离子液体二元溶液的临界现象

The critical behaviors of a series of binary mixtures of ionic liquid + alchol will be studied. The liquid-liquid coexistence curves are determined by measuring the refractive index in two coexisting phases; the Micro-DSC is used to measure the heat capacities in both one-phase and two-phase regions; the turbidity measurement is carried out near the critical region both above and below the critical temperature.The obtained experimental data are analyzed to get the critical exponents and scaling relations of the critical amplitudes, which are used to discuss their critical universality. The analysis of the asymmetric behaviors of the coexistence curve diameter and the osmotic compressibility is conducted to extend the application of the complete scaling theory to ionic solutions.

以一系列离子液体和不同链长的醇为研究体系，采用折射率法测量它们在液液临界点附近的共存曲线，采用DSC测量它们在一相区及两相区的热容，采用浊度仪测量它们在近临界一相区和两相区共存两相的浊度；通过数据分析得到临界指数和指前因子的标度关系，讨论它们的临界普适性和普适性类别。通过对共存曲线直径和渗透压缩系数不对称性的分析，拓展完全标度理论在离子溶液中的应用。

以一系列含离子液体二元溶液为研究体系，测量了（1）临界点附近的共存曲线；（2）近临界一相区、两相区及远临界一相区的热容；（3）近临界点附近一相区和两相区的浊度。由上述实验数据分析得到：（1）共存曲线宽度，热容，关联长度和渗透压缩系数对应的临界指数及指前因子；（2）描述临界不对称行为的不对称因子a1. 研究表明：（1）含离子液体二元溶液的临界指数及临界指前因子的比例关系与3D-Ising模型理论预测一致，表明含离子液体的二元溶液的临界行为与其他简单分子溶液一样属于3D-Ising普适类别；（2）随着溶剂介电常数的增加，离子溶液相变驱动力显示出从库仑力向疏溶剂作用的转变；（3）完全标度理论可以很好地描述含离子液体二元溶液共存曲线直径及渗透压缩系数的临界不对称行为，且分析两者不对称行为得到的不对称因子a1的结果一致；（4）离子溶液中可能存在的超分子聚集结构显著影响其临界跨接行为。