MACROMOLECULES
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2016
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IF 5.554
Shaoning Liang,Xiaohui Li,Wen-Jun Wang,Bo-Geng Li,Shiping Zhu
We report the reversible addition–fragmentation chain transfer (RAFT) solution copolymerization of methyl methacrylate (MMA) with a cleavable divinyl comonomer, bis(2-methacryloyl)oxyethyl disulfide (BMAODS). 2-Cyano-2-propyldodecyl trithiocarbonate was used as a RAFT chain transfer agent and 2,2′-azobis(2-methylpropionitrile) as an initiator. The selective cleavage of BMAODS disulfide bonds was used to collect primary chains for the determination of the branching density (BD). The effects of initial monomer concentration, vinyl/divinyl ratio, and primary chain length on the branching and cyclization reactions were thoroughly investigated. It was found that more than 50% pendent double bonds from BMAODS were consumed in cyclization rather than in branching. The BD increased linearly with the conversion up to approximately 60% conversion. The monomer concentration was found to be the most efficient parameter in promoting branching. Increasing divinyl monomer ratio and primary chain length favored cyclization over branching. The work provides experimental evidence to support the random branching mechanism in RAFT copolymerization of vinyl and divinyl monomers.
研究领域:
高分子化学
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材料科学
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DOI
高影响因子
Polymers
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2017
·Vol. 9
·期 3
·89
·
IF 3.364
Fangjun Yao,Qingqing Liu,Zhengbiao Zhang,Xiulin Zhu
The impacts of hydrogen bonding on polymerization behavior has been of interest for a long time; however, universality and in-depth understanding are still lacking. For the first time, the effect of hydrogen bonding on the classical alternating-type copolymerization of styrene and maleimide was explored.N-phenylmaleimide (N-PMI)/styrene was chosen as a model monomer pair in the presence of hydrogen bonding donor solvent 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), which interacted with N-PMI via hydrogen bonding. Reversible addition-fragmentation chain transfer polymerization (RAFT) technique was used to guarantee the “living” polymerization and thus the homogeneity of chain compositions. In comparison with the polymerization in non-hydrogen bonding donor solvent (toluene), the copolymerization in HFIP exhibited a high rate and a slight deviation from alternating copolymerization tendency. The reactivity ratios of N-PMI and St were revealed to be 0.078 and 0.068, respectively, while the reactivity ratios in toluene were 0.026 and 0.050. These interesting results were reasonably explained by using computer simulations, wherein the steric repulsion and electron induction by the hydrogen bonding between HFIP and N-PMI were revealed. This work first elucidated the hydrogen bonding interaction in the classical alternating-type copolymerization, which will enrich the research on hydrogen bonding-induced polymerizations.Keywords:alternating copolymerization;hydrogen bonding;N-phenylmaleimide;fluoroalcohol;reversible addition-fragmentation chain transfer (RAFT) copolymerization
研究领域:
高分子化学
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物理化学
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DOI
PubMed
高影响因子
ACS Applied Materials & Interfaces
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2024
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IF 8.3
Shengjie Liu,He Yang,Xingyu Heng,Lihua Yao,Wei Sun,Qing Zheng,Zhaoqiang Wu,Hong Chen
To effectively solve the problem of significant loss of transplanted cells caused by thrombosis during cell transplantation, this study simulates the human fibrinolytic system and combines metabolic oligosaccharide engineering with strain-promoted azide–alkyne cycloaddition (SPAAC) click chemistry to construct a cell surface with fibrinolytic activity. First, a copolymer (POL) of oligoethylene glycol methacrylate (OEGMA) and 6-amino-2-(2-methylamido)hexanoic acid (Lys) was synthesized by reversible addition–fragmentation chain transfer (RAFT) copolymerization, and the dibenzocyclooctyne (DBCO) functional group was introduced into the side chain of the copolymer through an active ester reaction, resulting in a functionalized copolymer DBCO-PEG4-POL with ε-lysine ligands. Then, azide functional groups were introduced onto the surface of HeLa model cells through metabolic oligosaccharide engineering, and DBCO-PEG4-POL was further specifically modified onto the surface of HeLa cells via the SPAAC “click” reaction. In vitro investigations revealed that compared with unmodified HeLa cells, modified cells not only resist the adsorption of nonspecific proteins such as fibrinogen and human serum albumin but also selectively bind to plasminogen in plasma while maintaining good cell viability and proliferative activity. More importantly, upon the activation of adsorbed plasminogen into plasmin, the modified cells exhibited remarkable fibrinolytic activity and were capable of promptly dissolving the primary thrombus formed on their surfaces. This research not only provides a novel approach for constructing transplantable cells with fibrinolytic activity but also offers a new perspective for effectively addressing the significant loss of transplanted cells caused by thrombosis.
研究领域:
生物化学
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细胞生物学
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材料科学
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药学
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生物医学工程
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DOI
PubMed
高影响因子
Polymer Chemistry
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2022
·Vol. 13
·期 14
·2026-2035
·
IF 5.364
Wencheng Shi,Boyu Wu,Xiaofeng Guo,Anchao Feng,San H. Thang
Fluorescent end-functional mikto-arm star copolymers were prepared by an “arm-first” approach mediated by a mixture of macro-RAFT agents. RAFT copolymerization of coumarin-POEGMA, boron-dipyrromethene (BODIPY)-PDMA and bisindolylmaleimide (BIM)-PNIPAM with different fluorophore-labeled end-groups was performed with polyethylene glycol diacrylate as a cross-linker. The fluorescence spectra of fluorophore-labeled homopolymers showed that there was a good linear correlation existing between fluorescence intensity and polymer concentration in dilute solutions. According to the fluorescence results, after carefully choosing the peaks and calculation, the arm components of star polymers can be quantitatively analyzed with obvious similarity to 1H NMR approaches which are considered to be less valid in a complicated chemical environment. Overall, it is reasonably expected that the current study expands the characterization methods for star polymers and promotes the development of the synthesis of well-defined multifunctional star polymers.
研究领域:
聚合物科学
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材料化学
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分析化学
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DOI
高影响因子
ACS Applied Polymer Materials
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2023
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IF 5
Yongming Zeng,Tianchi Xu,Xiao-Fang Hou,Jiang Liu,Changqing Liu,Zhaosen Chang,Jianglin Fang,Dongzhong Chen
To achieve convenient storage of bioactive materials such as protein enzymes (proteases) at ambient temperature, with both their spatial structure and biocatalytic activity well retained, is highly appealing but challenging. Herein, a variety of amphiphilic random copolymers have been well synthesized via reversible addition–fragmentation chain transfer (RAFT) copolymerization of sulfobetaine methacrylate (SBMA) and various length fluoroalkyl methacrylate monomers. By simultaneously introducing fluoroalkyl and zwitterionic segments in random copolymerization, such kinds of amphiphilic random copolymers combined the advantages of both polyzwitterionic and fluoropolymers, which were capable of constructing uniform tiny single-chain nanoparticles (SCNPs) of around 10 nm in a wide range of compositions and fabrication conditions from aqueous solutions. Through intramolecular self-folding of the fluorinated alkyl segments to constitute the compact inner cores and the superhydrophilic zwitterionic SBMA polymer segments forming the outer passivated layer, the thus obtained SCNPs exhibited remarkable enzyme stabilizing capability through morphological adjustment, hydration, and heterocoagulation mechanisms for the investigated glucose oxidase (GOx) and horse radish peroxidase (HRP), acting like artificial molecular chaperones. Moreover, enzyme catalytic activity enhancement in the HRP@SCNPs system was well demonstrated with a representative enzyme-catalyzed cascade oxidization reaction for the synthesis of an azobenzene chromophore. Therefore, this work provides a facile fabricating strategy for SCNPs from well-synthesized amphiphilic random copolymers via RAFT, which may serve as promising stabilizers for ambient temperature storage and activity preservation of proteases.
研究领域:
聚合物化学
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生物化学
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材料科学
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纳米技术
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DOI
高影响因子
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