MACROMOLECULAR CHEMISTRY AND PHYSICS
·
2021
·Vol. 223
·期 3
·2100340
·
IF 2.527
Jianxiong Zhang,Junjin Duan,Dong Chen,Yuhong Ma,Wantai Yang
A direct photolysis reversible addition-fragmentation chain transfer (RAFT) polymerization of (meth)acrylates is developed with 2-cyano-2-propyldodecyl trithiocarbonate (TTP), which plays the dual role as photoinitiator and chain transfer agent. The polymerizations can be efficiently activated by blue light while maintaining a linear increase in M n versus conversion. With poly(methyl methacrylate)-TTP (PMMA-TTP, M n = 6700 g mol –1 , Ð = 1.29) as precursor, a higher molecular weight PMMA ( M n = 14 600 g mol –1 , Ð = 1.67) by chain extension, and a series of block copolymers, including poly(methyl methacryalte)- b -poly(glycidyl methacrylate), poly(methyl methacrylate)- b -poly(tert-butyl methacrylate), and poly(methyl methacrylate)- b -poly(benzyl meacrylate)(PMMA- b -PBnMA), are prepared. The M n,NMR = 14 900 g mol –1 of PMMA- b -PBnMA measured by NMR is very close to M n,GPC = 14 200 g mol –1 determined by gel permeation chromatography. Furthermore, the polymerization of acrylates exhibits higher controllability in regarding to dispersity ( Ð < 1.20) compared to those of polymethacrylates ( Ð = 1.10–1.80). With poly(methyl acrylate) (PMA-TTP, M n = 11 900 g mol –1 , Ð = 1.09) as macro-RAFT agent, a higher molecular weight PMA ( M n = 23 500 g mol –1 , Ð = 1.28) by chain extension, and PMA- b -PBnA ( M n = 26 500 g mol –1 , Ð = 1.19) are also prepared. A positive synergic effect is demonstrated by enhanced apparent polymerization rates at elevated temperature. For example, the apparent polymerization rates of MA increases from 0.0860 to 0.115 h –1 with temperature rising from 32 to 50 °C.
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Polymer Chemistry
·
2021
·Vol. 12
·期 39
·5574-5582
·
IF 5.582
Qianqian Ge,Guangzu Wang,Xiang Zhu,Weisheng Yu,Jiahui Zhou,Bin Wu,Yahua Liu,Zhengzhi Zheng,Zhengjin Yang,Jiasheng Qian
Polyolefin-based anion exchange membranes have recently been increasingly studied, but obtaining polyolefins with controllable molecular weights and high chemical stability under facile and metal-free conditions remains a critical challenge. Here, we demonstrate a novel strategy of exploiting visible light-induced reversible addition–fragmentation chain transfer polymerization (Vis-RAFT) for the preparation of poly(2-chloroethyl vinyl ether) (PCEVE), which exhibits high alkaline stability. With this strategy, we can control the molecular weight of PCEVE by an “on/off” light procedure. The quaternization of PCEVE yields quaternized poly(2-chloroethyl vinyl ether) (PQEVE) membranes with a well-defined microphase-separated morphology, a high chloride conductivity of 26.1 mS cm−1 at 30 °C, and a significantly reduced water swelling of 1.2% at 80 °C. We anticipate that this strategy can be a potent alternative to metal-catalysed coordination polymerization or metathesis polymerization in preparing high molecular weight polyolefins for membrane applications.
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JOURNAL OF POROUS MATERIALS
·
2019
·Vol. 27
·期 1
·95-105
·
IF 1.947
Xu Xiang,Zeng Yanning,Yu Caili,Zhang Faai
A series of mesoporous SBA-15 with various pore diameter (8, 15, 22 and 27 nm) were synthesized and used as “microreactor”. Reversible addition–fragmentation chain transfer (RAFT) polymerization of methyl methacrylate (MMA) was conducted in the channels of SBA-15 using azodiisobutyronitrile (AIBN) as initiator, ethyl xanthate ethyl propionate as chain transfer agent. The obtained PMMA/SBA-15 composites and neat PMMAs from composites were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption and desorption, Fourier transform infrared spectroscopy, thermogravimetry analysis, differential scanning calorimetry, hydrogen nuclear magnetic resonance. Results showed that compared with PMMA from conventional RAFT polymerization, PMMAs obtained from internal SBA-15 featured with narrower molecule weight distribution (1.34–1.55) and higher thermal stability due to confinement effects. With the increment of pore size of SBA-15, the molecular weight and glass transition temperature (T g ) of PMMA obtained from internal SBA-15 were distinctly improved whereas isotacticity of the PMMA decreased. The properties of the PMMA were managed with controllable RAFT polymerization by regulation the pore size of SBA-15.
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高影响因子
POLYMER
·
2018
·
IF 3.483
Yanming Lin,Ling Wang,Jinsheng Zhou,Lin Ye,Huiyuan Hu,Zhongkuan Luo,Li Zhou
In this study, we grafted brush-like CBMA copolymer brushes onto the surface of PVA hydrogel membrane through photo-induced electron transfer–reversible addition fragmentation chain transfer (PET-RAFT) polymerization. ATR-FTIR, XPS , AFM , UV–Vis absorption spectra and elemental analysis were adopted to characterize the hydrogels, and equilibrium swelling, water contact angle, vitro cytotoxicity assay, protein adsorption and cells adhesion experiments were used to evaluate the related property of hydrogels. The results of ATR-FTIR and XPS showed that pCBMA was successfully grafted onto the surface of PVA hydrogel membrane. The Ra roughness of hydrogel surface in AFM increased slightly from 5.44 nm to 6.12 nm. Transmittance of the PVA-g-pCBMA hydrogel in the visible range (380 nm-780 nm) was remaining at 91.2%–97.0%. The optimal reaction conditions (CPADB: 1.20 mmol/L, Eosin Y: 0.03 mmol/L and CBMA : 358 mmol/L) were confirmed through control experiments. The equilibrium swelling and water contact angle showed that the swelling ratio increased from 2.06 cm 3 g −1 to 3.65 cm 3 g −1 , while the water contact angle decreased from 45.94° to 18.06° with the increase of grafting ratio (23.92%–55.18%). In vitro cytotoxicity assay by CCK-8 showed that the cells relative viability remained at least 90.55%. Anti-protein adsorption experiment illustrated approximately 57.2% improvement of anti-protein capacity at 37 °C, while cells adhesion experiment also showed about 64.57% improvement of anti-cells capacity. These results revealed the applicability of the oxygen tolerant PET-RAFT mechanism on the PVA modification and it was effective, feasible and non-cytotoxic method to prepare the other functional PVA hydrogel membrane.
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JOURNAL OF CONTROLLED RELEASE
·
2018
·
IF 7.877
Hao-Ran Jia,Ya-Xuan Zhu,Ke-Fei Xu,Xiaoyang Liu,Fu-Gen Wu
The past decade has witnessed a growing number of nanoparticulate drug delivery systems for cancer treatment. However, insufficient cellular uptake by cancer cells and the undesirable endo/lysosomal entrapment of internalized therapeutic drugs remain the “Achilles heel” of many developed nanoagents. Here, we develop a novel lipid raft-responsive and light-controllable polymeric drug for efficient cytosolic delivery of photosensitizers . Conjugating a photosensitizer protoporphyrin IX (PpIX) to a polyethylene glycol-cholesterol polymer affords the amphiphilic drug (denoted as Chol−PEG−PpIX) that forms micelles in aqueous solutions. The Chol−PEG−PpIX with two hydrophobic units (cholesterol and PpIX) showed robust binding to plasma membranes and enabled significant cellular uptake via two pathways: (1) cholesterol moiety triggered the lipid raft-mediated endocytosis of Chol−PEG−PpIX with minimized endo/lysosomal trafficking after internalization; (2) the membrane-bound PpIX acted as a light-controlled trigger and can augment the permeability of plasma membranes upon laser irradiation, allowing the rapid influx of extracellular Chol−PEG−PpIX within 5 min. For systemic drug delivery, Chol−PEG−PpIX was anchored on the surface of liposomes via in situ membrane modification, which substantially avoided nonspecific binding of Chol−PEG−PpIX to red blood cells during circulation. Besides, the Chol−PEG−PpIX-anchored liposomes exhibited enhanced in vivo fluorescence , reduced liver uptake, prolonged tumor retention, and effective tumor ablation by photodynamic therapy . This work illustrates a new strategy for direct and efficient cytosolic delivery of photosensitizers, which may hold great promise in cancer therapy.
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PubMed
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.
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RSC Advances
·
2016
·Vol. 6
·期 63
·58218-58225
·
IF 3.289
Henmei Ni,Junxiu Liu,Kai Shi,Min Wu,Yadong Yang,Lijuan Zhang
The reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization of methyl methacrylate (MMA) was carried out in ethanol using polymethacrylic acid (PMAA)–4-cyanopentanoic acid dithiobenzoate (CADB) (degree of polymerization = 30, 122 and 450) as a macro chain transfer agent (CTA) and 2,2′-azobis(2,4-diemthyl valeronitrile) (V-65) as an initiator. In contrast to the random copolymerization systems, a dramatic increase of conductivity during the initial stage of RAFT polymerization was observed. It was confirmed that the conductivity resulted from the charged solvophobic blocks of soluble diblock copolymers, strongly dependent on the chain length of PMAA-CTA and PMMA. Objects of PMAA-b-PMMA were prepared by three methods, i.e. the polymerization-, temperature- and ion-induced self-assembly. The procedure of self-assembly commonly resulted in a dramatic decrease of conductivity. All results indicated that the electrostatic interaction played a role in the process of self-assembly, rather than just the solvophobic interaction of PMMA blocks in ethanol.
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高影响因子
CHINESE CHEMICAL LETTERS
·
2016
·
IF 1.947
Zhi-Wei Yu,Shu-Xi Gao,Kai Xu,You-Xiong Zhang,Jun Peng,Ming-Cai Chen
Organic/inorganic hybrid polymers have been widely studied for their potential use in nanocontainers and nanocarriers. In this article, one star-shaped hybrid polymer, polyhedral oligomeric silsesquioxane (POSS) grafted poly( N , N -(dimethylamino)ethyl methacrylate) (POSS- g -PDMA), was synthesized via reversible addition-fragmentation chain transfer polymerization (RAFT). The pH stimuli-responsive character of POSS- g -PDMA in aqueous solution were also studied.
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高影响因子
RSC Advances
·
2015
·Vol. 5
·期 30
·23683-23690
·
IF 3.84
Zhiwei Yu,Kai Xu,Zien Fu,Xin Liu,Youxiong Zhang,Jun Peng,Mingcai Chen
We designed and synthesized a series of amphiphilic copolymers from poly(ethylene glycol) monoacrylate (PEGMA), 2-(dimethylamino) ethyl methacrylate (DMAEMA), styrene (St), and butyl acrylate (BA) via reversible addition–fragmentation chain transfer (RAFT) polymerization. The dispersion capability of carbon nanofibers (CNFs) by these copolymers as well as their stability were investigated using UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), transmission electron microscopy (TEM) and dynamic light-scattering (DLS) techniques. The results show that both of the block copolymers PPEGMA-b-P(DMAEMA-co-St-co-BA) and PDMAEMA-b-P(PEGMA-co-PSt-co-PBA) enabled better efficiencies toward dispersion and functionalization of CNFs compared to the random copolymer and P(PEGMA-co-BA)-b-P(DMAEMA-co-St) polymer, which allowed us to evaluate the effect of block sequences on the dispersing properties and understand the structure–property relationship between CNFs and amino-containing block-copolymers.
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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.
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ENERGY & FUELS
·
2025
·
IF 5.3
Xiaoyu Lin,Gaojie Shi,Wenbin Ding,Bochao Yan,Suping Zhang
The rational modification and assembly of catalysts with regulable active sites for selective conversion of lignin to phenolic monomers remain challenging. In this work, a new modified spinel catalyst (NixCo3–xO4–Mo2C) is proposed for the selective production of phenolic monomers from Kraft lignin. The performance of the catalysts is greatly improved by the synergistic effect on Mo2C and NixCo3–xO4 spinel. The NiCo2O4–Mo2C catalyst achieved an outstanding catalytic conversion (up to 86.2 wt %) for the Kraft lignin depolymerization and excellent selective cleavage for phenolic monomers to 34.9 wt %. The characterization of the catalyst shows that Mo2C provided more acidic sites and improved the hydrogenation performance by changing the arrangement of spinel. Additionally, the hydrogenolysis of lignin model compounds further confirmed the outstanding performance of the modified spinel catalysts.
研究领域:
化学工程
·
催化材料科学
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高影响因子
Polymer Chemistry
·
2014
·Vol. 6
·期 7
·1127-1136
·
IF 5.368
Shangfeng Wang,Bin Wu,Feng Liu,Yun Gao,Weian Zhang
We herein report a new strategy to fabricate novel well-defined alternating copolymers of poly(VBCDEG-alt-SaAEMI)s which were synthesized via alternating RAFT copolymerization of para-methoxydiethylene glycol-substituted styrenes (VBCDEG) and N-(2-salicylaldehyde-aminoethyl)maleimides (SaAEMI). 1H NMR, 13C NMR, FTIR and GPC results indicate that poly(VBCDEG-alt-SaAEMI) copolymers have well-defined alternating structures and narrow polydispersity (Mw/Mn < 1.35). It is interesting that poly(VBCDEG-alt-SaAEMI) alternating copolymers exhibit an excellent selective fluorescence “OFF–ON” response to Zn2+ by inhibiting the photoinduced electron transfer (PET) effect through copolymerization, while the monomer SaAEMI almost has no fluorescence response to Zn2+ due to the PET process. The sensors based on poly(VBCDEG-alt-SaAEMI) alternating copolymers have very fast response (30 s) to Zn2+, 62-fold fluorescence enhancement in aqueous solution and a detection limit of about 0.25 μM. Additionally, the poly(VBCDEG-alt-SaAEMI) alternating copolymers also show a remarkable green fluorescence “OFF–ON” switch (230∼fold) when the pH turns from 11 to 12, thus these copolymers have potential application in dual-color detection.
研究领域:
材料化学
·
分析化学
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