Co-reporter:Guang-Xin Chen;Wenjing Zhang;Qifang Li;Zheng Zhou
Industrial & Engineering Chemistry Research April 23, 2014 Volume 53(Issue 16) pp:6699-6707
Publication Date(Web):Publication Date (Web): March 27, 2014
DOI:10.1021/ie404204g
A synthetic strategy of coating multiwalled carbon nanotubes (MWCNTs) with cross-linkable octa-acrylate polyhedral oligomeric silsesquioxane (POSS) by combining Diels–Alder cycloadditions with atom transfer radical polymerization in a controlled manner is reported. First, the furfuryl-2-bromoisobutyrate is synthesized by an esterification reaction from 2-bromoisobutyryl bromide and furfuryl alcohol. Then, the MWCNT-based initiators of atom transfer radical polymerization (ATRP) are synthesized through a Diels–Alder reaction between MWCNTs and furfuryl-2-bromoisobutyrate with controlled grafted content. The MWCNT initiators are used to initiate the ATRP reaction of the octa-acrylate POSS on the MWCNT surface. Finally, a core–shell structure with a MWCNT at the center is obtained, with the thickness of the POSS shell adjusted through different initiators from 5, 10, to 15 nm. The POSS-coated MWCNT is compounded with polyvinylidene fluoride to obtain a kind of composite which has both high dielectric permittivity and low dielectric loss.
Co-reporter:Lei Zhu, Chao Jiang, Guangxin Chen, Zheng Zhou, Qifang Li
Organic Electronics 2017 Volume 49(Volume 49) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.orgel.2017.06.035
•Understanding the influence of side chain length or structure on the properties of isoindigo based conjugated polymers.•The alkyl side chains on isoindigo unit have no effect on the optical properties of individual molecules.•Alkyl side chains have a significant impact on a series properties of the polymers in the aggregated state.•Hexyl-decyl substituted isoindigo based polymer has the best performance.A series of donor-acceptor (D-A) conjugated polymers based on benzo[1,2-b:4,5-b’]dithiophene (BDT) and isoindigo with different alkyl side chains were designed and synthesized. These polymers named PBDT-TT-IIDO, PBDT-TT-IIDEH, PBDT-TT-IIDBO, PBDT-TT-IIDHD, and PBDT-TT-IIDOD have different length or structure of the alkyl side chains on isoindigo unit. As the length of the alkyl chain increases, the solubility of the polymer enhances. The results indicate that the alkyl side chains have little effect on the optical properties of individual polymer molecules, but have a significant impact on optical, electrochemical, film-forming and photovoltaic properties of the polymers in the aggregated state. PBDT-TT-IIDHD with a sixteen carbon branched chain achieves the best power conversion efficiencies (PCEs) of 6.83% when blending with [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) as acceptor. The influence of the alkyl side chain on the short-circuit current is much greater than that of the open circuit voltage. Atomic force microscopy (AFM) reveals that the side chains changed the morphology of the active layers and the size of the phase region. For isoindigo based polymers, hexyl-decyl group in the commonly used alkyl chains appear to be a good choice.Understanding the influence of side chain length and structure on the properties of isoindigo based conjugated polymers.Download high-res image (182KB)Download full-size image
Co-reporter:Han Pan;Zuo Xiao;Fangyuan Xie;Qifang Li;Liming Ding
RSC Advances (2011-Present) 2017 vol. 7(Issue 6) pp:3439-3442
Publication Date(Web):2017/01/04
DOI:10.1039/C6RA27292D
An aromatic lactam acceptor unit, [2,2′-bidithieno[3,2-b:2′,3′-d]pyridine]-5,5′(4H,4′H)-dione (BDTPi), was developed for making D–A copolymer donors. Two D–A copolymers, PThBDTPi and PSeBDTPi, gave power conversion efficiencies (PCEs) of 8.11% and 6.50%, respectively, when using PC71BM as the acceptor.
Co-reporter:Guangzhong Yin, Donglin Zhao, Ye Ren, Lianwei Zhang, Zheng Zhou and Qifang Li
Biomaterials Science 2016 vol. 4(Issue 2) pp:310-318
Publication Date(Web):16 Nov 2015
DOI:10.1039/C5BM00414D
PLLA porous materials with high porosity were prepared by a gradual precipitation method and further modified by using different concentrations of gelatin aqueous solutions. Therefore, porous materials with different contents of gelatin coating were obtained. The micro morphology, crystallization, thermal performance, hydrophilicity and mechanical properties of the materials were evaluated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), thermogravimetric analysis (TGA), water uptake ability tests and compression tests. It was found that the modified materials were formed by the stacking of nanosheets. The materials can maintain more than 80% porosity, high water uptake abilities and fast water uptake rates after modification. The compressive moduli of the materials were significantly improved from the initial sample with a value of 0.57 MPa to 46.41 MPa with gelatin modification. Due to the high porosity of materials, interconnected pore structures, and good surface hydrophilicity, the materials were expected to be widely used in the field of tissue engineering scaffolds, especially for bone substitutes, mainly due to their tunable and excellent mechanical properties.
Co-reporter:Min Wang, Manxi Zhou, Lei Zhu, Qifang Li, Chao Jiang
Solar Energy 2016 Volume 129() pp:175-183
Publication Date(Web):May 2016
DOI:10.1016/j.solener.2016.02.003
•Surface modification of PEDOT: PSS with DMSO in polymer solar cells.•Lateral electrical conduction effect in DMSO-treated solar cells.•Lowered resistance of the solar cell leads to increased efficiency of 6.52%.Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) films were post-treated with polar solvent dimethylsulfoxide (DMSO) by spin-coating method and polymer solar cells (PSCs) based on poly [N-9″]-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole) (PCDTBT) : [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) were fabricated to investigate the effect of the treatment. By post-modifying the PEDOT: PSS layer, the conductivity of the PEDOT: PSS film was largely improved. Using electrochemical impedance spectroscopy (IS) we observed that the series resistance of the device decreased greatly after the treatment. With DMSO-treated PEDOT: PSS transport layer, the power conversion efficiency (PCE) of the PSC based on PCDTBT: PC71BM raised from 5.95% to 6.52% with both increase in Jsc and FF. We systematically studied charge transport property via space-charge-limited-current (SCLC) and our results suggest that the increment in device efficiency can be attributed to the increased hole-mobility and thus more balanced charge transport benefits the enhancement of polymer solar cell efficiency. We also noted that if measured without a shadow mask much more overestimation will take place in the DMSO-treated device as a result of lateral electrical conduction. We suggest that when we apply the highly conductive PEDOT: PSS layer in the PSCs, careful measurement should be carried out to avoid inaccuracy.
Co-reporter:Ye Ren, Zheng Zhou, Guangzhong Yin, Guang-Xin Chen and Qifang Li
RSC Advances 2016 vol. 6(Issue 37) pp:31351-31358
Publication Date(Web):21 Mar 2016
DOI:10.1039/C6RA01675H
Supramolecular chemistry is a reliable and effective field that encompasses the functionalization of carbon nanotubes (CNTs) through non-covalent interactions, such as π–π stacking and cation–π interactions. In this work, poly(ε-caprolactone) (PCL) containing an ionic liquid group was synthesized through ring-opening polymerization of ε-caprolactone by using a hydroxylated ionic liquid derived from imidazole and 2-bromoethanol. Ionic liquid-containing PCL exhibited affinity for the π-conjugated structure in CNTs. The fabricated PCL/CNTs composite showed improved CNTs dispersion because of the addition of ionic liquid-containing PCL as a compatibilizer. The composites also demonstrated enhanced electronic and dielectric properties as a result of the excellent interfacial control by the compatibilizer, which could be due to the anchoring of PCL chains onto the CNTs surface via non-covalent (supramolecular) functionalization. This simple approach provides novel supramolecular tools for using renewable resources to prepare CNTs-based composites with high performance.
Co-reporter:Guangzhong Yin;Donglin Zhao;Lianwei Zhang;Jianyu Feng;Ye Ren;Guangxin Chen;Zheng Zhou;Qifang Li
Macromolecular Materials and Engineering 2016 Volume 301( Issue 3) pp:274-278
Publication Date(Web):
DOI:10.1002/mame.201500324
Co-reporter:Yaotian Su, Ye Ren, Guang-Xin Chen and Qifang Li
RSC Advances 2016 vol. 6(Issue 59) pp:53867-53872
Publication Date(Web):17 May 2016
DOI:10.1039/C6RA07945H
A core–shell microstructured hybrid was controllably synthesized by coating cross-linked polymer shell onto multiwalled carbon nanotubes (MWCNTs) via direct in situ free-radical polymerization, and was compounded with epoxy to solve the conundrum of percolative composites, namely large dielectric loss caused by direct contact between conductive fillers near the percolation threshold. The shell thickness of the prepared polymer-coated MWCNTs could be varied from 10 to 60 nm by controlling the weight ratio of the monomers. Because the insulative polymer shells serve as electrical barriers between the MWCNTs cores to form a continuous MWCNT-barrier network, the direct contact between the conductive fillers in the composites near the percolation threshold, that is to say the high leakage currents, can be effectively relieved. When the content of the coated MWCNTs reached 10 wt%, the dielectric properties of the composites achieved a dielectric constant value as high as 173.3 and a dielectric loss value as low as 0.021 at 105 Hz. The effect of the thickness of the coating layer on the dielectric properties of the composites was also investigated. This simple method of coating MWCNTs is expected to be applied to materials with a high dielectric constant and low dielectric loss in the field of microelectronics.
Co-reporter:Guangzhong Yin, Lianwei Zhang, Qifang Li
Materials Letters 2016 Volume 181() pp:208-211
Publication Date(Web):15 October 2016
DOI:10.1016/j.matlet.2016.05.167
•We prepare crosslinked PCL membranes by using dual pore-forming agents.•The method can be used to conveniently prepare the membrane with different porosity, pore size and thickness.•The membranes have application prospects in anti-adhesion barrier aspects.We report here a simple but practical method to prepare crosslinked PCL membranes by using dual pore-forming agents. Their porosities, section morphologies, melting behaviors and mechanical properties are evaluated. The results show that the membranes have a pore size close to 5 µm, and the porosities are maintained 70–80%. The mechanical properties show the membranes have improved Young's modules compared to the membranes obtained by some other methods. Notably, the second pore-forming agent, PEG, improves interconnectivity as well as surface roughness and makes the membrane thickness controllable conveniently.
Co-reporter:Ye Ren, Zheng Zhou, Guangzhong Yin, Guang-Xin Chen, Qifang Li
Materials Letters 2016 Volume 166() pp:133-136
Publication Date(Web):1 March 2016
DOI:10.1016/j.matlet.2015.12.052
•We report a method to prepare core–shell hybrids based on PIL-coated CNTs.•A thick PIL shell on CNTs surface was obtained by introducing divinylbenzene.•The PIL shell on CNTs can be adjusted from about 15 nm to 50 nm.•The dielectric property of hybrids was controlled with varied shell thicknesses.Functionalization of multi-walled carbon nanotubes (MWCNTs) with ionic liquids (IL) is an efficient method to improve the dispersibility and reactivity of MWCNTs. This work introduces a promising method for fabricating core–shell-structured MWCNTs–IL hybrids by using vinyl-benzyl IL as monomer for in situ controlled free-radical polymerization. Active radicals attached on the MWCNTs surface initiate the copolymerization of divinyl monomer and polymerizable IL. A polymer layer containing ionic species is formed and coated on the outer surface of MWCNTs. The resulting well-defined material shows excellent dielectric properties with different coating layer thicknesses.
Co-reporter:Min Wang, Lei Zhu, Manxi Zhou, Chao Jiang, Qifang Li
Materials Letters 2016 Volume 166() pp:227-230
Publication Date(Web):1 March 2016
DOI:10.1016/j.matlet.2015.12.088
•A new system of co-additives of DPE and DMSO was developed.•The effect of the co-additives was systematically investigated.•The highest PCE of PCDTBT:PC71BM based solar cells reached 7.13% by using the co-additives.Two high boiling point solvents namely diphenylether (DPE) and dimethylsulfoxide (DMSO) were employed as co-additives in fabricating poly [N-9″]-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3-benzothiadiazole) (PCDTBT): [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) based polymer solar cells (PSCs). It was found that the power conversion efficiency (PCE) can be improved to 7.13% for the PSCs processed with co-additives in comparison with ~6.5% for the PSCs processed with either DPE or DMSO additives. The enhanced PCE is benefited from simultaneous increase in Voc, Jsc and FF due to the co-additives fabricating process and the two additives are found to improve the photovoltaic performance with different mechanisms.
Co-reporter:Guangzhong Yin;Lianwei Zhang;Zheng Zhou;Qifang Li
Journal of Polymer Research 2016 Volume 23( Issue 11) pp:
Publication Date(Web):2016/11/01
DOI:10.1007/s10965-016-1044-z
Co-reporter:Guangzhong Yin;Lianwei Zhang;Qifang Li
Journal of Polymer Research 2016 Volume 23( Issue 7) pp:
Publication Date(Web):2016 July
DOI:10.1007/s10965-016-1028-z
PCL based hybrid films exhibiting heat-responsive shape memory properties had been obtained by using Heptaphenyltricycloheptasiloxane Trihydroxy Silanol (T7-OH) as a cross-linker. The crystallization behaviors of the materials were studied in detail by DSC and XRD. The thermal properties of the materials were detected through TGA. The static mechanical properties, in vitro degradation and shape memory properties were also studied systematically. There was no remarkable T7-OH crystal plane diffraction peak according to XRD which indicated that T7-OH was well dispersed in the matrix. Meanwhile, according to the TGA, thermal degradation temperatures were increased significantly when T7-OH were added. It was worth noting that the materials possessed excellent shape memory properties with Rf > 97 % and Rr > 97 %.
Co-reporter:Jinze Li, Li Ma, Guangxin Chen, Zheng Zhou and Qifang Li
Journal of Materials Chemistry A 2015 vol. 3(Issue 42) pp:8401-8409
Publication Date(Web):17 Sep 2015
DOI:10.1039/C5TB01702E
Stimuli-responsive hydrogels are soft, biocompatible and smart biomaterials; however, the poor mechanical properties of the hydrogels limit their application. Herein, we prepared a reductant- and light-responsive polyurethane hydrogel which was made of polyethylene glycol, 1,6-diisocyanatohexane, azobenzene, cyclodextrin and disulfide. Attenuated Total Reflectance Infrared Spectra and 1H NMR were used to characterize the structure of the hydrogel. The hydrogel has a high elasticity (a tensile modulus of 36.5 ± 0.5 kPa and a storage modulus of 52.9 ± 1.2 kPa) at a high water content (91.2 ± 0.4%). Swelling, mechanical and rheological properties of the hydrogel can be tuned by the content of the crosslinker, light and reductant. The hydrogel has low cytotoxicity and it can be used for drug delivery. Ultraviolet irradiation helped to load drugs and the reductant accelerated the drug release. With its high mechanical properties and light- and reductant-responsiveness, the hydrogel is hopefully to be used as a drug carrier.
Co-reporter:Manxi Zhou;Min Wang;Lei Zhu;Zhenqing Yang;Chao Jiang;Dapeng Cao;Qifang Li
Macromolecular Rapid Communications 2015 Volume 36( Issue 24) pp:2156-2161
Publication Date(Web):
DOI:10.1002/marc.201500466
Co-reporter:Guangzhong Yin, Donglin Zhao, Xiao Wang, Ye Ren, Lianwei Zhang, Xingxin Wu, Shaoping Nie and Qifang Li
RSC Advances 2015 vol. 5(Issue 96) pp:79070-79080
Publication Date(Web):08 Sep 2015
DOI:10.1039/C5RA15531B
Multi-block copolymer poly(ester-urethane)s with ethoxy or polyhedral oligomeric silsesquioxane (POSS) terminal functional groups were designed and synthesized by using polyethylene glycol–poly(ε-caprolactone)–poly(L-lactide) (PEG–PCL–PLLA) diols via urethane linkages. In addition, an efficient and green catalyst, bismuth ethylhexanoate, was used to prepare high molecular weight copolymers, and the influences of molecular compositions on the crystallinity, mechanical properties, biodegradability, cytocompatibility and blood-compatibility were systematically studied. By varying the terminal functional groups, as well as PEG, PCL and PLLA segment ratios, the materials exhibited highly tunable properties, especially including crystallinity, mechanical properties and degradation rate. Notably, these new functional materials may effectively be applied in the treatment of blood vessels because of the mentioned tunable properties.
Co-reporter:Shasha Li, Guangxin Chen, Zheng Zhou and Qifang Li
RSC Advances 2015 vol. 5(Issue 81) pp:65847-65855
Publication Date(Web):24 Jul 2015
DOI:10.1039/C5RA07158E
A novel thermo- and light-responsive random copolymer poly(o-nitrobenzyl methacrylate)-co-2-(2-methoxyethoxy)ethyl methacrylate-co-oligo(ethylene glycol)methacrylate (P(NBMA-co-MEO2MA-co-OEGMA)) was synthesized by atom transfer radical polymerization (ATRP). This amphiphilic random copolymer self-assembled into spherical micelles with a PNBMA core and a PMEO2MA/POEGMA corona in aqueous solution. Aggregates were formed when the temperature increased above the lower critical temperature (LCST). Upon UV irradiation, the transformation of hydrophobic PNBMA into hydrophilic poly(methacrylic acid) (PMAA) induced the disruption of the initial micelles and the release of the encapsulated fluorescent dye, Nile Red, into water. The accordingly obtained hydrophilic random copolymer P(MAA-co-MEO2MA-co-OEGMA) exhibited thermo- and pH-responsive behavior. Further increasing the temperature or decreasing the pH, P(MAA-co-MEO2MA-co-OEGMA) formed PMEO2MA/POEGMA-core or PMAA-core micelles with the re-encapsulation of Nile Red. This random copolymer has great potential in applications such as controlled release and selective encapsulation.
Co-reporter:Guangzhong Yin, Guangxin Chen, Zheng Zhou and Qifang Li
RSC Advances 2015 vol. 5(Issue 42) pp:33356-33363
Publication Date(Web):23 Mar 2015
DOI:10.1039/C5RA01971K
Alkyne-functionalized polyhedral oligomeric silsesquioxane was successfully prepared using the commercially available propargylic acid precursor through DCC coupling, and it was further used to modify PEG-b-PCL via click chemistry, resulting in a successful synthesis of POSS grafted PEG-b-PCL block copolymer. The structures of the samples were comprehensively confirmed by FTIR, 1H NMR, GPC and electrospray ionization mass spectrometry (ESI-MS). The thermal properties of the polymers were investigated via DSC. The copolymers with grafted POSS showed excellent thermal properties with an increase of approximately 100 °C in melting temperature compared with the neat PEG-b-PCL. Furthermore, the side group POSS with high crystallinity inducing ability acted as a physical crosslinking point and a thermal enhancement agent and effectively induced the ordered phase separation, giving rise to nanostructures with high parallelism and a smooth interface.
Co-reporter:Guang-Xin Chen;Shicheng Zhang;Zheng Zhou;Qifang Li
Polymer Composites 2015 Volume 36( Issue 1) pp:94-101
Publication Date(Web):
DOI:10.1002/pc.22917
“Bucky gels” of carbon nanotubes were successfully prepared by grinding multi-walled carbon nanotubes (MWNTs) and ionic liquids (ILs) for several hours. A series of poly(vinylidene fluoride) (PVDF) composites with Bucky gels was obtained through simple melt compounding. The Raman spectrum showed significant interaction among the ILs, MWNTs, and PVDF. The dielectric behavior of the PVDF composites based on unmodified and IL-modified MWNTs was studied from 40 Hz to 30 MHz. The addition of ILs significantly enhanced the dielectric property of the PVDF/IL/MWNT ternary composites, which was much higher than that of the sum of PVDF/IL and PVDF/MWNT binary composites. The SEM results revealed that both MWNTs and ILs uniformly dispersed throughout the PVDF/IL/MWNT composites because of the strong interaction between them. The DSC and XRD results showed that the addition of ILs in the composites changed the crystallinity and crystal form of the PVDF. POLYM. COMPOS., 36:94–101, 2015. © 2014 Society of Plastics Engineers
Co-reporter:Shasha Li;Sha Ji;Zheng Zhou;Guangxin Chen;Qifang Li
Macromolecular Chemistry and Physics 2015 Volume 216( Issue 11) pp:1192-1200
Publication Date(Web):
DOI:10.1002/macp.201500044
Co-reporter:Da Sun, Zheng Zhou, Guang-Xin Chen, and Qifang Li
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 21) pp:18635
Publication Date(Web):October 22, 2014
DOI:10.1021/am503633t
We report a synthetic strategy for coating multiwalled carbon nanotubes (MWCNTs) with cross-linked octa-methacrylate-polyhedral oligomeric silsesquioxane (MA-POSS) by direct, in situ free-radical polymerization in a controlled manner. This strategy resulted in a core–shell structure with an MWCNT center. The shell thickness could be varied from ∼7 nm to 40 nm by choosing different initiators, solvents, and weight ratios of MWCNT and octa-MA-POSS. Coated MWCNT hybrids had controlled electrical performance depending on the coating layer thickness and were well-dispersed in the polymer matrix. POSS-coated MWCNTs were compounded with poly(vinylidene fluoride) to obtain a composite with high dielectric permittivity and low dielectric loss.Keywords: carbon nanotubes; composites; dielectric loss; free-radical polymerization
Co-reporter:Xiang Li, Qifang Li, Guang-Xin Chen
Materials Letters 2014 Volume 134() pp:38-41
Publication Date(Web):1 November 2014
DOI:10.1016/j.matlet.2014.07.049
•We report a promoting process for traditional dip-coated boron nitride (BN) on CNT.•A thick BN shell coated on CNT was obtained by introducing alkali metal surfactant.•The BN shell on CNT can be adjusted from about 10 nm to 25 nm.•The electrical performance of hybrids was controlled with varied shell thicknesses.In this paper, we introduced sodium dodecyl benzene sulfonate (SDBS) to the impregnation solution to promote boron nitride (BN) formation on multi-walled carbon nanotubes (MWNTs) by dip-coating. BN coating formation on MWNTs can be greatly improved by SDBS. The resultant BN-coated MWNTs showed increased BN shell thickness, enhanced MWNT dispersion in the impregnation solution, and lower formation temperatures and times (at 1000 °C for 2 h under flowing nitrogen). The shell thickness of the MWNTs may be adjusted from about 10 nm to 25 nm. Electrical property testing also showed that increasing the shell thickness induces higher resistivity (from 0.12 Ω cm to 430 Ω cm) in the MWNTs.
Co-reporter:Dan Bi;Da Sun;Jiali Qu;Zheng Zhou;Qifang Li ;Guang-Xin Chen
Polymer Engineering & Science 2014 Volume 54( Issue 11) pp:
Publication Date(Web):
DOI:10.1002/pen.23793
Three kinds of novel organic montmorillonites (OMMTs) were prepared by reacting the amino polyhedral oligomeric silsesquioxanes (POSSs) with the OMMTs that had already been modified by cationic surfactants. The layer spacing of OMMT increased from 1.68 to 3.81 nm after being intercalated by POSS. Poly(l-lactide) (PLLA) based nanocomposites with montmorillonites were produced by melt compounding. The PLLA nanocomposites with POSS modified OMMT were comprised of a random dispersion of intercalated/exfoliated aggregates of layered silicates throughout the PLLA matrix. The incorporation of POSS modified OMMT resulted in a significant increase in both crystallization temperature and decomposition temperature for 5% weight loss in comparison with the virgin PLLA. Gas Permeation Analysis showed that the increase of the montmorillonite concentration in the polymer matrix led to an expected decrease in permeation values. Gas barrier properties of the nanocomposites were compared with those predicted by phenomenological models such as the Nielsen model and Cussler model. POLYM. ENG. SCI., 54:2489–2496, 2014. © 2013 Society of Plastics Engineers
Co-reporter:Tianfu Zhang, Jinze Wang, Manxi Zhou, Li Ma, Guangzhong Yin, Guangxin Chen, Qifang Li
Tetrahedron 2014 70(14) pp: 2478-2486
Publication Date(Web):
DOI:10.1016/j.tet.2013.11.082
Co-reporter:Jinze Li, Zheng Zhou, Li Ma, Guangxin Chen, and Qifang Li
Macromolecules 2014 Volume 47(Issue 16) pp:5739-5748
Publication Date(Web):August 14, 2014
DOI:10.1021/ma501100r
Stimuli-responsive polymers have been widely studied because of their potential use in nanocarriers and nanocontainers. In this study, a smart multistimuli responsive system was prepared through a light controlled supramolecular assembly. Mono cyclodextrin substituted isobutyl polyhedral oligomeric silsesquioxane (mCPOSS), an amphiphilic molecule, was synthesized by copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC), while azobenzene end-capped poly(ethylene glycol)-b-poly(2-(dimethylamino)ethyl methacrylate) copolymer (PEG-b-PDMAEMA-azo, PPA), a biocompatible pH/temperature-responsive macromolecule, was synthesized by atom transfer radical polymerization and CuAAC. The self-assembly process of PPA and mCPOSS in aqueous solution was as followed: first, mCPOSS self-assembled into a nanosphere in aqueous solution because of its amphipathic property; then, the trans-azo end groups of the PPA interacted with the cyclodextrin cavities on the nanosphere, and complex micelles were formed by the supramolecular assembly between PPA and mCPOSS. In addition, the morphology of the micelles could be adjusted by the ratio of PPA and mCPOSS, the formation and the dissociation of the micelles could be controlled by visible and ultraviolet light, and the size of the micelles could be tuned by pH.
Co-reporter:Li Ma;Jinze Li;Dan Han;Haiping Geng;Guangxin Chen;Qifang Li
Macromolecular Chemistry and Physics 2013 Volume 214( Issue 6) pp:716-725
Publication Date(Web):
DOI:10.1002/macp.201200590
Abstract
A series of polyhedral oligomeric silsesquioxane end-capped poly(spiropyran-containing methacrylate) (POSS–PSPMA) polymers, a kind of photoresponsive hybrid polymer, are synthesized via atom transfer radical polymerization. It is proved that the molecular weight of POSS–PSPMA is sharply increased by raising the proportion of methanol or the concentration of the reactants. The self-assembly behavior of POSS–PSPMA is studied in toluene: under the control of UV and visible light, POSS–PSPMA can reversibly self-assemble into aggregates because the charged merocyanines (MC) form stacks. These MC stacks act as non-covalent crosslinking points and POSS shell guarantees the stability of the aggregates. This system has a broad potential use in nanocarriers, especially for encapsulating and releasing polar substances in the nonpolar solvents.
Co-reporter:Nana Xie;Jinze Wang;Zhilong Guo;Guangxin Chen;Qifang Li
Macromolecular Chemistry and Physics 2013 Volume 214( Issue 15) pp:1710-1723
Publication Date(Web):
DOI:10.1002/macp.201300290
Co-reporter:Jing Wang, Fang Li, Qifang Li, Jianli Sun, Guang-Xin Chen
Thin Solid Films 2013 Volume 536() pp:191-195
Publication Date(Web):1 June 2013
DOI:10.1016/j.tsf.2013.04.002
This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy).This article has been retracted at the request of the corresponding authors and the Editor-in-Chief. The article is largely a duplication of a paper that has already been published in RSC Advances 2 (2012), pages 6637-6644; http://dx.doi.org/10.1039/C2RA20250F. One of the conditions of submission of a manuscript for publication is that the author declares explicitly that the paper has not been published yet or is not under consideration for publication elsewhere. As such, this article violated the guidelines.
Co-reporter:Jiangxuan Song;Junfeng Zhao;Yun Ding;Guangxin Chen;Xulong Sun;Da Sun;Qifang Li
Journal of Applied Polymer Science 2012 Volume 124( Issue 4) pp:3334-3340
Publication Date(Web):
DOI:10.1002/app.35259
Abstract
2,2-Bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane (Bis-GMA), one of the most important light-curable dimethacrylate resins, is widely used as dental restorative material. However, one problem of Bis-GMA is the high water sorption due to the hydrophilic hydroxyl (–OH) group, resulting in a short life in actual application. In this study, to overcome the drawback stated above, novel organic–inorganic dimethacrylate monomer containing polyhedral oligomeric silsesquioxanes (POSS), Bis-GMA-graft-POSS, is synthesized via the nucleophilic addition reaction of isocyanate functionalized POSS (IPOSS) and pendent hydroxyl group of Bis-GMA. Then the as-synthesized Bis-GMA-graft-POSS, of which hydroxyl group was substituted by hydrophobic POSS, is also introduced into the Bis-GMA/TEGDMA matrix to prepare a series of methacrylate-based hybrids for dental materials under visible light with camphorquinone and ethyl-4N,N-dimethy-laminobenzoae (EDMAB) as initiator and coinitiator, respectively. Compared to Bis-GMA/TEGDMA composites, water sorption of modified composites can be significantly reduced with the addition of Bis-GMA-graft-POSS. Moreover, the Bis-GMA/TEGDMA/POSS hybrids show hydrophobic surfaces, leading to much higher water contact angles than that of Bis-GMA/TEGDMA composites. The morphology of hybrids containing POSS was furthermore studied by X-ray diffraction (XRD) analysis and X-ray photoelectron spectroscopy (XPS). The results show that POSS disperses in the matrix in noncrystalline form and tend to migrate to the surface of the modified composites that lead to the lower water sorption and higher water contact angles. These results are very useful for design of novel methacrylate monomers and clinical application. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Guang-Xin Chen;Lingxia Si;Peng Lu;Qifang Li
Journal of Applied Polymer Science 2012 Volume 125( Issue 5) pp:3929-3935
Publication Date(Web):
DOI:10.1002/app.36400
Abstract
Polyhedral oligomeric silsesquioxane-containing hybrids of epoxy resins are prepared via the cocuring reaction between octaaminophenyl polyhedral oligomeric silsesquioxane (OAPS) and brominated epoxy resin (EP). The gel time, dispersion, thermal properties, mechanical properties, water absorption, and dielectric properties of the OAPS/EP composites are studied. The gel time of the 1 wt % OAPS composites is significantly higher compared with that of the epoxy resin control. Wide angle X-ray diffraction and scanning electron microscopy show that, at the molecular level, the appropriate amount of POSS cages was dispersed in the epoxy matrix because the POSS monomer participated in the crosslinking reaction. The thermal and mechanical properties of the composites are enhanced as 1 wt % OAPS was added to the epoxy system. The water absorption of the 1 wt % OAPS composite significantly declines. The dielectric constant of the 1 wt % OAPS composite is 0.5 less than that of the epoxy resin control in the range of 100 Hz–40 MHz. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Yun Ding;Guangxin Chen;Jiangxuan Song;Yunshu Gou;Jianjun Shi;Riguang Jin;Qifang Li
Journal of Applied Polymer Science 2012 Volume 126( Issue 1) pp:194-204
Publication Date(Web):
DOI:10.1002/app.36624
Abstract
In this study, supertoughened polyamide (PA) nanocomposites were prepared by the incorporation of epoxidized polyhedral oligomeric silsesquioxane (POSS) into the polyamide 6 (PA6)/methyl methacrylate–butadiene–styrene copolymer (MBS) blend via a melt-blending method. The effect of POSS on the rheological properties, mechanical properties, water uptake, and morphology of the hybrid PA6 nanocomposites was studied. The results show that under impact loading, the hybrid PA6 composites exhibited significant improvements in both the crack initiation energy and the crack propagation energy. This hybrid composite showed supertough behavior. Meanwhile, the tensile strength and the water absorption resistance was also improved with the addition of epoxidized POSS. The capillary and torque rheological results indicated that the epoxidized POSS, which acted as nanoscale ball bearings, significantly decreased the melt viscosity of the matrices and facilitated the melting process. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed to study the microstructure–property relationships of the hybrid PA6 composites. The TEM results showed that the MBS particles were dispersed homogeneously in the PA6 matrix. The mean diameter of the MBS particles decreased, and the size distribution of the MBS particles narrowed down with the introduction of the epoxidized POSS and compatiblizer. The SEM micrographs indicated that the impact fracture surfaces of the PA composites showed morphological characteristics of supertough polymers because of the synergistic effect of the functionalized POSS and compatibilized MBS particles. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Guang-Xin Chen;Haiping Geng;Lingling Luo;Bin Wu;Qi Fang Li
Journal of Applied Polymer Science 2012 Volume 126( Issue S1) pp:E109-E115
Publication Date(Web):
DOI:10.1002/app.36406
Abstract
The typical process used to synthesize expandable polystyrene was modified and applied to prepare water expandable polystyrene (WEPS)-starch copolymer. The maleic anhydride was used to improve the compatibility between starch and styrene. Various reaction conditions, weight ratio of styrene/water (O/W ratio), and starch content, were applied to obtain WEPS copolymer beads. Molecular weight, molecular weight distribution, glass transition temperature (Tg), and phase behavior of copolymer were investigated. With the increase of O/W ratio, the water content and molecular weight increased, whereas the molecular weight distribution and Tg of copolymer decreased. Molecular weight distribution and the Tg of the copolymer both increased as a function of starch content. The water content in the beads reached the maximum value at 6 wt % of starch content at same O/W ratio. The domain size of starch increased with the increase of the starch content. The domain size distribution of starch was best at 6 wt % of starch. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Jiangxuan Song;Guangxin Chen;Gang Wu;Chunhua Cai;Pinggui Liu;Qifang Li
Polymers for Advanced Technologies 2011 Volume 22( Issue 12) pp:2069-2074
Publication Date(Web):
DOI:10.1002/pat.1722
Abstract
Linear isocyanate-terminated poly(urethane-imide) (PUI) with combination of the advantages of polyurethane and polyimide was directly synthesized by the reaction between polyurethane prepolymer and pyromellitic dianhydride (PMDA). Then octaaminophenyl polyhedral oligomeric silsesquioxane (OapPOSS) and PUI were incorporated into the epoxy resin (EP) to prepare a series of EP/PUI/POSS organic–inorganic nanocomposites for the purpose of simultaneously improving the heat resistance and toughness of the epoxy resin. Their thermal degradation behavior, dynamic mechanical properties, and morphology were studied with thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA), and transmission electron microscope (TEM). The results showed that the thermal stability and mechanical modulus was greatly improved with the addition of PUI and POSS. Moreover, the EP/PUI/POSS nanocomposites had lower glass transition temperatures. The TEM results revealed that POSS molecules could self assemble into strip domain which could switch to uniform dispersion with increasing the content of POSS. All the results could be ascribed to synergistic effect of PUI and POSS on the epoxy resin matrix. Copyright © 2010 John Wiley & Sons, Ltd.
Co-reporter:Jiangxuan Song;Guangxin Chen;Yun Ding;Jianjun Shi;Ying Liu ;Qifang Li
Polymer International 2011 Volume 60( Issue 11) pp:1594-1599
Publication Date(Web):
DOI:10.1002/pi.3120
Abstract
The sol–gel process has been frequently employed for preparation of high performance silica/polymer composites. In this paper, novel sol–gel precursor triethoxysilane-terminated poly(urethane-imide) (PUI-Si), combining the advantages of polyurethane (PU) and polyimide, was synthesized and characterized. Then PUI-Si was incorporated into the epoxy resin matrix to prepare a series of EP/PUI-Si organic-inorganic hybrids through an in situ sol–gel process and crosslinking reactions. The thermal stability of EP/PUI-Si hybrids was evaluated by thermogravimetric analysis and the results show that the PUI-Si could significantly improve the thermal properties of epoxy resin. The initial decomposition temperature of composites with 50 wt% PUI-Si reached 347.1 °C, 157.3 °C higher than that of neat epoxy resin. Furthermore, the tensile strength and breaking elongation can also be clearly improved by adding a suitable amount of PUI-Si. Similarly, the water contact angle increased to 97.4° with 70 wt% PUI-Si, showing a hydrophobic surface. The morphology was investigated by transmission electron microscopy and the results reveal that the silica particles are smaller than 20 nm and have a strong interaction with the epoxy resin matrix, resulting in the above-mentioned high performance properties. Copyright © 2011 Society of Chemical Industry
Co-reporter:Li Ma, Haiping Geng, Jiangxuan Song, Jinze Li, Guangxin Chen, and Qifang Li
The Journal of Physical Chemistry B 2011 Volume 115(Issue 36) pp:10586-10591
Publication Date(Web):August 9, 2011
DOI:10.1021/jp203782g
Responsive polymeric micelles have been widely studied because of their potential use in nanocontainers and nanocarriers. In this study, polyhedral oligomeric silsesquioxane (POSS) end-capped poly[2-(dimethylamino)ethyl methacrylate] (POSS–PDMAEMA), a stimuli-responsive organic–inorganic hybrid polymer, was synthesized via atom transfer radical polymerization (ATRP) using POSS–Br as a macroinitiator. The self-assembly behaviors of POSS–PDMAEMA in aqueous solution were studied by fluorescence probe, transmission electron microscopy (TEM), dynamic light scattering (DLS), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD). The results revealed two self-assembly processes of POSS–PDMAEMA. First they self-assembled into a single micelle with the POSS molecules forming a crystal core and the PDMAEMA chains stretching as a corona. Then the single micelles, as building blocks, were able to reversibly form a hierarchical micelle-on-micelle structure (complex micelle) under external stimuli.
Co-reporter:Jing Wang, Guang-Xin Chen, Jianli Sun, and Qifang Li
The Journal of Physical Chemistry B 2011 Volume 115(Issue 12) pp:2824-2830
Publication Date(Web):March 10, 2011
DOI:10.1021/jp111115x
Polystyrene-functionalized C60 (C60-PS) was synthesized by atom-transfer radical polymerization. The structure of the hybrid was characterized by gel permeation chromatography and thermal gravimetric analysis. The self-assembly of polystyrene-block-poly(ethylene oxide) (PS-PEO)/C60-PS film in annealing solvents was studied on a silicon wafer and at the air/water interface by transmission electron microscopy. The method is an easy route to produce arrays of ordered nanostructures. The addition of C60-PS has a great effect on the self-assembly of PS-PEO. Treating the film under solvent vapor can modulate the orientation and ordering of PS-PEO microdomains. The C60-PS enhanced the formation of lamellae microstructure, and the C60-PS entered the PS phase, expanding the scale of PS domains. Nevertheless, it becomes more complex when it refers to the self-assembly at the air/water interface under solvent vapor for a long time. The selectivity of solvent to the polymer chains plays an important role as the annealing time increases.
Co-reporter:Jiangxuan Song;Gang Wu;Jianjun Shi;Yun Ding;Guangxin Chen
Macromolecular Research 2010 Volume 18( Issue 10) pp:944-950
Publication Date(Web):2010 October
DOI:10.1007/s13233-010-1009-8
Incorporating elastic polyurethane in epoxy resin (EP) can enhance the physico-chemical properties but deteriorate the thermal stability. Poly(urethane-imide) (PUI) with a high reactive function group (-NCO), which combines the advantages of polyurethane and polyimide, was synthesized to simultaneously improve the toughness and thermal stability of epoxy resin. EP/PUI composites were prepared based on epoxy resin and poly(urethaneimide) with 4,4-diaminodiphenylmethane as the curing agent using a simultaneous polymerization method. FTIR analysis confirmed the formation of EP-g-PUI interpenetrating polymer networks via a reaction between -NCO of poly(urethane-imide) and -OH of epoxy resin. The thermal stability and mechanical properties were examined by thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and stress-tensile method, respectively. Corresponding to the pure epoxy resin, which has three stage thermal decomposition, the resulting PUI/EP composite exhibits only one stage and has a much higher initial decomposition temperature (323.8°C) than that (189.8°C) of the epoxy resin. Moreover, the EP/PUI composite has a higher glass transition temperature, tensile strength and breaking elongation when 30 phr PUI was added. With increasing PUI content to 70 phr, the breaking elongation was 213 times higher than that of the neat epoxy resin. The morphology of these composites was also investigated further by scanning electronic microscopy (SEM) and transmission electron microscopy (TEM). The results showed that a grafted interpenetrating polymer network was formed.
Co-reporter:Yong Ma;You-Ping Wu;Li-Qun Zhang
Journal of Applied Polymer Science 2008 Volume 109( Issue 3) pp:1925-1934
Publication Date(Web):
DOI:10.1002/app.27714
Abstract
Rubber/organic clay (OC) nanocomposites were produced by melt blending. Polar or unsaturated matrices (e.g., NBR and SBR) could easily enter into OC layers, whereas using nonpolar unsaturated rubber (EPDM), without other additives' help, intercalation structure could not be directly obtained. For the EPDM system, an intercalated structure was observed in presence of stearic acid (SA) for composites composed of SA and OC. Transmission electron microscopy observation showed that the dispersion of clay in nonpolar saturated rubber matrix was much poorer than that in polar or unsaturated matrix. The same effect of polar matrix was confirmed by comparison between IIR/OC and BIIR/OC systems. Moreover, using OC pretreated by SA (S-OC), the dispersion of clay was obviously improved in the investigated nanocomposites, due to the intercalation of SA into OC interlayers. Especially in the nonpolar saturated EPDM system, the intercalation structure could be easily observed. Relative to the corresponding nanocomposites using OC, tensile strengths and the stresses at low strain of NBR and SBR based nanocomposites with S-OC were significantly improved; while with EPDM nanocomposite, using S-OC, only tensile strengths were improved but the stresses at low strain were almost the same, which should be related to the different interfacial force between OC and different rubber matrices. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Yu-fang ZHU, Jun-feng ZHAO, Xi WANG, Qi-fang LI
Chemical Research in Chinese Universities 2008 Volume 24(Issue 5) pp:570-574
Publication Date(Web):September 2008
DOI:10.1016/S1005-9040(08)60120-8
Abstract
Polyvinylcarbazole(PVK) composites containing organic-inorganic hybrid polyhedral oligomeric silsesquioxane(POSS) PVK-POSS were prepared by free radical polymerization. POSS monomers reacted with vinylcarbazole and were completely dispersed at molecular level in PVK matrix and PVK-POSS nanocomposites display higher glass transition temperature(Tg) in comparison with neat PVK. Optical properties of PVK/POSS nanocomposites were investigated by UV-spectrum and PL-spectrum and the results show that the PVK-POSS nanoparticles have a good interface effect and improve color purity effectively. The maximum absorption wavelength bathochromically shifts gradually with the increasing of the content of POSS. The luminescent intensity becomes higher and higher with the increase of POSS content, and reaches its maximum luminescent intensity when the POSS content is 3% (mass fraction), while some POSS-rich nanoparticles are present in matrix when contents of POSS are beyond 5%.
Co-reporter:Qi Fang Li;Riguang Jin;Kun Lu;Qingquan Yang
Journal of Applied Polymer Science 2006 Volume 100(Issue 3) pp:2293-2302
Publication Date(Web):17 FEB 2006
DOI:10.1002/app.22882
The curing reaction between the diepoxy and dicyanate mixed resins in the presence of three different catalysts Cu(AcAc)2, manganese octoate, and copper octoate was investigated. The thermal behavior was monitored using differential scanning calorimeter; the transformations of structures during the isothermal and heating process were explored by Fourier transform infrared spectroscopy; the changes of the carbonic-framework of polymer and intermediate products were analyzed by nuclear magnetic resonance. Conclusions can be drawn as follows: Similar to noncatalyzed system, the overall reaction still occurs in two steps: cyclotrimerization of cyanate ester to produce triazine rings, coupled with the formation of some secondary intermediate products, and coreaction of epoxy and triazine rings to form oxazolidinone rings at high temperature. The catalysts can accelerate the curing process and decrease the curing temperature as well as gel time, and manganese octoate presents the best effect on curing rate. But the mechanisms and the structures of intermediate products of metallic-catalyzed epoxy/cyanate are not changed by the addition of catalysts. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2293–2302, 2006
Co-reporter:Dan Bi, Qifang Li, Guang-Xin Chen
Applied Clay Science (January 2014) Volume 87() pp:
Publication Date(Web):1 January 2014
DOI:10.1016/j.clay.2013.11.019
•The novel clay was prepared by reacting POSS with the organic montmorillonite.•The layer spacing of POSS modified clay increased from 1.68 nm to 3.74 nm.•Poly(l-lactide)/POSS modified clay nanocomposite displayed a 31 °C increase in T5%.•Nanocomposite with 10 mass% clay showed a 61 % decrease in gas permeability.•Gas permeabilities of nanocomposites were predicted by phenomenological models.Novel montmorillonites (Mts) were prepared by reacting aminopolyhedral oligomeric silsesquioxane (POSS) with organic Mt (OMt). Poly(l-lactide) (PLLA)-based nanocomposites with Mt were produced by melt compounding. The effects of POSS modified OMt (POSS-OMt) on the gas transport, thermal properties, and morphology of PLLA were investigated. POSS in the interlayers of OMt exerted important effects on the properties of the clay polymer nanocomposites (CPN). XRD studies revealed that the layer spacing of OMt increased from 1.68 nm to 3.74 nm after intercalation with POSS. TEM findings indicated that the CPN consisted of a random dispersion of intercalated/exfoliated aggregates throughout the PLLA matrix. DSC results demonstrated that incorporation of 2 mass% POSS-OMt results in a significant increase in crystallization temperature. TGA studies further showed that the CPN prepared from POSS-OMt displays a 31.2 °C increase in decomposition temperature for 5% mass loss relative to virgin PLLA. Gas permeation analysis showed that increasing the Mt concentration in the polymer matrix leads to expected decreases in permeation values. The gas barrier properties of the CPN were comparable with those predicted by phenomenological models, such as those from Nielsen and Cussler.Download full-size image
Co-reporter:Lei Zhu, Min Wang, Bowen Li, Chao Jiang and Qifang Li
Journal of Materials Chemistry A 2016 - vol. 4(Issue 41) pp:NaN16072-16072
Publication Date(Web):2016/09/13
DOI:10.1039/C6TA07138D
Two novel conjugated polymers based on benzo[1,2-b:4,5-b′]dithiophene (BDT) and isoindigo units linked with a 3-octylthieno[3,2-b]thiophene unit as a π-bridge were designed and synthesized. The two polymers named PBDT-TT-IID and PBDTT-TT-IID with the same acceptor unit and different donor unit showed similar molecular weight, absorption spectrum range, and molecular energy levels. Introduction of a thienyl group in PBDTT-TT-IID increased the conjugation degree of the backbone, expanded the absorption spectrum and improved the hole mobility. The film absorption spectrum of PBDTT-TT-IID exhibited a strong shoulder peak at 697 nm, which is attributed to the strong aggregation and highly ordered packing of the polymer chains in the solid state. The power conversion efficiencies (PCEs) of the polymer solar cells (PSCs) based on PBDT-TT-IID and PBDTT-TT-IID achieved 6.31% and 8.05%, respectively. This is first time that efficiency over 8% based on isoindigo conjugated polymers in conventional devices, and it also has the possibility of further improvement. Moreover, these two polymers showed extremely high charge carrier transport including hole and electron mobilities on the 10−2 cm2 V−1 s−1 magnitude. This shows their potential as high efficiency materials in polymer solar cells.
Co-reporter:Jinze Li, Li Ma, Guangxin Chen, Zheng Zhou and Qifang Li
Journal of Materials Chemistry A 2015 - vol. 3(Issue 42) pp:NaN8409-8409
Publication Date(Web):2015/09/17
DOI:10.1039/C5TB01702E
Stimuli-responsive hydrogels are soft, biocompatible and smart biomaterials; however, the poor mechanical properties of the hydrogels limit their application. Herein, we prepared a reductant- and light-responsive polyurethane hydrogel which was made of polyethylene glycol, 1,6-diisocyanatohexane, azobenzene, cyclodextrin and disulfide. Attenuated Total Reflectance Infrared Spectra and 1H NMR were used to characterize the structure of the hydrogel. The hydrogel has a high elasticity (a tensile modulus of 36.5 ± 0.5 kPa and a storage modulus of 52.9 ± 1.2 kPa) at a high water content (91.2 ± 0.4%). Swelling, mechanical and rheological properties of the hydrogel can be tuned by the content of the crosslinker, light and reductant. The hydrogel has low cytotoxicity and it can be used for drug delivery. Ultraviolet irradiation helped to load drugs and the reductant accelerated the drug release. With its high mechanical properties and light- and reductant-responsiveness, the hydrogel is hopefully to be used as a drug carrier.
Co-reporter:Guangzhong Yin, Donglin Zhao, Ye Ren, Lianwei Zhang, Zheng Zhou and Qifang Li
Biomaterials Science (2013-Present) 2016 - vol. 4(Issue 2) pp:NaN318-318
Publication Date(Web):2015/11/16
DOI:10.1039/C5BM00414D
PLLA porous materials with high porosity were prepared by a gradual precipitation method and further modified by using different concentrations of gelatin aqueous solutions. Therefore, porous materials with different contents of gelatin coating were obtained. The micro morphology, crystallization, thermal performance, hydrophilicity and mechanical properties of the materials were evaluated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), thermogravimetric analysis (TGA), water uptake ability tests and compression tests. It was found that the modified materials were formed by the stacking of nanosheets. The materials can maintain more than 80% porosity, high water uptake abilities and fast water uptake rates after modification. The compressive moduli of the materials were significantly improved from the initial sample with a value of 0.57 MPa to 46.41 MPa with gelatin modification. Due to the high porosity of materials, interconnected pore structures, and good surface hydrophilicity, the materials were expected to be widely used in the field of tissue engineering scaffolds, especially for bone substitutes, mainly due to their tunable and excellent mechanical properties.
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