Heliyon
·
2023
·
IF 4
Yuanyuan An,Cuifang Lu,Mengmeng You,Xinshuo Liu,Wenqiang Yao,Yitao Li
Prior to crosslinking and vulcanization, fluorosilicone rubber is a linear polymer. This linear polymer contains 3,3,3,-trifluoropropyl methyl siloxane links, a few methyl vinyl siloxane links, and is formed by co-polymerization of 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl) cyclotrisiloxane (D 3 F) with 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V 4 ) under alkaline conditions. To improve the performance of fluorosilicone rubber, three key points should be considered during the synthesis of vinyl-containing high-molecular-weight linear fluorosilicone polymers (fluorosilicone raw rubber): first, avoid the generation of low molecular weight equilibrium by-products; second, eliminate the influence of impurities; and third, increase the copolymerization participation rate of monomer V 4 . From the three aspects above, this study optimized the reaction conditions for the synthesis of high-molecular-weight linear fluorosilicone polymers containing vinyl. Various factors influencing polymerization were thoroughly investigated. These factors include the initiation system, accelerator, equilibrium reaction, feeding ratio, feeding sequence, neutralization mode, impurity content, etc.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2024
·
IF 4.9
Huigui Yang,Lihan Wang,Juan Xu,Li Lin,Yi Liu,Weigang Cui,Yunfei Zhi,Shaoyun Shan,Yingju Miao
Sulfur dioxide (SO 2 ) is one of the primary air pollutants, and its reaction with epoxides to produce sulfur-containing polymers is an efficient means of resource utilization for SO 2 , however, catalysts play a crucial role in this reaction. Polymeric ionic liquids (PILs) have become a hot topic in catalysis research due to their dual characteristics of ionic liquids and polymers. Therefore, a series of heterogeneous PILs were prepared, characterized, and employed for the copolymerization of SO 2 with epoxides in this study. The impact of different halide anions and hydrogen bond donors on catalytic performance was investigated. Optimal reaction conditions for copolymerization were determined by examining reaction temperature, reaction time, molar ratio of catalyst to epoxide, and other factors. Furthermore, PILs demonstrated recyclability for more than 6 cycles without a significant decrease in catalytic activity, and PILs exhibited broad applicability to various epoxides. Finally, density functional theory (DFT) calculations were employed to further elucidate the activation effect of halide anions and hydrogen bond donors on epoxides to propose a potential mechanism for the copolymerization of SO 2 with epoxides catalyzed by PILs.
研究领域:
化学
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF THE CHINESE CHEMICAL SOCIETY
·
2020
·Vol. 67
·期 10
·1818-1826
·
IF 1.554
Yang Hu,Longchao Du,Cun Li,Jiale Shen,Weiju Zhu,Chenxi Shao
Carbon dioxide (CO 2 ) is an easily available renewable carbon source that can be used as a comonomer in the catalytic ring-opening polymerization of epoxides to form aliphatic polycarbonates. Herein, a series of new Salen-Co(III) bifunctional catalysts were synthesized for the first time, and they were studied to catalyze the copolymerization of CO 2 and propylene oxide (PO)/cyclohexene oxide (CHO). At the same time, the effects of reaction conditions (electronic effect, temperature, time) on catalytic activity and selectivity were investigated. The results show that the Salen-Co(III) complexes with electron-withdrawing groups have higher selectivity and activity for propylene carbonate (PPC)/cyclohexylene carbonate (PCHC). At the same time, the Salen-Co(III) complexes can better catalyze the copolymerization of CHO and CO 2 than that of PO and CO 2 . The catalytic efficiency of the four complexes increased with increasing temperature, and the best reaction condition is 80°C, 30 min and 2 MPa of CO 2 .
研究领域:
化学催化
·
材料科学
✓ 已验证
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2014
·
IF 4.086
Shuaiyuan Han,Baohua Yue,Liuming Yan
The poly(vinylphosphonic acid) (PVPA), poly(4-(α-methyl)vinyl-1 H -1,2,3-triazole) (PMVTri), and poly(VPA- co -MVTri) were synthesized, and proton exchange membranes were prepared based on the acid-base polymeric composite of PVPA and PMVTri, and acid-base amphoteric copolymer of poly(VPA- co -MVTri). The overall performances of PVPA, proton conductivity, thermal and oxidative stability, and water resistance, are greatly improved by compositing of PMVTri or copolymerization with 4-(α-methyl)vinyl-1 H -1,2,3-triazole (MVTri). About four or eight folds improvement in maximum proton conductivity was observed in the polymeric composite of PVPA/PMVTri or acid-base amphoteric copolymer poly(VPA- co -MVTri) because of the redistribution of ions in the heterostructures of PVPA and PMVTri, respectively, compared with the pristine PVPA. At the same time, the oxidative stability and the water resistance of PVPA were also greatly improved attributing to the absent of α-H in the main chain of PMVTri and the acid-base interaction between the phosphonic acid groups and the triazolyl groups, respectively.
研究领域:
材料科学
·
高分子化学
·
电化学
·
膜技术
✓ 已验证
DOI
高影响因子
Polymer Chemistry
·
2024
·Vol. 15
·期 21
·2148-2156
·
IF 4.1
Xiao-Yu Zhang,Hao-Liang Li,Bo Xiang,Xiang-Wei Liu,Shu Zhang,Yi-Xian Wu
A series of imidazolidin-2-iminato vanadium complexes VOCl2[1,3-R2-(CH2N)2CN], Vi1, R = 2,6-Me2C6H3; Vi2, 2,4,6-Me3C6H2; Vi3, R = 2,6-iPr2C6H3; Vi4, R = cyclohexanyl, were synthesized and fully characterized by NMR (1H, 13C and 51V) and elemental analysis. The copolymerizations of ethylene with propylene using the imidazolidin-2-iminato vanadium complexes were conducted in the presence of Et3Al2Cl3. The catalytic activity increased in the order of Vi4 < Vi1 < Vi2 < Vi3, probably due to the different electron donating natures of the imidazolidin-2-iminato ligands. Both high catalytic activity of 2.44 × 106 g copolymer per mol of V per h and incorporation ratio of propylene (up to 32.5 mol%) were afforded by using the Vi3/Et3Al2Cl3 catalytic system in the copolymerization of ethylene with propylene. An ethylene–propylene copolymer with ultra-high molecular weight (Mw = 2660 kg mol−1) could be also synthesized by using the Vi3/Et3Al2Cl3 catalytic system. Importantly, the highly efficient terpolymerizations of ethylene, propylene with 5-ethylidene-2-norbornene (ENB) were also achieved by using this catalytic system, affording ethylene–propylene–ENB terpolymers (EPDMs) with high contents of ENB units up to 9.8 mol% (29.8 wt%) and ultra-high molecular weight (Mw = 1521–2537 kg mol−1). This work offers a unique catalytic system of vanadium complexes for the synthesis of EPDM with both high content of ENB units and ultra-high molecular weight.
研究领域:
聚合物化学
·
材料科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）