离子液体参与原子转移自由基聚合的研究进展

主要阐述了近年来离子液体作为溶剂、单体或者配位剂在原子转移自由基聚合中的应用研究情况.从对聚合反应速率的大小的影响,聚合产物分子量多分散系数的变化,聚合物分子链功能性的设计,以及反应体系中催化体系的分离与循环使用等方面总结了离子液体的参与对原子转移自由基聚合的影响,并简要总结了导致各种变化的原因.最后展望了离子液体应用于原子转移自由基聚合技术的前景,并指出离子液体自身研究的发展是二者结合的关键问题.     

自由基聚合反应的新介质——离子液体的新应用

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。     

离子液体在自由基聚合反应中的应用研究进展

室温离子液体是完全由离子构成的液体,具有几乎没有蒸汽压、溶解度大、溶解范围广、易于回收利用、稳定性好等特点,广泛应用于电化学、有机反应、分离萃取、复合材料等各个领域。近年来已成为各种聚合反应研究的重要课题,且主要集中于自由基聚合反应。作为聚合反应的溶剂,离子液体对聚合反应速率、分子量、聚合物的结构性能都有一定影响。本文根据近几年的文献,归纳分析了离子液体中的常规自由基聚合和活性自由基聚合的反应动力学、反应机理、聚合产物的结构和性能以及离子液体的回收利用等问题。     

由平面合成聚合物刷--表面引发原子转移自由基聚合研究进展

原子转移自由基聚合反应(ATRP)是实现活性聚合,获得可控聚合物的一种有效途径。通过表面引发原子转移自由基聚合,在材料表面合成聚合物刷,是改变材料表面特征的有效方法。本文综述了表面引发原子转移自由基聚合合成聚合物刷及其最新进展。     

原子转移自由基聚合与高分子构筑

活性聚合反应是目前高分子合成研究最为活跃的领域之一，原子转移自由基聚合反应（ATRP）是实现活性聚合的一种有效途径，可实现多种单体的活性聚合和可控自由基聚合。本文介绍了原子转移自由基聚合反应机理，重点综述了原子转移自由基聚合在高分子合成中的应用。     

室温离子液体中的聚合反应

综述了近年来在室温离子液体中聚合反应的研究进展,特别是在配位聚合、自由基聚合、离子聚合及共聚反应,活性自由基聚合,电化学聚合等方面的进展情况;还介绍了离子液体在高分子材料方面的应用情况,展望了离子液体在该领域的应用前景.     

丙烯酰胺在离子液体中的原子转移自由基聚合

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%,M_n^GPC=4451,M_w/M_n=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。     

原子转移自由基聚合(ATRP)在星形聚合物合成中的应用

综述了近10 年来采用原子转移自由基聚合(ATRP) 法合成星形聚合物的研究进展。从聚合单体、引发剂、聚合方法和反应条件以及聚合物性质等方面讨论了原子转移自由基聚合在星形聚合物合成中的应用,并根据聚合方法和引发剂对各种反应进行了分类。对原子转移自由基聚合技术在合成功能性复杂星形聚合物中的应用进行了展望。     

AIBN/SmCl3/乳酸体系催化甲基丙烯酸甲酯的反向原子转移自由基聚合

利用稀土金属化合物三氯化钐(SmCl3)和二氯化钐(SmCl2)之间的单电子转移反应,以AIBN/SmCl3/乳酸作为反向原子转移自由基聚合(ReverseATRP)的催化体系,成功地实现了甲基丙烯酸甲酯(MMA)的反向ATRP,并考察了温度、溶剂和组分比对聚合反应的影响.MMA在该体系中的聚合反应是一级反应,所得PMMA的分子量与单体转化率成正比,聚合物的分子量分布较窄(Mw/Mn<1.5),具有活性聚合的特征.     

点击化学与活性自由基聚合联用构建特殊结构聚合物

点击化学由于其高效、可靠、高选择性等特点,一经提出便在复杂结构聚合物制备上得到广泛关注,而活性自由基聚合则具有聚合过程和聚合物结构可控等特点.本文综述了点击化学与活性自由基聚合方法如原子转移自由基聚合(ATRP),可逆加成断裂链转移聚合(RAFT),氮氧调控活性自由基聚合(NMP),以及原子转移氮氧自由基聚合反应(AT...     

Polymerization Processes in Ionic Liquids. Cationic Polymerization of Styrene

There is an increasing interest in using ionic liquids as solvents for polymerization processes. Most published data deals with controlled radical polymerization. It has been shown that ionic liquids offer several advantages for conducting Atom Transfer Radical Polymerization (ATRP), such as good solubility of catalyst and improved k_p/k_t ratio. Ionic liquids are highly polar therefore they seem to be suitable solvents for conducting also ionic polymerization processes. In our preliminary communication we reported on cationic polymerization of styrene initiated by R-Cl/TiCl₄ system in ionic liquid. To clarify the mechanism of this process, racemization of optically active 1-phenylethyl choride (initiator and the model of dormant species) was studied and it was shown that in ionic liquid racemization proceeds even in the absence of coinitiator (TiCl₄). Because racemization proceeds through ionization of C Cl bond, this explains the cationic polymerization of styrene initiated by R-Cl alone (in the absence of coinitiator). Chain transfer, however, cannot be eliminated, therefore polymerization is not controlled.     

Free Radical Polymerization of Acrylonitrile in Green Ionic Liquids

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.     

Ionic liquids in the synthesis and modification of polymers

Ionic liquids are organic salts that are liquid at ambient temperatures, preferably at room temperature. They are nonvolatile, thermally and chemically stable, highly polar liquids that dissolve many organic, inorganic, and metallo‐organic compounds. Many combinations of organic cations with different counterions are already known, and the properties of ionic liquids may be adjusted by the proper selection of the cation and counterion. In the last decade, there has been increasing interest in using ionic liquids as solvents for chemical reactions. The interest is stimulated not only by their nonvolatility (green solvents) but also by their special properties, which often affect the course of a reaction. In recent years, ionic liquids have also attracted the attention of polymer chemists. Although the research on using ionic liquids in polymer systems is still in its infancy, several interesting possibilities have already emerged. Ionic liquids are used as solvents for polymerization processes, and in several systems they indeed show some advantages. In radical polymerization, the k_p/k_t ratio (where k_p is the rate constant of propagation and k_t is the rate constant of termination) is higher than in organic media, and thus better control of the process can be achieved. Ionic liquids, as electrolytes, have also attracted the attention of researchers in the fields of electrochemical polymerization and the synthesis of conducting polymers. Finally, the blending of ionic liquids with polymers may lead to the development of new materials (ionic liquids may act as plasticizers, electrolytes dispersed in polymer matrices, or even porogens). In this article, the new developments in these fields are briefly discussed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4675–4683, 2005     

Selection of Ionic Liquids for Free Radical Polymerization Processes

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.     

室温离子液体在聚合反应中的应用

室温离子液体作为一种环境友好的“绿色溶剂”,具有很多独特的物理化学性能,可以应用于自由基聚合、阳离子聚合、配位聚合、电化学聚合等反应体系。本文介绍了室温离子液体在上述反应中的应用。     

Ionic Liquids - New Solvents in the Free Radical Polymerization

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 k_p and termination k_t. 2 - 4 The rate constant of termination k_t decreases when the IL concentration and therefore the viscosity of the reaction mixture is increased, whereas the propagation rate coefficient k_p 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.     

烯类单体在室温离子液体中的自由基聚合反应研究进展

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。     

高分子离子液体的研究进展

综述了高分子离子液体最新的研究进展。作为离子液体的载体材料主要有两大类 :一是无机高分子 ,离子液体中的阴离子或阳离子通过与无机高分子材料表面的基团键合形成含离子液体结构的高分子 ;二是有机高分子 ,在有机高分子上引入离子液体合成聚合物电解质 ,并介绍了其在催化、导电材料方面的应用前景