CARBOHYDRATE POLYMERS
·
2022
·
IF 10.723
Zhiqiang Wang,Lujun Zhang,Jiajun Feng,Pengfei Tang,Shuaishuai Chen,Hanqing Yu,Yueyao Hu,Zhongkai Wang,Feng Jiang
In this work, a chitin-based macromolecular chain transfer agent (Chitin-CTA) was designed to graft polymers from chitin at the molecular level. Homogeneous reversible addition-fragmentation chain transfer (RAFT) polymerization was performed to prepare branched MA elastomers , chitin- graft -poly(methyl acrylate) (Chitin- g -PMA) copolymers , which were thermally stable and showed tunable glass transition temperatures . These ultra-stretchable branched MA elastomers exhibit unique strain-hardening behavior and significantly enhanced mechanical properties. Mechanical tests indicate that the chitin backbones in branched MA elastomers can act as cross-linking points to improve the tensile strength , toughness, and elasticity simultaneously. The macroscopic performance of branched MA elastomers c be further promoted by introducing hydrogen bonding as non-covalent interaction to form an additional reversible physical network. This robust and versatile grafting strategy can provide new opportunities to prepare chitin-based branched MA elastomers with extraordinary mechanical properties.
研究领域:
材料科学
·
高分子化学
·
机械工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MOLECULAR STRUCTURE
·
2016
·
IF 1.78
Binbin Yu,Zhong Zeng,Qinyu Ren,Yang Chen,Mei Liang,Huawei Zou
A series of block type polycarboxylate-based superplasticizers (PCs) with different molecular architectures were synthesized with macromonomer butenyl alkylene polyoxyethylene-polyoxypropylene ether (BAPP) and acrylic acid (AA) by reversible addition–fragmentation chain transfer (RAFT) polymerization. Fourier-Transformed Infrared (FTIR) Spectroscopy and dynamic light scattering (DLS) were applied to investigate the PCs’ molecular structure. The dispersion capacity of the PCs in cement were also measured, and the results showed that the polycarboxylic dispersing agents prepared by this method were suitable for portlant cement. It was found that the PCs could affect the hydration process, which was performed through retarding the generation of ettringite in the hydrated product. Our studies with X-ray diffraction (XRD), scanning electron microscopy (SEM) and compressive strength measurement of hydrated production were all supporting this conclusion.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
POLYMER
·
2015
·
IF 3.562
Huanhuan Liu,Xiao Jiang,Rongjian Bian,Min Tong,Dandan Tang,Xiangdong Zhou,Youliang Zhao
Controlled synthesis of A 2m B 2n -type (m ≈ n ≈ 8) starlike copolymers comprising an oligomeric poly(styrene- co -maleimide) core and two types of V-shaped arms individually generated by ATRP and ROP was described. Multistep syntheses involving RAFT copolymerization , end group removal, ATRP of vinyl monomers such as styrene (St), methoxyethyl methacrylate (MEMA) and tert -butyl acrylate ( t BA), and ROP of ε -caprolactone (CL) were used to construct the target miktoarm stars with controlled molecular weight and relatively low polydispersity (PDI = 1.07–1.22). The resultant star copolymers had high bromide functionality and uniform chain length of ATRP-generated arms, evident from chain extension polymerization and cleavage of arms. Meanwhile, a pH-responsive (PAA) 2m (PCL) 2n star was also obtained by selective hydrolysis. The synthetic strategy via combination of RAFT copolymerization and “core first” approach is versatile in constructing various A 2m B 2n stars, and this study further paves way for facile synthesis and properties of new types of miktoarm stars.
研究领域:
高分子化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POLYMER RESEARCH
·
2017
·Vol. 24
·期 5
·1-9
·
IF 1.615
Xue Sheng,Yang Haicun,Ma Wenzhong,Gong Fanghong,Tao Guoliang,Liu Chunlin,Pan Ji
Poly(methyl methacrylate) brushes grafted from attapulgite nanoparticles (ATP@PMMA) were prepared by R-Supported reversible addition-fragmentation chain transfer polymerization (RAFT). ATP was firstly activated, and allowed to react with γ-aminopropyltriethoxysilane (APTES), 4,4′-azobis(4-cyanovaleric acid) (ACVA) and bis(thiobenzoyl) disulfide stepwise to afford 4-cyanopentanoic acid dithiobenzoate functionalized ATP (ATP-CPADB). Then, RAFT polymerizations of MMA mediated by the different systems were conducted and compared systemically. The grafting process was verified by FTIR, XRD, XPS, TGA and TEM data. Kinetic behavior indicated that the anchored CPADB is more effective before diffusing into the bulk phase. The grafting ratio ( G
r ), while M
n of grafted and free polymer increased linearly with increasing monomer conversion in presence of free CPADB, giving the hybrid particles with more homogeneous distribution of grafted polymer layer.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
MACROMOLECULES
·
2011
·
IF 4.838
Yanwu Zhou,Junpo He,Changxi Li,Linxiang Hong,Yuliang Yang
The thermal decomposition of different classes of RAFT/MADIX agents, namely dithioesters, trithiocarbonates, xanthates, and dithiocarbamates, were investigated through heating in solution. It was found that the decomposition behavior is complicated interplay of the effects of stabilizing Z-group and leaving R-group. The mechanism of the decomposition is mainly through three pathways, i.e., β-elimination, α-elimination, and homolysis of dithiocarbamate (particularly for universal RAFT agent). The most important pathway is the β-elimination of thiocarbonylthio compounds possessing β-hydrogen, leading to the formation unsaturated species. For the leaving group containing solely α-hydrogen, such as benzyl, α-elimination takes place, resulting in the formation of (E)-stilbene through a carbene intermediate. Homolysis occurs specifically in the case of a universal RAFT agent, in which a thiocarbonyl radical and an alkylthio radical are generated, finally forming thiolactone through a radical process. The stabilities of the RAFT/MADIX agents are investigated by measuring the apparent kinetics and activation energy of the thermal decomposition reactions. Both Z-group and R-group influence the stability of the agents through electronic and steric effects. Lone pair electron donating heteroatoms of Z-group show a remarkable stabilizing effect while electron withdrawing substituents, either in Z- or R-group, tends to destabilize the agent. In addition, bulkier or more β-hydrogens result in faster decomposition rate or lower decomposition temperature. Thus, the stability of the RAFT/MAIDX agents decreases in the order where R is (with identical Z = phenyl) −CH2Ph (5) > −PS (PS-RAFT 15) > −C(Me)HPh (2) > −C(Me)2C(═O)OC2H5 (7) > −C(Me)2Ph(1) > −PMMA (PMMA-RAFT 16) > −C(Me)2CN (6). For those possessing identical leaving group such as 1-phenylethyl, the stability decreases in the order of O-ethyl (11) > –N(CH2CH3)2 (13) > –SCH(CH3)Ph (8) > −Ph (2) > −CH2Ph (4) > −PhNO2 (3). These results consort with the chain transfer acitivities measured by the CSIRO group and agree well with the ab initio theoretical results by Coote. In addition, the difference between thermal stabilities of the universal RAFT agents at neutral and protonated states has also been demonstrated.
研究领域:
化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Polymer Chemistry
·
2016
·Vol. 7
·期 19
·3259-3267
·
IF 5.687
Jiemei Zhou,Wenjian Zhang,Chunyan Hong,Caiyuan Pan
Reversible addition–fragmentation chain transfer (RAFT) dispersion copolymerization of styrene (St) and methyl methacrylate (MMA) is conducted in methanol using poly(2-hydroxyethyl acrylate) (PHEA) as a macro chain transfer agent (macro-CTA). Compared with the general macro-CTA mediated alcoholic dispersion polymerization of St, RAFT dispersion copolymerization of St and MMA can promote the morphology transition of di-block copolymer nano-objects. Three phase diagrams are constructed by changing the molar ratio of St/MMA to reflect the relationship between the degree of polymerization (DP) of P(St-co-MMA), solids concentration and morphology of obtained nano-materials, and it is found that the phase diagrams could be affected by the molar ratio of St/MMA. Ultra-sensitive differential scanning calorimetry (US-DSC) is employed to determine the glass transition temperature (Tg) of polymeric nano-objects in methanol, and the result shows that the Tg values decrease with the increase of the molar content of MMA units in copolymers. Introduction of MMA units into the solvophobic block can enhance its mobility in methanol, which is beneficial for the morphology transition of di-block copolymer nano-objects.
研究领域:
高分子化学
·
纳米材料科学
✓ 已验证
DOI
高影响因子
COMPOSITES SCIENCE AND TECHNOLOGY
·
2016
·
IF 3.897
Yusheng Tang,Shuang Xu,Yunchuan Xie,Junwei Gu,Zhimei Song,Feng Gao,Jie Kong
Surface initiated reversible addition–fragmentation chain transfer polymerization (RAFT) of glycidyl methacrylate (GMA) was conducted on ceramic particles (ZNT). Then the ZNT@PGMA particles were introduced into cyanate ester (CE) matrix to prepare the ultra low dielectric loss ZNT@PGMA/CE composites. The ZNT@PGMA particles can be well dispersed in the CE matrix, resulting in the improvement of glass transition temperature by 40 °C and the increase of storage modulus by 130% in comparison to that of pure CE resins. The introduction of ZNT@PGMA particles can obviously decrease dielectric loss value of the ceramic/CE composites by one order of magnitude, which possesses potential in wave transparent composites and structures.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2025
·Vol. 17
·期 4
·515
·
IF 4.9
Yulan Wu,Jie Huang,Zanru Guo,Qian Yang,Chunmiao Xia,Zhenan Zheng
Porous polymer membranes with highly interconnected open-cellular structure and high toughness are crucial for various application fields. Polymerized high internal phase emulsions (polyHIPEs), which usually exist as monoliths, possess the advantages of high porosity and good connectivity. However, it is difficult to prepare membranes due to brittleness and easy pulverization. Copolymerizing acrylate soft monomers can effectively improve the toughness of polyHIPEs, but it is easy to cause emulsion instability and pore collapse. In this paper, stable HIPEs with a high content of butyl acrylate (41.7 mol% to 75 mol% based on monomers) can be obtained by using a composite emulsifier (30 wt.% based on monomers) consisting of Span80/DDBSS (9/2 in molar ratio) and adding 0.12 mol·L−1CaCl2according to aqueous phase concentration. On this basis, polyHIPE membranes with high open-cellular extent and high toughness are firstly prepared via reversible addition–fragmentation chain transfer (RAFT) polymerization. The addition of the RAFT agent significantly improves the mechanical properties of polyHIPE membranes without affecting open-cellular structure. The toughness of polyHIPE membranes prepared by RAFT polymerization is significantly enhanced compared with conventional free radical polymerization. When the molar ratio of butyl acrylate/styrene/divinylbenzene is 7/4/1, the polyHIPE membrane prepared by RAFT polymerization presents plastic deformation during the tensile test. The toughness modulus reaches 93.04 ± 12.28 kJ·m−3while the open-cellular extent reaches 92.35%, and it also has excellent thermal stability.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Applied Polymer Materials
·
2021
·
IF 4.089
Jian Sun,Chang Wang,Yu-Lin Hong,Zhi-Wei Tan,Cheng-Mei Liu
Reactive polymers with two or more reactive groups in each repeat unit were less reported, and these kinds of polymers were regarded as useful precursors for further multifunctionalization. Here, an alkali-soluble polymer with the bis(hydroxymethyl)phosphine oxide pendant group was first prepared by reversible addition–fragmentation transfer (RAFT) polymerization from a phosphine-containing monomer, namely (4-vinylbenzyl)-bis-hydroxymethyl phosphine oxide (VBzBHPO). The well-defined homopolymers were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and gel permeation chromatography. The molecular weights of both homopolymers and block polymers can be designed by changing RAFT polymerization parameters while still maintaining the narrow molecular weight distributions (mostly Mw/Mn < 1.2). The linear polymerization kinetics and successful chain extension polymerization with styrene or VBzBHPO confirmed the features of controlled/living radical polymerization. Attractively, the resulting polyVBzBHPO showed high solubility in alkaline solution but only lightly swelled in pure water. Such a distinguishing feature of the polymer material provided the possibility of carrying out post-polymerization modification in water with high functionality density and high modification efficiency.
研究领域:
高分子化学
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2016
·Vol. 134
·期 10
·
IF 1.866
Fei Fang,Fan Kong,Xueqin Zhang,Mengqi Lin,Yichi Zhang,Shounian Ding
A series of amphiphilic poly(N-vinyl carbazole) (PVK) block copolymers containing tris(8-hydroxyquinoline) aluminum (Alq 3 ) have been synthesized via reversible addition-fragmentation chain transfer (RAFT) radical polymerization with trithiocarbonate terminated polyethylene glycol (PEG) as a RAFT agent. The chemical structures of the block copolymers have been identified by 1 H nuclear magnetic resonance and Fourier transform infrared spectrometer. The analysis of gel permeation chromatography indicates that the polydispersity indices of the block copolymers are lower than 1.30. The results of thermogravimetric analysis show that the decomposition temperatures of the copolymers are higher than 330 ° C . The optical properties of the copolymers have been investigated and the obviously enhanced emission from Alq 3 has been found due to resonance energy transfer from PVK to Alq 3 . © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44573.
研究领域:
高分子化学
·
材料科学
·
光电子学
·
纳米功能材料
·
聚合物合成
·
荧光材料
·
能量转移
✓ 已验证
DOI
高影响因子
Polymer Chemistry
·
2015
·Vol. 6
·期 40
·7171-7178
·
IF 5.52
Wuxue Zhao,Zongsheng Hou,Zhaoquan Yao,Xiaodong Zhuang,Fan Zhang,Xinliang Feng
Two-dimensional hyper-cross-linked microporous polymers (2D HCPs) have been readily synthesized by emulsion polymerization using trithiocarbonate functionalized graphene oxide as a 2D reversible addition–fragmentation chain transfer (RAFT) agent. After a gel-type and permanently porous poly(vinylbenzyl chloride-co-divinylbenzene) precursor resin was grafted to the graphene surface, an FeCl3-promoted Friedel–Crafts reaction was carried out for benzyl chloride groups to construct a porous structure confined within 2D nanosheets. The resulting HCPs exhibited superhydrophobic behavior, and had a predominance of micropores with a specific surface area of up to 1224 m2 g−1. Moreover, they showed improved thermal stability in comparison with unadorned HCPs obtained without using the graphene template. Their H2 and CO2 capacities at 77 and 273 K reached 1.27 and 9.74 wt%, respectively, at a relative pressure of 0.99. In addition, the as-synthesized 2D HCPs were used as carbon precursors to generate 2D porous carbons with a high specific surface area (871 m2 g−1) and high-performance electrochemical energy storage (144 F g−1 at 0.5 A g−1).
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2023
·
IF 8.2
Jiao He,Lin Yun,Xinjian Cheng
Chitosan as the plentiful and easily available natural polymer, its solubility in organic solvents is still a challenge. In this article, three different chitosan-based fluorescent co-polymers were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization. They could not only dissolve in several organic solvents, but also could selectively recognize Hg 2+ /Hg + ions. Firstly, allyl boron-dipyrrolemethene (bodipy) was prepared, and used as one of the monomers in the subsequent RAFT polymerization. Secondly, chitosan-based chain transfer agent (CS-RAFT) was synthesized through classical reactions for dithioester preparation. Finally, three methacrylic ester monomers and bodipy bearing monomers were polymerized and grafted as branched-chains onto chitosan respectively. By RAFT polymerization, three chitosan-based macromolecular fluorescent probes were prepared. These probes could be readily dissolved in DMF, THF, DCM , and acetone. All of them exhibited the ‘turn-on’ fluorescence with selective and sensitive detection for Hg 2+ /Hg + . Among them, chitosan-g-polyhexyl methacrylate-bodipy (CS-g-PHMA-BDP) had the best performance, its fluorescence intensity could be increased to 2.7 folds. In addition, CS-g-PHMA-BDP could be processed into films and coatings. When loading on the filter paper, fluorescent test paper was prepared and it could realize the portable detection of Hg 2+ /Hg + ions. These organic-soluble chitosan-based fluorescent probes could enlarge the applications of chitosan.
研究领域:
材料科学
·
分析化学
·
生物医学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）