共查询到16条相似文献,搜索用时 78 毫秒
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离子液体具有独特的理化性能,作为一种环境友好、"可设计性"的溶剂,近年来成为化学领域的热点和前沿。离子液体作为自由基聚合反应的溶剂,对聚合速率、聚合产物结构及性能都有一定的影响。离子液体已经被较为广泛地应用于不同介质、不同物相中的自由基聚合反应,但是并不完全。近两年来已有研究工作者将离子液体应用于微乳液和气相中的自由基聚合反应,并和其他有机溶剂及水溶液共同调控自由基聚合反应。离子液体也首次应用于有机碲调控的自由基聚合反应和氮氧稳定的自由基聚合反应。同时离子液体也可以调控自由基聚合反应后聚合物的结构和形貌,是一种很好的进行聚合物自组装的溶剂。本文主要综述了近年来离子液体对自由基聚合反应的影响,特别是对聚合产物结构及性能的影响,最后展望了离子液体在聚合反应中的应用前景。 相似文献
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介绍了室温离子液体在烯类单体自由基聚合反应中的主要应用,结合国内外研究现状和作者实际工作中的体会,提出了对今后发展趋势的看法。 相似文献
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在1-丁基-3-甲基咪唑四氟硼酸盐离子液体中以氯化苄为引发剂,氯化亚铜/2,2’-联吡啶为催化剂成功实现了丙烯酰胺的原子转移自由基聚合(ATRP)。用IR对聚合物的结构进行了表征,证实聚合物链端具有-Cl端基。考察了引发剂用量、催化剂和配体用量、单体用量和反应时间等因素对丙烯酰胺在离子液体中的原子转移自由基聚合的影响,结果表明,反应时间为1.5 h时转化率达到31.43%,MnGPC=4451,Mw/Mn=1.38。且80 ℃下丙烯酰胺在离子液体中的最佳聚合工艺条件为:单体浓度3 mol/L,引发剂浓度0.010 mol/L,催化剂浓度0.015 mol/L,反应时间1 h。 相似文献
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离子液体是一种有机盐,在接近室温下呈液状.离子液体是难挥发、极性高的溶剂,它能溶解很多种有机、无机和金属有机化合物.虽然有越来越多的人报道了有关离子液体在有机合成中的应用,但是在聚合过程中的应用却很少.然而在近几年,科学家证明了离子液体在聚合物的合成中的作用很大.在以离子液体为介质的自由基聚合反应中,kp/kt 会增大.尤其是在原子转移自由基聚合中,以离子液体作为溶剂有助于聚合物与残余催化剂的分离.本文主要阐述了原子转移自由基聚合反应的基本原理、特点以及离子液体在原子转移自由基聚合中的应用,并且还介绍了其他研究者的工作和原子转移自由基聚合的发展前景. 相似文献
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以季戊四醇为原料,合成了2,2-二溴甲基-1,3-二溴丙烷(PEBr4),并以此为四官能度引发剂,Cu0粉/三-(2-二甲氨基乙基)胺(Me6-TREN)为催化体系,在离子液体中实现了丙烯酰胺(AM)的单电子转移活性自由基聚合(SET-LRP),得到了窄分子量分布的星形聚丙烯酰胺(PAM),Mw/Mn约为1.26(MGPCn=14.1×103,转化率为43.4%)。 采用1H NMR对PAM结构进行表征确认,并采用GPC测定了PAM的分子量及分子量分布;考察了水、单体/催化剂(引发剂)配比对聚合反应的影响。 结果表明,少量水的加入能够加快聚合反应,使链增长速率常数由kappp=0.042 4 h-1增加至kappp=0.148 6 h-1;催化剂、引发剂用量越大,AM的SET-LRP的聚合反应速率越快,聚合反应的可控性越好,Mn随催化剂用量的增大及引发剂用量的减小而增大,且与理论分子量相近,分子量分布均呈下降趋势。 相似文献
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Veronika Strehmel 《Macromolecular Symposia》2007,254(1):25-33
Summary: Ionic liquids are efficient solvents for free radical homo- and copolymerization. Important parameters for selection of ionic liquids are their liquidus range, their viscosity, and their polarity. Viscosity of ionic liquids strongly influences the degree of polymerization of homopolymers. Micropolarity of ionic liquids can be used to explain differences in the composition of copolymers made on the basis of a relatively nonpolar methacrylate and a highly polar zwitterionic methacrylate. 相似文献
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Summary: The analysis of the influence of ionic liquids (ILs) in polymer synthesis as an alternative for common organic solvents is still an active field of research. 1 Using ILs as solvents for free radical polymerizations implies a significant increase in polymerization rates and molecular weights which can be observed. In this work we examined the copolymerization behaviour of styrene (S) and methyl methacrylate (MMA), glycidyl methacrylate (GMA) and 2-hydroxypropyl methacrylate (HPMA) with acrylonitrile (AN) in 1-etyhl-3-methylimidazolium ethylsulfate ([EMIM]EtSO4). ILs are liquids with comparable high polarities and viscosities. These two characteristic properties are strongly correlated with the rate coefficients of propagation kp and termination kt. 2 - 4 The rate constant of termination kt decreases when the IL concentration and therefore the viscosity of the reaction mixture is increased, whereas the propagation rate coefficient kp increases with increasing IL content. The viscosity of the IL can be varied by either working with mixtures of IL with conventional organic solvents – here the IL [EMIM]EtSO4 was mixed with DMF – or by variation of the temperature. The influence of the viscosity of the IL ([EMIM]EtSO4) on polymerization kinetics of methyl methacrylate (MMA) and styrene/acrylonitrile (S/AN) was investigated. 相似文献
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Free radical polymerization of acrylonitrile (AN) in ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]), 2,2;m1-azobisisobutyronitrile (AIBN) as initiator was investigated. Early investigations on polymerizations using ionic liquids indicate that they serve as especially good solvents to achieve high molecular weight polymers. Free radical polymerizations result in higher molecular weight polymers, for ionic liquids have low chain transfer constants and act to stabilize the active radical during the process of polymerization. The thermal stability of polymers synthesized in ionic liquids have be improved obviously than that in traditional solvents. 相似文献
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Assist. Prof. Dr. Shiori Suzuki Prof. Dr. Kenji Takahashi 《Chemical record (New York, N.Y.)》2023,23(8):e202200264
Ionic liquids (ILs) are the only media that can allow the homogeneous organocatalytic reactions of lignocellulosic biomass (lignocellulose), since the designability of their cations and anions offers the dual functions of solubility and catalytic activity. This review provides an account of our recent achievements in the organocatalytic approaches for converting lignocellulose into polymer materials based on the principles of IL design that we have originally established. These methodologies include the simple and mild chemical modification of cellulose and lignin under high conversions, with high selectivity, and/or with efficient atom economy. Similar reactions and subsequent fractionation processes are applied to lignocellulose, and a highly productive reaction system is developed using a twin-screw extruder that is specific to the IL media. 相似文献
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采用原位聚合法制备了含有N-甲基、丙基哌啶双三氟甲磺酰亚胺离子液体的凝胶型聚合物电解质.利用SEM和XPS测试了电解质膜与LiFePO4电极的界面状态,充放电循环后,在电解质膜与LiFePO4之间有一层薄膜,这层薄膜中含有N和S元素.结果表明,随着充放电的不断进行,凝胶型电解质中未聚合的甲基丙烯酸甲酯与电极表面的锂离子之间发生电子转移,形成SEI膜,至少要三个循环后才能形成稳定的SEI膜.随着SEI膜的增厚,放电容量增加,阻碍了电子转移,使系统更加的稳定.在不同倍率下测试了凝胶型离子液体/PMMA聚合物电解质电池性能,当充放电达到30个循环时,0.2、0.5和1C下电池比容量分别为132、128和120mAh/g. 相似文献