混合表面活性剂溶液的热力学性质

The thermodynamic properties of a series of mixed surfactant solutions of alkanediyl-α,ω-bis (dimethylalkylammonium bromide) / 1-dodecyl-3-methyllimidazoliumbromide will be studied. The micellization enthalpy and the conductivity will be determined by the isothermal titration calorimetry and the conductometry, which are analyzed to get the enthalpy of micellization and the degree of dissociation of counterion and further to get the Gibbs free energy and the entropy of micellization. The more precise composition, activity coefficient and excess Gibbs free energy of mixed micelles will be deduced from the Margules equation. On the basis of a pseudo phase model, a method for calculating excess enthalpy of the mixed micelles through micellization enthalpy will be established, and further the excess entropy be obtained, which together with the excess volume determined by the density measurement facilitate to understand the interactions in the mixed micelle system. The microenvironmental polarity, the fluorescence anisotropy, the aggregation number and the size of mixed micelles will be investigated by the fluorimetry and the light scattering, respectively. Combining these experiment methods, the relationship between the microstructures and the macroscopical thermodynamic properties of mixed micelles will be probed.

以一系列α,ω-烷基-二(十二烷基二甲基溴化铵)/1-十二烷基-3-甲基咪唑溴化盐水溶液为研究体系，用等温滴定量热仪测量该一系列体系的胶束化焓变，用电导率仪测量电导，通过数据分析得到胶束化焓、胶束化自由能和胶束化熵，反离子解离度；引进Margules 方程进行数据分析，得到更精确的混合胶束的组成、活度系数，超额自由能；在假相模型的基础上构建一个通过测量混合胶束的胶束化焓得到超额焓的方法，进而计算超额熵，研究混合胶束之间的相互作用；通过测量密度，获得混合胶束超额体积；用荧光光度计测量混合胶束的微极性、各向异性和聚集数，用光散射仪测量胶束的尺寸，探索混合胶束微观结构与宏观热力学性质的联系。

本项目主要测量双子型表面活性剂与单链表面活性剂混合溶液的电导、稀释热、密度、微极性、各向异性、聚集数和半径，利用Margules方程进行数据分析，得到胶束化吉布斯自由能变和熵变。建立通过测量混合胶束的胶束化焓变得到超额焓的方法，得超额焓、超额熵等数据。建立通过胶束混合焓变得到胶束间相互作用焓变的方法，探索了胶束相互作用本质。