dimethylethyl](/data/chemimg/3781800/1872202-95-3_b.png)
