【作者】 韩超；

【导师】 陈晓春；

【作者基本信息】 北京化工大学 ， 化学工艺， 2010， 硕士

【摘要】 离子液体是近十几年内才发展起来的一种全新的绿色溶剂,因其优异的物理化学性质,已经在诸多领域引起了广泛的研究兴趣。但离子液体有一个不足的地方,就是其粘度高(通常比传统有机分子型溶剂高1-3个数量级),高粘度已经成为制约离子液体工业化应用的瓶颈之一,如何降低其粘度成为离子液体研究领域的一个关键问题。然而目前人们对离子液体粘度的认识还很有限,因此,建立起离子液体微观结构与宏观粘度之间的定量关系,揭示离子液体粘度高的微观本质,对于低粘度离子液体的定向合成与设计有重要的意义。基于此,本文主要开展了如下研究：1)建立了咪唑类离子液体粘度的数据库,收集了1983-2009年间的粘度数据,共包括1731条数据条目,涉及255种离子液体(79种阳离子,71种阴离子)；2)基于所建数据库,定性分析了影响离子液体粘度的一些因素,发现了温度、压力、阳离子上的烷基侧链、阳离子C(2)位置甲基化、阴离子结构等对粘度的影响规律；3)从数据库中选出四类咪唑离子液体进行了定量结构性质关系(QSPR)研究,得到了较好的拟合模型(相关性系数R2>0.92),结果表明,阴阳离子间的静电作用对咪唑类离子液体粘度的影响很大,其它诸如氢键、范德华作用及分子体积、对称性、极化率等对粘度也有一定影响；4)将咪唑类离子液体粘度的QSPR结果与传统分子型有机溶剂粘度的QSPR结果进行了比较,发现,不同于分子型有机溶剂,在咪唑类离子液体中,阴阳离子间的静电作用是影响粘度的主要因素之一,而氢键作用、范德华作用次之。更多还原

【Abstract】 Owing to some desirable properties, ionic liquids (ILs) have attracted increasing interests and applications in many domains. Unfortunately, however, they generally have much higher viscosities than conventional molecular solvents, which results to some problems of handling or transferring in chemical processing. ILs with lower viscosity are desired. Therefore, understanding the relationship between micro-structure and macro-viscosity along with a comprehensive viscosity data is important for the synthesis and rational design of ILs with low viscosity.In this work:1) A comprehensive database on viscosities of ionic liquids, which has been collected from 142 kinds of literature sources in the period from 1984 through 2009, was established. The cations and anions were named and ordered according to their molecular weight. There are totally 79 kinds of cations,71 kinds of anions and 1731 pieces of data.2) Based on our data base, we got the qualitative analysis of ionic liquid structure on the viscosity and found that the temperature, pressure, cation alkyl side chain on the cation C(2) position to replace the anion structure affect the viscosity;3) quantitative structure-property relationship (QSPR) study is performed for four selected data sets. The four correlations are obtained with R2>0.93, and quantum-chemical descriptors gave significant contributions. The cation-anion electrostatic interaction has the significant effects on the viscosity of imidazolium-based ILs, while other interactions (e.g., interionic hydrogen-bond, Van der Waals) or micro-characteristics (e.g., molecular orbital, electronic population, polarizability, volume, shape, branching degree, symmetry) also give some effects.4) Compared with the viscosity of organic matter, it can be found that the electrostatic interaction between ions is no longer the main factor affecting for the viscosity, hydrogen bonding and van der of force are even more prominent role. Ionic liquids is not only in common with ordinary organic compounds, but also have their unique.更多还原