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Microheterogenities and Crossover from Ising to Mean Field Criticality in Solutions of Ionic Liquids

离子液体溶液中的微观异质性和从 Ising 到平均场临界值的交叉

基本信息

批准号：
29324948
负责人：
Professor Dr. Wolfram Schröer
金额：
--
依托单位：
依托单位国家：
德国
项目类别：
Priority Programmes
财政年份：
2006
资助国家：
德国
起止时间：
2005-12-31 至 2009-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/29324948?language=en
关键词：
Microheterogenities Crossover Ising Mean Field

项目摘要

Structure and dynamics of solutions of Ionic Liquids will be investigated on a mesoscopic scale by static and dynamic light scattering. Near a critical solution point the critical fluctuations dominate the scattering, but other equilibrium and non-equilibrium inhomogeneities contribute and will be analyzed applying new techniques. Corresponding state analysis indicates that in non-polar solvents the liquid-liquid phase transition is determined by the Coulomb interactions, while with increasing polarity solvophobic interactions become dominant. It was shown that the liquid-liquid phase transitions of ionic solutions always belong to the Ising universality class. While the nature of the critical point is unchanged, when Coulomb forces or solvophobic interactions drive the phase transition, it is not clear if this is true also for the crossover from Ising to regular behaviour. Some theories predict a large, others a small non-classical region with crossover to a tricritical point, when Coulomb forces drive the phase transition. However, non-critical mesoscopic structures may erroneously be interpreted as crossover. To clarify the situation, we will investigate the light-scattering of solutions of Ionic liquids in solvents of different dielectric constant including hydrocarbons, alcohols and water. Solutions of Ionic Liquids that are able to form liquid crystals will be investigated as in such systems crossover to a tricritical point is quite likely.

将通过静态和动态光散射在介观尺度上研究离子液体溶液的结构和动力学。在临界解点附近，临界波动主导散射，但其他平衡和非平衡不均匀性也有贡献，并将应用新技术进行分析。相应的状态分析表明，在非极性溶剂中，液-液相变是由库仑相互作用决定的，而随着极性的增加，疏溶剂相互作用变得占主导地位。结果表明，离子溶液的液-液相变始终属于伊辛普适类。虽然临界点的性质没有改变，但当库仑力或疏溶剂相互作用驱动相变时，尚不清楚从伊辛到常规行为的交叉是否也是如此。一些理论预测，当库仑力驱动相变时，会出现一个大的非经典区域，另一些理论预测一个小的非经典区域会交叉到三临界点。然而，非关键介观结构可能会被错误地解释为交叉。为了澄清这一情况，我们将研究离子液体溶液在不同介电常数的溶剂（包括碳氢化合物、醇和水）中的光散射。将研究能够形成液晶的离子液体溶液，因为在此类系统中很可能跨越三临界点。