高聚物在二元混合溶剂中及其液-液临界点附近的热力学行为

The thermodynamic behaviors of a series of ternary polymer dilute solutions constituted by polymer + mixed solvents will be studied by measurements of the density through a vibrating densimeter, the isobaric heat capacity per unit volume through the Micro-DSC, and the dilution enthalpy through the isothermal titration calorimetry. The obtained experimental data will be analyzed to get the apparent molar volumes, the partial molar volumes, the apparent isobaric heat capacities per unit volume, the partial isobaric heat capacities per unit volume, and the excess enthalpies of the polymers in the mixed solvents, which are use to discuss the cosolvency or nonsolvency of the polymers in the binary mixed solvents. The analysis of above thermodynamic quantities near the liquid-liquid critical points will also be conducted to explore the anomalous thermodynamic behaviors and their relations to the conformations of the polymers.

以一系列高聚物/混合溶剂构成的三元高聚物稀溶液为研究体系，用振动管密度计测量密度，用DSC测量热容，用等温滴定量热技术测量稀释焓；通过数据分析得到不同温度和组成下高聚物的表观摩尔体积、偏摩尔体积、表观单位体积恒压热容、偏单位体积恒压热容和超额焓，探讨二元混合溶剂对高聚物的共溶或共非溶性质的影响。通过对逼近液-液临界点时上述热力学数据的分析，探索临界奇异性驱动的高聚物宏观热力学性质异变及其与高聚物构象转变的关系。

以{2-正丁氧基乙醇+水}二元混合溶剂与高聚物聚丙烯酸（PAA）或聚乙二醇（PEG）组成的三元溶液为研究体系，测量密度，热容和稀释焓，数据分析得到了高聚物的表观单元摩尔体积，表观无限稀释单元摩尔体积，表观单元摩尔热容，表观单元摩尔稀释焓。发现高聚物的表观单元摩尔性质与混合溶剂的组成有关。混合溶剂对聚丙烯酸是共非溶，大部分组成的混合溶剂对聚乙二醇是共溶的，但在富水混合溶剂表现为不良溶剂。通过建立缔合平衡模型分析热力学行为。由光散射和共振光散射实验测量进一步理解高聚物在二元混合溶剂中的构象变化。