ACS Applied Materials & Interfaces
·
2011
·
IF 2.925
Lei Wang,Ke Zeng,Sixun Zheng
Hepta(3,3,3-trifluoropropyl) polyhedral oligomeric silsesquioxane (POSS)-capped poly(N-isopropylacrylamide) (PNIPAAm) telechelics with variable lengths of PNIPAAm midblocks were synthesized by the combination of reversible addition−fragmentation chain transfer polymerization (RAFT) and the copper-catalyzed Huisgen 1,3-cycloaddition (i.e., click chemistry). The POSS-capped trithiocarbonate was synthesized and used as the chain transfer agent for the RAFT polymerization of N-isopropylacrylamide. The organic−inorganic amphiphilic telechelics were characterized by means of nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). Atomic force microscopy (AFM) shows that all the POSS-capped PNIPAAm telechelics exhibited microphase-separated morphologies, in which the POSS terminal groups were self-assembled into the microdomains and dispersed into the continuous PNIPAAm matrices. The POSS nanodomains could behave as the physical cross-linking sites and as a result the physical hydrogels were formed while these POSS-capped PNIPAAm telechelics were subjected to the solubility tests with water. These physical hydrogels possessed well-defined volume phase transition phenomena and displayed rapid reswelling and deswelling thermoresponsive behavior compared to control PNIPAAm hydrogel.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
PubMed
高影响因子
MACROMOLECULES
·
2015
·
IF 5.8
Zefeng Song,Ke Wang,Chengqiang Gao,Shuang Wang,Wangqing Zhang
A new multi-stimuli-responsive homopolymer of poly[N-[2-(diethylamino)ethyl]acrylamide] (PDEAEAM), which combines the thermoresponsive and pH/CO2-responsive moieties of the diethylamino and acrylamide groups, was proposed and synthesized by RAFT polymerization. Well-defined PDEAEAM was synthesized by solution RAFT polymerization as indicated by the linear increase in the polymer molecular weight with the monomer conversion and the narrow molecular weight distribution. The appending diethylamino group in the polymer backbone was found to be crucial to determine the thermoresponse of PDEAEAM in water. The parameters including the polymerization degree, the polymer concentration, the deuterated solvent, the terminal attached on the polymer backbone, the additives of salt and urea, and pH and bubbling CO2 affecting the thermoresponse of PDEAEAM in aqueous solution at the lower critical solution temperature (LCST) were investigated. The temperature-variable 1H NMR analysis suggests that the dehydration of PDEAEAM at temperature above LCST is ascribed to the weakened hydrogen bonding between the CONHCH2 and/or (CH2N(CH2CH3)2) moieties with the solvent of water. The proposed multi-stimuli-responsive homopolymer of PDEAEAM has two advantages of (1) the convenient and controllable RAFT synthesis and (2) the pH/CO2 tunable LCST at ∼36 °C being very close to body temperature.
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
·
2023
·Vol. 30
·期 4
·1-8
·
IF 2.8
Li Dongxiang,Qian Xing,Huang Rui,Li Chunfang
Thermo-responsive poly( N -isopropylacrylamide) with terminal azobenzene group (PNIPAM-Azo) can show distinct property changes in response to temperature and light. In this paper, azobenzene-terminated trithiocarbonate (DDMAT-Azo) was synthesized as chain transfer agent, with which PNIPAM-Azo was prepared by reversible addition-fragmentation transfer (RAFT) polymerization of NIPAM in 1, 4-dioxane at 80 °C under N 2 atmosphere, azodiisobutyronitrile as initiator. The structure of DDMAT-Azo was characterized by nuclear magnetic resonance (NMR) and fourier transform infrared spectra, and PNIPAM-Azo was characterized by NMR spectra and Gel Permeation Chromatography (GPC). The result from GPC showed the numerical average molecular weight of PNIPAM-Azo was 3870 and its molecular weight distribution index was 1.31. Furthermore, thermo- and light-responsive hydrogel was obtained by introducing PNIPAM-Azo. Both PNIPAM-Azo and the hydrogel showed good light sensitivity and thermo sensitivity. Such double-stimuli sensitive hydrogel will be applied in biomaterials such as sensor, drug controlled release, information storage etc.
研究领域:
高分子化学
·
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
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.
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
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
EUROPEAN POLYMER JOURNAL
·
2021
·
IF 4.598
Suyan He,Li Xiao,Luminita Marin,Yike Bai,Xinjian Cheng
The development of water-soluble polymer dyes is of great practical and scientific significance. In this article, small fluorescent molecule boron-dipyrromethene (BODIPY) bearing C=C bond was synthesized first. And then, via Suzuki reaction, recognition groups were introduced into the 2, 6 positions of BODIPY. Thus polymerizable fluorescent monomers were prepared. Finally, methacrylic acid (MAA) was copolymerized with the as-prepared small molecular fluorescent monomers via reversible addition-fragmentation chain transfer (RAFT) polymerization methodology. Four fully-water-soluble polymer sensors with BODIPY moieties in the end of the polymer chain were obtained eventually. In the presence of long PMAA chain, and by the assistance of it, BODIPY could be dissolved totally in water. These polymer sensors exhibited sensitive and selective recognition ability to Fe 3+ . Even the content rate of BODIPY was as low as 0.5% of the polymer (calculated from element analysis), the detection limit could reach 1.2 μM. The sensors with two recognition groups in one BODIPY unit were more sensitive than that with one recognition groups in each BODIPY unit. The sensing mechanism was investigated as well. By endowing the water solubility to organic sensors, the application scope could be greatly enlarged in sensing metal ions in aqueous environments. This work provides a method to develop water soluble high performance polymer sensors.
研究领域:
材料科学
·
化学传感器
·
分析化学
✓ 已验证
产品关联
DOI
高影响因子
Polymer Chemistry
·
2024
·Vol. 15
·期 27
·2780-2789
·
IF 4.1
Ke Wang,Zilong Wang,Meiyu Si,Xiaofang Liu,Guiyan Liu,Yongfei Zeng
Three novel temperature/pH/CO2-triple-responsive homopolymers namely P(Et-N-EO2MA), P(THP-N-EO2MA) and P(Ph-N-EO2MA) were prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization. They have the same backbone structure but different types of end substituents i.e., ethyl, tetrahydropyran, and the benzene ring, respectively. Subsequently, their responsive properties were studied. P(Et-N-EO2MA) has a lower critical solution temperature (LCST)-type cloud point (CP) in aqueous solution and is affected by many factors such as the molecular structure and weight, concentration, additives, pH and CO2. P(THP-N-EO2MA) is soluble in water, but in different buffer solutions, it shows a soluble–LCST–insoluble transition, and its LCST-type CP can also be adjusted by molecular weight and concentration. P(Ph-N-EO2MA) is insoluble in water, but reversible phase transformation can be achieved by adjusting the pH of the solution or injecting CO2, and it also shows different properties in buffer solutions and an upper critical solution temperature (UCST)-type CP in n-butanol. In addition, since P(Ph-N-EO2MA) is amphiphilic, it can be self-assembled in solution, and the release of Nile Red (NR) can be achieved under the stimulation of acid. The different properties of these homopolymers show the effect of substituents on the responsiveness of multistimuli-responsive polymers, which provides ideas for the design of stimuli-responsive polymers, and have good application prospects in the fields of self-assembly and controlled release.
研究领域:
高分子化学
·
材料科学
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2019
·
IF 3.375
Jie Jiang,Wen-Jun Wang,Bo-Geng Li,Shiping Zhu
The tactics of targeting copolymer composition (CC) and molecular weight (MW) via semibatch controlled radical polymerization (CRP) have been extensively studied. However, little effort is made to target copolymer sequence length (CSL) and its triad sequence, which are among the key microstructures determining material properties of the copolymers. This work presents a method to design and synthesize targeted CSL and copolymer triads in a reversible addition–fragmentation chain transfer radical mini-emulsion copolymerization system (RAFT) through a semibatch chain and sequence model coupled with Alfrey Mayo model. The kinetic model was first derived and correlated with experimental results of the batch St/BA copolymerizations. The semibatch RAFT model was then employed to calculate the feed-rate to target CSL and their triads. St/BA copolymers with different uniform CSLs and their triads are synthesized through the programmed semibatch RAFT mini-emulsion copolymerization processes.
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
MOLECULES
·
2022
·Vol. 27
·期 10
·3214
·
IF 4.927
Yi Gao,Xuesong Yao,Qinggeng Jiang,Jianhe Liao,Yongping Chen,Rentong Yu
Microgels have unique and versatile properties allowing their use in forward osmosis areas as a draw agent. In this contribution, poly(4-vinylpyridine) (P4VP) was synthesized via RAFT polymerization and then grafted to a poly(N-Isopropylacrylamide) (PNIPAAm) crosslinking network by reverse suspension polymerization. P4VP was successfully obtained by the quasiliving polymerization with the result of nuclear magnetic resonance and gel permeation chromatography characterization. The particle size and particle size distribution of the PNIPAAm-g-P4VP microgels containing 0, 5, 10, 15 and 20 wt% P4VP were measured by means of a laser particle size analyzer. It was found that all the microgels were of micrometer scale and the particle size was increased with the P4VP load. Inter/intra-molecular-specific interactions, i.e., hydrogen bond interactions were then investigated by Fourier infrared spectroscopy. In addition, the water flux measurements showed that all the PNIPAAm-g-P4VP microgels can draw water more effectively than a blank PNIPAAm microgel. For the copolymer microgel incorporating 20 wt% P4VP, the water flux was measured to be 7.48 L∙m−2∙h−1.Keywords:microgel;forward osmosis;draw agent;P4VP
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
CARBOHYDRATE POLYMERS
·
2018
·
IF 5.158
Wenyan Wang,Yuanyuan Yu,Ping Wang,Qiang Wang,Yongqiang Li,Jiugang Yuan,Xuerong Fan
This study reports on eco-friendly graft polymerization approach for the modification of a cellulosic material via combination between enzymatic catalysis and reversible addition-fragmentation chain transfer polymerization (RAFT). Polyacrylamide (PAM) was polymerized on a cellulosic filter paper via horseradish peroxidase (HRP)-initiated RAFT polymerization. The results of grafting ratio, conversion, and pseudo-first-order kinetics were proved that the PAM graft polymerization on the filter paper followed RAFT rules. The results of Attenuated total reflection (ATR-FTIR), elemental analysis, and X-ray photoelectron spectroscopy (XPS) confirmed the presence of PAM in PAM-grafted filter paper. The results of water contact angle and Thermogravimetric analysis (TG) evidenced the change in the wetting properties and thermal performance, respectively of the treated filter paper. This work provides a new environmentally approach to graft polymerization on cellulosic materials.
研究领域:
材料科学
·
生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Polymers
·
2017
·Vol. 9
·期 12
·681
·
IF 3.364
Jianbo Tan,Xueliang Li,Jun He,Qin Xu,Yuxuan Zhang,Xiaocong Dai,Liangliang Yu,Ruiming Zeng,Li Zhang
Herein, we report a photoinitiated reversible addition-fragmentation chain transfer (RAFT) dispersion copolymerization of methyl methacrylate (MMA) and methyl methacrylic (MAA) for the preparation of highly monodisperse carboxyl-functionalized polymeric microspheres. High rates of polymerization were observed, with more than 90% particle yields being achieved within 3 h of UV irradiation. Effects of reaction parameters (e.g., MAA concentration, RAFT agent concentration, photoinitiator concentration, and solvent composition) were studied in detail, and highly monodisperse polymeric microspheres were obtained in most cases. Finally, silver (Ag) composite microspheres were prepared by in situ reduction of AgNO3using the carboxyl-functionalized polymeric microspheres as the template. The obtained Ag composite microspheres were able to catalyze the reduction of methylene blue (MB) with NaBH4as a reductant.Keywords:carboxyl-functionalized microspheres;RAFT polymerization;photoinitiated dispersion polymerization
研究领域:
材料科学
·
高分子化学
✓ 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）