Tsekov Roumen
Department of Physical Chemistry, University of Karlsruhe, 76131 Karlsruhe, Germany.
J Chem Phys. 2007 May 21;126(19):191110. doi: 10.1063/1.2741507.
A simple theoretical model is developed describing ionic liquids as regular solutions. The separation of these ionic mixtures is studied on the base of the Cahn-Hilliard theory coupled with electrostatics. It is shown that the ionic liquids decompose to thin layers of oppositely charged liquids at low temperatures. At larger temperatures the separation occurs only near the ionic liquid/vacuum surface, thus explaining the oscillatory-decaying structure of the electric double layer observed via computer simulations. In contrast to noncharged liquids the ionic ones exhibit two critical temperatures, where the temperature coefficients of all characteristic lengths possess singularities. These second order ferroelectric phase transitions are possible explanations of the experimentally measured via light scattering peculiar temperature dependence of the interfacial dipole moment density on several ionic liquid/vacuum interfaces.
开发了一个简单的理论模型，将离子液体描述为规则溶液。基于结合静电学的Cahn-Hilliard理论研究了这些离子混合物的分离。结果表明，离子液体在低温下会分解为带相反电荷的液体薄层。在较高温度下，分离仅发生在离子液体/真空表面附近，从而解释了通过计算机模拟观察到的双电层的振荡衰减结构。与不带电的液体不同，离子液体表现出两个临界温度，在这些温度下所有特征长度的温度系数都具有奇异性。这些二级铁电相变可能是通过光散射实验测量的几个离子液体/真空界面上界面偶极矩密度对温度的特殊依赖性的原因。
