Polymer Chemistry
·
2016
·Vol. 7
·期 22
·3756-3765
·
IF 5.687
Mingguang Yu,Jianbo Tan,Jianwen Yang,Zhaohua Zeng
In a common RAFT dispersion polymerization induced self-assembly (PISA) formulation, R-type macro-RAFT agents with a solvophilic chain attached at the leaving group side are normally used to mediate the polymerization, meanwhile Z-type macro-RAFT agents with a solvophilic chain attached at the Z-group side are seldom employed. In this paper, we have tried to use a Z-type macro-RAFT agent (mPEG113-BTPA) to mediate RAFT dispersion polymerization of styrene, and found that the process exhibited a poorer PISA tendency and weaker molecular weight control. In comparison, we have conducted the same process mediated with an R-type macro-RAFT agent (mPEG113-DDMAT), and found that the formulation exhibited a typical PISA process, and nanoparticles were produced in situ. Further experiments suggest that the location of RAFT groups plays a key role for the PISA process in RAFT dispersion polymerization. The RAFT groups will be embedded in the produced particles when an R-type macro-RAFT agent is employed, but locate on the particle surface in the case of the Z-type macro-RAFT agent. We have tried to employ the RAFT groups on the surface of the mPEG113-BTPA stabilized particles to modify the particle surface, and successfully removed the solvophilic block via breaking the RAFT group, and generated the poly(dimethylacrylamide) block by surface-initiated RAFT polymerization. Based on the above mechanism perspective, we have designed a preliminary experiment, and found that well-defined monodisperse nanospheres could be prepared by heterogeneous RAFT dispersion polymerization mediated with a Z-type macro-RAFT agent-based block copolymer which was synthesized via pre-polymerization of styrene in 1,4-dioxane mediated with mPEG113-BTPA.
研究领域:
高分子化学
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胶体与界面科学
·
纳米材料
·
可控自由基聚合
·
自组装
·
药物递送系统
✓ 已验证
DOI
高影响因子
CELLULOSE
·
2018
·Vol. 25
·期 3
·1705-1714
·
IF 3.809
Liu Ting,Ding Enyong,Xue Feng
Polymer grafting is an efficient way to obtain functional cellulose nanocrystals. In this work, we used a “macro-RAFT (macromolecular reversible addition–fragmentation chain transfer) agent-assisted” strategy, which adds extra amount of amphiphilic macro-RAFT agent with low molecular weight to graft poly(N,N-dimethylacrylamide) (PDMA) from cellulose nanocrystals. Successful grafting was evidenced by different characterization methods, and a high weight ratio of grafted PDMA was obtained (77.6%). The grafting process was studied through the weight ratio of grafted PDMA, monomer conversion, and the molecular weight of free and grafted PDMA at different reaction time. As a result, we have suggested that there were three types of grafted polymer chains on cellulose nanocrystals in this reaction system and discussed their evolution during the grafting reaction. Finally, we summarized several key factors for successful grafting in this macro-RAFT agent-assisted strategy.
研究领域:
材料科学
·
高分子化学
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产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2022
·
IF 5.518
Shixian Zhang,Xinyu Ma,Yujie Zhu,Ruiwei Guo
A series of poly(acrylate polyether)s (RPA) was designed and synthesized by reversible addition-fragmentation chain transfer (RAFT) copolymerization , which were then used as dispersants for the dispersion copolymerization of styrene/acrylonitrile in polyethers in a semicontinuous approach to prepare graft polyether polyol (POP) with high solid content. The effects of structure, dosage, and feed ratio for macro-RAFT agent RPA on the stability, viscosity, and particle size of POP were examined and discussed. The dispersion polymerization process was also characterized by gradient elution polymer chromatography , and the results indicated that RPA was rapidly consumed and block-type stabilizer formed in the initial stage of polymerization. A portion of RPA added with monomer feeding provided better stability for the semicontinuous polymerization process.
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
CELLULOSE
·
2016
·Vol. 23
·期 6
·3717-3735
·
IF 3.195
Liu Ting,Xue Feng,Ding Enyong
Graft modification is an excellent way to prepare cellulose nanocrystals (CNCs) with various functions. In this work, different water-soluble macro reversible addition fragmentation chain transfer (macroRAFT) agents were used to mediate grafting of polyacrylamide with cellulose nanocrystals. Fourier-transform infrared spectroscopy, 13 C solid-state nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy, and elemental analysis were used to characterize the presence of polyacrylamide and quantify its content on the modified cellulose nanocrystals. The results show that two amphiphilic macroRAFTs, namely St 5 AA 14 RAFT and St 7 AA 14 RAFT, increased the weight ratio of polyacrylamide on the modified cellulose nanocrystals, whereas a corresponding hydrophilic macroRAFT (AA 14 RAFT) impeded growth of the polymer chains on the cellulose nanocrystals. Examination of the structure of the graft products and the cleaved polyacrylamide chains revealed that the amphiphilic macroRAFTs were involved in the graft reaction through effective chain transfer, thereby increasing the weight ratio of polyacrylamide on the modified CNCs.
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
MACROMOLECULAR CHEMISTRY AND PHYSICS
·
2022
·Vol. 224
·期 4
·2200369
·
IF 2.996
Weiwei Liu,Shuangkun Zhang,Zhi Luo,Tao Zou,Pingye Deng,Zhanpeng Wu,Haiqiao Wang
Novel thermoplastic fluorinated polyacrylate films possessing excellent mechanical performance are prepared by emulsion polymerization latex using adjustable amphiphilic star macro-reversible addition-fragmentation chain-transfer (macro-RAFT) agent as surfactants in this work. First, star macro-RAFT agent equipped with six amphiphilic arms is synthesized via two-step RAFT polymerization of acrylic acid (AA) and 2,2,2-trifluoroethyl acrylate (TFEA) in the presence of hexa-functional RAFT agents. The surface activities of the as-synthesized amphiphilic star macro-RAFT agents in aqueous solutions are studied. Subsequently, various fluorinated polyacrylate latexes are obtained by conducting emulsion polymerization of 2,2,3,4,4,4-hexafluorobutyl acrylate (HFBA) and butyl acrylate (BA) using the amphiphilic star macro-RAFT agents as both RAFT agents and surfactants. The latex particle morphologies are studied by transmission electron microscope (TEM) and particle size is measured by dynamic light scattering (DLS). The effects of PAA segment length, HFBA/BA mole ratio, and TFEA segment length on the surface morphologies of the fluorinated polyacrylate films are illustrated by investigating the surface properties using water contact angle test and atomic force microscopy (AFM). Finally, the elastomeric films obtained by directly casting the prepared fluorinated polyacrylate latexes show excellent comprehensive properties such as tensile strength over 4 MPa, elongation at break ≈700%, permanent deformation below 25%. Water absorption test is also provided as a reference.
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
JOURNAL OF POLYMER RESEARCH
·
2015
·Vol. 22
·期 4
·1-8
·
IF 1.92
Cheng Chuanjie,Bai Xiongxiong,Zhang Xu,Li Hongxia,Huang Qinghua,Tu Yuanming
A symmetric photo-active trithiocarbonate was designed and synthesized, which can act not only as a functional reversible addition-fragmentation chain transfer (RAFT) agent, but also as a crosslinker in crosslinking poly(methyl methacrylate- co -hydroxy ethyl acrylate) (poly(MMA- co -HEA)) due to interactions of benzophenone moieties of trithiocarbonate and hydroxyl groups of poly(MMA- co -HEA) under UV irradiation. In addition, the crosslinked poly(MMA- co -HEA) demonstrates photo-promoted self-healing properties by reshuffling C-S bonds of trithiocarbonate.
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
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2018
·
IF 2.829
Shaoling Bai,Yaqi Wang,Bin Liu,Yujie Zhu,Ruiwei Guo
Dispersion copolymerization of acrylamide (AM) and sodium 2-acrylamido-2-methylpropanesulfonate (AMPSNa) in aqueous ammonium sulfate (AS) solution was performed without mechanical stirring using a macro-RAFT agent sodium poly(2-acrylamido-2-methylpropanesulfonate) trithiocarbonate (PAMPSNa-TTC) as the stabilizer and 2,2′-azobis(2-methylpropionamide) dihydrochloride as the initiator. The effects of various polymerization parameters were systematically investigated regarding dispersion stability, particle size, molecular weight and apparent viscosity. A new mechanism for particle formation and the particle stability of aqueous dispersion polymerization was proposed.
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
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
JOURNAL OF POLYMER RESEARCH
·
2013
·Vol. 20
·期 7
·1-11
·
IF 2.019
Cheng Chuanjie,Bai Xiongxiong,Liu Shaojin,Huang Qinghua,Tu Yuanming,Wu Haiming,Wang Xiaoji
A cardanol-derived reversible addition-fragmentation chain transfer (RAFT) agent was synthesized in 57 % total yield, and a cardanol-based anionic surfactant was also facilely prepared. Emulsion polymerization of methyl methacrylate (MMA) was realized to form a cardanol-terminated PMMA polymer by using the novel RAFT agent as well as the cardanol-based anionic surfactant. To improve the properties of cardanol-terminated PMMA as a material, UV-curing was performed. According to the comprehensive behavior of the UV-cured resins, optimal irradiation time was 20 min.
研究领域:
材料科学
·
高分子化学
·
可持续化学
✓ 已验证
DOI
高影响因子
Journal of Macromolecular Science Part A-Pure and Applied Chemistry
·
2020
·
IF 1.349
Jia Liu,Jian Li,Chen Yi Wang,Qiang Ren
The effect of the hydrophobicity of block copolymer macro-RAFT agents on the controllability of RAFT surfactant-free cationic emulsion polymerization of styrene was investigated. Three different copolymers, poly(dimethyl aminoethyl acrylate) (PDMAEA), poly(dimethyl aminoethyl acrylate-co-styrene)-b-(butyl acrylate) (P(DMAEA-co-St)-b-PBA) and poly(dimethyl aminoethyl acrylate-co-styrene)-b-(hexafluorobutyl acrylate) (P(DMAEA-co-St)-b-PHFBA), which had different hydrophobicity in their hydrophobic segments, were synthesized and used as the macro-RAFT agents. When P(DMAEA-co-St)-b-PHFBA and P(DMAEA-co-St)-b-PBA were used as macro-RAFT agents, the RAFT surfactant-free cationic emulsion polymerization of styrene underwent very fast. But when the PDMAEA was used as the macro-RAFT agent, no polymerization of styrene was observed. The controllability of styrene polymerization with P(DMAEA-co-St)-b-PHFBA as the RAFT agent showed much better than that with P(DMAEA-co-St)-b-PBA as the macro RAFT agent. This was ascribed to hydrophobicity difference of the hydrophobic segment between P(DMAEA-co-St)-b-PHFBA and P(DMAEA-co-St)-b-PBA macro-RAFT agents. A mechanism explanation for the controllability of emulsion polymerization was proposed. The location of the active trithiocarbonate group of the macro-RAFT agent in micelle was supposed to be a key factor affecting the controllability of RAFT surfactant-free cationic emulsion polymerization of styrene. The hydrophobicity of the RAFT agent and nature of medium had impact on the location of the active trithiocarbonate group of the macro-RAFT agent in micelle and affected the polymerization controllability.
研究领域:
高分子化学
·
材料科学
·
化学工程
·
胶体与界面科学
✓ 已验证
DOI
高影响因子
Polymer Chemistry
·
2021
·Vol. 13
·期 7
·914-921
·
IF 5.582
Fei Deng,Menglin Yang,Yanli Zhang,Xiaohui Wu,Rujiang Ma,Feihe Ma,Linqi Shi
Refolding a denatured protein into its native form and stabilizing its structure are significant in the production and storage of protein products. The self-assembled mixed-shell polymeric micelle (MSPM) based nanochaperones closely mimic natural molecular chaperones in terms of structure and function and have been widely used to regulate the (re)folding of denatured proteins. However, the traditional manufacturing method of MSPM based nanochaperones is inconvenient with a very low concentration, which greatly restricts its large-scale applicability in practice. Here, we developed a one-pot strategy to synthesize high-concentration MSPMs for the mass preparation of nanochaperones to refold bulk denatured proteins and stabilize the structure of native proteins. The high-concentration MSPM is synthesized using two macro-RAFT agents to induce the polymerization and cross-linking of hydrophobic monomers. Through this one pot synthesis method, MSPMs with a concentration of 36.8 mg ml−1 are obtained, which is much higher than that obtained through the traditional method (0.5 mg ml−1). Moreover, the obtained MSPMs provide a good renaturation efficiency for the refolding of bulk denatured proteins and can stabilize native proteins for long-term storage. This strategy provides a simple method for the mass preparation of functional nanochaperones, which will promote its applications in practice.
研究领域:
生物化学
·
分子生物学
·
纳米医学
·
药物递送
·
蛋白质工程
·
高分子科学
✓ 已验证
DOI
高影响因子
ANALYTICAL CHEMISTRY
·
2021
·
IF 6.986
Qiong Hu,Luofeng Su,Zhuohua Chen,Yanyu Huang,Dongdong Qin,Li Niu
Trypsin is a key proteolytic enzyme in the digestive system and its abnormal levels are indicative of some pancreatic diseases. Taking advantage of the coenzyme-mediated electrografting of ferrocenyl polymers as a novel strategy for signal amplification, herein, a signal-on cleavage-based electrochemical biosensor is reported for the highly selective interrogation of trypsin activity at ultralow levels. The construction of the trypsin biosensor involves (i) the immobilization of peptide substrates (without free carboxyl groups) via the N-terminus, (ii) the tryptic cleavage of peptide substrates, (iii) the site-specific labeling of the reversible addition–fragmentation chain transfer (RAFT) agents, and (iv) the grafting of ferrocenyl polymers through the electro-RAFT (eRAFT) polymerization, which is mediated by potentiostatic reduction of nicotinamide adenine dinucleotide (NAD+) coenzymes. Through the NAD+-mediated eRAFT (NAD+-eRAFT) polymerization of ferrocenylmethyl methacrylate (FcMMA), the presence of a few tryptic cleavage events can eventually result in the recruitment of a considerable amount of ferrocene redox tags. Obviously, the NAD+-eRAFT polymerization is low-cost and easy to operate as a highly efficient strategy for signal amplification. As expected, the as-constructed biosensor is highly selective and sensitive toward the signal-on interrogation of trypsin activity. Under optimal conditions, the detection limit can be as low as 18.2 μU/mL (∼72.8 pg/mL). The results also demonstrate that the as-constructed electrochemical trypsin biosensor is applicable to inhibitor screening and the interrogation of enzyme activity in the presence of complex sample matrices. Moreover, it is low-cost, less susceptible to false-positive results, and relatively easy to fabricate, thus holding great potential in diagnostic and therapeutic applications.
研究领域:
分析化学
·
生物化学
·
生物技术
·
电化学
·
酶学
✓ 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）