POLYMER
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2021
·
IF 4.43
Liang Xiang,Min Qiu,Minjing Shang,Yuanhai Su
With the RAFT arm-first method, butyl acrylate and 4-acryloylmorpholine were used as monomers to form linear arms, which subsequently reacted with the cross-linker 1,6-hexanediol diacrylate to form star-shaped macromolecules in cascade microreactor systems. After studying polymerization kinetics in each step, homoarm and miktoarm star products with various arm compositions were steadily prepared by optimizing the reaction flowsheet and adjusting the reactant formula. Such continuous-flow processing avoided tedious intermediate purification procedures and prepared polymer products with considerable star yield (>70%), molecular weights ( M w,LS > 100 kg/mol) and arm numbers (>30). Multiple emulsions (including two types, i.e., oil-in-water and water-in-oil) were formed utilizing star products with different amphiphilic architectures as emulsifiers . This study demonstrated that in this continuous-flow mode, through regulating the residence time and flow rate ratio in each step, the arm and core structures of star polymers were tailored to possess remarkable functional applications.
研究领域:
高分子化学
·
材料科学
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DOI
高影响因子
REACTIVE & FUNCTIONAL POLYMERS
·
2009
·
IF 2.039
Li-Ping Wang,Li-Min Zhao,Wen-Zhi Li
The design of a novel rare earth optical-functional hybrid material based on reversible addition-fragmentation chain transfer (RAFT) polymerization was detailed. The hydroxyl groups on the silica hollow sphere surface were converted into trithiocarbonate chain transfer agents (CTA), and were further used to mediate the RAFT polymerization of methyl methacrylate (MMA). Hollow sphere-g-poly(methyl methacrylate)-block-terbium (HS-g-PMMA-b-Tb) optical-functional hybrid materials were obtained by grafting the Tb complex to the end of the PMMA chains via RAFT polymerization. The samples were characterized by XPS , FT-IR, TGA and SEM respectively. The results indicated that the MMA had grafted from the surface of the hollow sphere successfully and the average diameter of the hollow spheres was about 1.1 μm. The fluorescence properties of the HS-g-PMMA-b-Tb hybrid materials were also investigated.
研究领域:
材料科学
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光学材料
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产品关联
DOI
高影响因子
JOURNAL OF MATERIALS IN CIVIL ENGINEERING
·
2024
·Vol. 36
·期 8
·04024208
·
IF 3.1
Xiaodong Chen,Xinde Tang,Cuizhen Zhang,Haichao Guo,Xuefan Li,Laixue Pang,Yong Yang,Fuying Dong
Comblike polycarboxylate superplasticizers (PCs) have been widely used as construction and building materials by means of high fluidity and fine dispersibility via electrostatic repulsion and steric hindrance. The conventional PCs are usually synthesized by free radical polymerization, which limit to understand and even distort the structure-property relationship due to the random molecular structure and the broad polydispersity. In this work, polycarboxylate ether superplasticizers of acrylic acid (AA) and ethylene glycol monovinyl PEG (EPEG) with controlled structure were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization. The resultant copolymers (denoted as EPCs) were characterized by FT-IR, 1H NMR and GPC spectroscopy. The effect of actual acid/ether (AA/EPEG) ratio on the adsorption capacity and dispersion ability of EPCs in cement paste were deeply investigated. These results demonstrate that the dispersibility of EPCs with controlled molecular weights and comparatively narrow polydispersity indexes (PDI=1.2–1.4) strongly depends on the acid/ether ratio. With an increase of the feed molar ratio of AA/EPEG from 4∶1 to 8∶1, the molecular weight and their distribution of EPCs increases accordingly. In addition, the adsorption capacity and dispersion property of EPCs to cement are densely related to the molecular structure and composition and superior to that of conventional PC analogues. A possible mechanism was proposed that EPCs can act uniformly on the surface of cement particles due to the well-defined molecular structure and well-distributed molecular weight, which is different from the conventional PCs, which will offer the fundamentals of design and synthesis for polycarboxylate superplasticizers with controlled structures.
研究领域:
建筑材料化学
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高分子化学
✓ 已验证
DOI
高影响因子
MOLECULES
·
2017
·Vol. 22
·期 2
·152
·
IF 2.861
Jiachen Ma,Luqing Zhang,Bing Geng,Umair Azhar,Anhou Xu,Shuxiang Zhang
In this work, a thermo-responsive and cross-linked fluoropolymer poly(2,2,2-Trifluoroethyl) methacrylate (PTFEMA) was successfully prepared by reversible addition-fragmentation chain transfer (RAFT) mediated aqueous polymerization with a thermo-responsive diblock poly(dimethylacrylamide-b-N-isopropylacrylamide) (PDMA-b-PNIPAM) that performed a dual function as both a nanoreactor and macro-RAFT agent. The cross-linked polymer particles proved to be in a spherical-like structure of about 50 nm in diameter and with a relatively narrow particle size distribution.1H-NMR and19F-NMR spectra showed that thermo-responsive diblock P(DMA-b-NIPAM) and cross-linked PTFEMA particles were successfully synthesized. Influence of the amount of ammonium persulfate (APS), the molar ratio of monomers to RAFT agent, influence of the amount of cross-linker on aqueous polymerization and thermo-responsive characterization of the particles are investigated. Monomer conversion increased from 44% to 94% with increasing the molar ratio of APS and P(DMA-b-NIPAM) from 1:9 to1:3. As the reaction proceeded, the particle size increased from 29 to 49 nm due to the consumption of TFEMA monomer. The size of cross-linked nanoparticles sharply decreased from 50.3 to 40.5 nm over the temperature range 14–44 °C, suggesting good temperature sensitivity for these nanoparticles.Keywords:RAFT polymerization;nanoreactor;aqueous polymerization;cross-linking;temperature sensitivity
研究领域:
材料科学
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高分子化学
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产品关联
DOI
PubMed
高影响因子
Journal of Water Process Engineering
·
2024
·
IF 6.3
Mengyuan Nie,Jian Zhang,Xiujun Wang,Bo Huang,Ming Duan
With the development of oilfields, the liquid volume of oily wastewater gets larger. Thus, more efficient flotation agents must be developed. In this regard, cationic polyacrylates with amphiphilic structures are potentially efficient flotation agents. Many studies have explored the effect of monomer type on flotation performance. However, there is a lack of investigations on the effect of block sequences on flotation performance. In this paper, acrylates (including methyl acrylate (MA) and ethyl acrylate (EA)) and cationic monomers (including acryloxyethyl trimethyl ammonium chloride (DAC), methylacryloxyethyl trimethyl ammonium chloride (DMC) and acryloxyethyl benzyl dimethyl ammonium chloride (DBC)) were used as raw materials, random, diblock and triblock copolymers were prepared through free radical polymerization and reversible addition-fragmentation chain transfer (RAFT) polymerization. The effect of the copolymer sequence on flotation performance was studied, and triblock copolymer P(DBC-b-MA-b-DBC) had better flotation performance than those of other copolymers. The synthesis conditions of P(DBC-b-MA-b-DBC) were successively optimized using the single-factor and response surface methods, and the optimal synthesis conditions were obtained as follows: monomer concentration of 51 wt%, the first section m(DBC): the second section m(MA): the third section m(DBC) = 1.5:1:1.5, initiator concentration of 0.28 wt%, reaction time of each section of 2 h, and reaction temperature of 73 °C. Under flotation temperature of 25 °C, P(DBC-b-MA-b-DBC) concentration of 70 mg/L, aeration flow rate of 2.0 L/min and flotation time of 10 min, the oil removal of oily wastewater with initial oil content of 822 mg/L reached 96.5 %. The results of the study can provide reference for the research and development of oily wastewater treatment agents.
研究领域:
环境科学
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高分子化学
✓ 已验证
产品关联
DOI
高影响因子
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.
研究领域:
材料科学
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高分子化学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2022
·
IF 4.326
Fenping Wang,Jiawei Li,Lin Lu,Xiaofei Yan,Ziwen Xie,Dongming Qi
Reversible addition–fragmentation chain transfer (RAFT) emulsion polymerization is a powerful tool for polymer encapsulation of pigment nanohybrids. Conventional RAFT emulsion polymers, however, contain sulfur residues that contribute to undesired odor and deleterious effects on final materials. Our strategy relies on an amphiphilic macromonomer poly(methacrylic acid-co-methyl methacrylate) P(MAA-co-MMA) with an ω-unsaturated end group synthesized in situ via cobalt(II)-mediated catalytic chain transfer polymerization (CCTP) at the surface of C.I. Pigment Blue 15:3 (PB) particles. Subsequently, these macromonomers are used as the living points to mediate the in situ sulfur-free RAFT (SF-RAFT) emulsion polymerization of monomers (butyl methacrylate (BMA) and butyl acrylate (BA)). It was found that a well-controlled polymerization process was achieved by semibatch SF-RAFT emulsion polymerization on the PB surface, as evidenced by the smooth increase in the molecular weight of polymer chains as the polymerization progressed and by transmission electron microscopy (TEM) results. Due to the sealing effect, these polymer/PB hybrid particles exhibited excellent colloidal stability in the aqueous phase. More importantly, film-forming hybrid particles with a soft P(BMA-co-BA) shell were successfully prepared in this work, which suggested that SF-RAFT-mediated polymerization may offer a useful alternative approach to traditional RAFT emulsion polymers for the preparation of organic/inorganic nanohybrids.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
CARBOHYDRATE POLYMERS
·
2020
·
IF 7.182
Xuanang Gong,Zenghui Cheng,Shishuai Gao,Daihui Zhang,Yufeng Ma,Jifu Wang,Chunpeng Wang,Fuxiang Chu
In this work, reversible addition-fragmentation chain transfer (RAFT) polymerization and Schiff base chemistry was combined to fabricate self-healing adhesives. An esterification reaction was first performed to prepare ethyl cellulose based macroinitiators. Then, a “grafting from” RAFT of vanillin methacrylate and lauryl methacrylate was used to obtain graft copolymers. DSC result showed that the glass transition temperature was manipulated via changing the ratio of vanillin and fatty acids moieties. NMR spectrum analysis demonstrated the presence of aldehyde groups, which were available for the dynamic crosslinking to generate a network as self-healing adhesives. The adhesive test showed that the shear strength could reach 0.81 MPa with a self-healing efficiency of 98.7 %. The bottlebrush structures of copolymers and reversibility of Schiff base chemistry might collaboratively contribute to the high self-healing efficiency. This study provides a facile way to fabricate high-performance self-healing adhesives from ethyl cellulose and renewable resources.
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
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
·
2018
·Vol. 56
·期 18
·2072-2079
·
IF 2.588
Qian Yang,Xianhong Zhang,Yuhong Ma,Dong Chen,Wantai Yang
A photoinduced electron transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization of p -methylstyrene ( p -MS) and styrene (St) with 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid as the chain transfer agent (CTA) and aromatic aldehydes, including 4-cyanobenzaldehyde (PC1), 2,4-dimethoxy benzaldehyde, and 4-methoxy benzaldehyde, as organic photocatalysts has been demonstrated via irradiation with 23 W compact fluorescent lamps. The kinetics of the polymerizations shows first order with respect to monomer conversions. Linear evolution of the M n of the produced polymers with the monomer conversion is observed. Meanwhile, the as-prepared polymers are of relatively narrow polydispersity (PDI = M w / M n ). For instance, the polymerization of p -MS shows living polymerization features using PC1 within a range of solvents. Especially, the M n of P p MS increased from about 2100 to 12,700 g/mol with the monomer conversion from 8% to 52% in tetrahydrofuran. The controlled polymerization of St is also observed under optimal reaction conditions. However, the M n discrepancy between the experimental readings and theoretical calculations is greater at the monomer conversions greater than 40% and the PDI increased gradually over the monomer conversion. This is probably because that CTA is strongly sensitive to the light irradiation with wave range around its characteristic absorption wavelength, leading to significant decomposition of CTA moieties during the RAFT polymerization. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56 , 2072–2079
研究领域:
高分子化学
·
材料科学
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产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2015
·Vol. 133
·期 5
·
IF 1.768
Guangfa Zhang,Qinghua Zhang,Qiongyan Wang,Xiaoli Zhan,Fengqiu Chen
A series of gradient fluorinated copolymers with a broad variation of the monomer units in the polymer chain were synthesized via semibatch CPDB-mediated RAFT miniemulsion polymerization technique. In the presence of RAFT agent 2-cyanoprop-2-yl dithiobenzoate (CPDB), the copolymerization of BMA and FMA in miniemulsion exhibited typical features of a controlled molecular weights and narrow polydispersities. The macromolecular structure and thermal behavior of the synthesized fluorinated copolymers were investigated in detail. The DSC analyses show that the gradient copolymers showed a unique thermal behavior with broad range of transition temperature. It was also confirmed that the fluorinated gradient copolymer exhibited obvious surface segregation structure and ultra-low surface energy between 16.8 and 20.3 mN/m. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 42936.
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
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
Advanced Membranes
·
2023
·
IF 0
Mohammed Kamal Hadi,Liru Su,Yuan Li,Abdalazeez Ismail,Sambasivam Sangaraju,Fen Ran
Polyethersulfone (PES) polymers are useful for a variety of membranes' bio-related applications. However, due to its failure to satisfy certain performance and biocompatibility standards, PES requires further surface modification. Herein, we report a facile and flexible method of PES membrane modification by combining the synthesis of silicon oxide nanoparticles grafted with polyvinylpyrrolidone (PVP) as hydrophilic macromolecules via reversible addition fragmentation chain-transfer polymerization (RAFT) and aminated polyethersulfone. The blending of polyethersulfone-modified membranes with SiO 2 @PVP and aminated polyethersulfone results in a robust, hydrophilic, and biocompatible surface. This research work uniquely uses this strategy to stabilize the existence of the hydrophilic modifiers (SiO 2 @PVP and aminated polyethersulfone) within the membrane matrix. Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) are used to analyze the prepared polymer brush and the modified membranes. The modified membranes demonstrate high pure water flux at 345 L m −2 h −1 and bovine serum albumin (BSA) rejection at 98 %. The prepared membranes also show favorable hydrophilicity with a contact angle of 46.8° compared with pristine polyethersulfone at 79°. Furthermore, the modified membranes demonstrate an acceptable degree of blood biocompatibility according to partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), and fibrinogen (FIB) concentration analysis. Based on inductively coupled plasma optical emission spectroscopy (ICP-OES), the silicon nanoparticle leaching in permeate is in a safe range. Accordingly, the modified polyethersulfone membrane is safe and suitable for hemodialysis and bio-related applications.
研究领域:
高分子化学
·
纳米材料
·
生物医学工程
·
表面改性
·
膜科学
✓ 已验证
DOI
危险品化学品经营许可证（带存储）