Thermodynamic Description of the LCST of Charged Thermoresponsive Copolymers
Thermodynamic Description of the LCST of Charged Thermoresponsive Copolymers
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DOI：
10.1021/ma402577h
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发表时间：
2014-03-25
期刊：
影响因子：
5.5
通讯作者：
Dzubiella, Joachim
中科院分区：
文献类型：
--
作者：
Heyda, Jan;Soll, Sebastian;Dzubiella, Joachim
采用系统的云点实验和宏观热力学分析理论，研究了带电热敏性共聚物的下临界溶液温度（LCST）与电荷分数和盐浓度的关系。后者是基于Donnan平衡的概念，并将其纳入围绕电荷中性参考均聚物的两态自由能的热力学扩展中，并应适用于弱电荷（或高盐）聚合物体系。对于反应性共聚物聚（NIPAM-co-EVImBr）的水溶液，仅使用两个全局物理拟合参数，在很大的盐浓度和高达8%的电荷分数范围内，理论描述与实验结果非常吻合。我们的模型可以作为一个有用的指导，以优化热敏共聚物结构在未来的软，聚合物基材料的设计。
The dependence of the lower critical solution temperature (LCST) of charged, thermosensitive copolymers on their charge fraction and the salt concentration is investigated by employing systematic cloud-point experiments and analytical theory on a macroscopic thermodynamic level. The latter is based on the concept of the Donnan equilibrium incorporated into a thermodynamic expansion of a two-state free energy around a charge-neutral reference homopolymer and should be applicable for weakly charged (or highly salted) polymer systems. Very good agreement is found between the theoretical description and the experiments for aqueous solutions of the responsive copolymer poly(NIPAM-co-EVImBr) for a wide range of salt concentrations and charge fractions up to 8%, using only two global, physical fitting parameters. Our model could be useful as a guide for the optimization of thermoresponsive copolymer architectures in the future design of soft, polymer-based materials.