星形胶束自由能和聚集数的理论分析

ＡＢ型嵌段聚合物在选择性溶剂中将发生微相分离,形成一种球形胶束1].所谓选择性溶剂是指此溶剂仅能溶解共聚物中某一链段,而对另一链段则为不良溶剂.对这一体系的实验研究是从80年代兴起的,主要采用现代测试技术来表征形成胶束的回转半径2],动力学半径3]、聚集数4]和临界胶束浓度5].从分子图景上看来,这种球形胶束包括两部分,内核(Ｃｏｒｅ)为密堆砌的链段Ａ;壳层(Ｃｏｒｏｎａ)为溶涨的链段.Ｈｅｌｆａｎｄ等6]最早利用数值计算法来研究嵌段聚合物在本体中的微相分离的问题;Ｌｅｉｂｌｅｒ等7]将此方法引入嵌段聚合物/均聚物体系.…

THEORETICAL PREDICTIONS OF FREE ENERGY AND AGGREGATION NUMBER FOR STAR-SHAPED MICELLES

Considering the inhomogeneity of the concentration distribution in the corona of a star\|shaped micelle, an equation system of free energy components was suggested in order to predict the micro\|phase separation of the diblock copolymer in selective solvents. All energetic and entropic contributions to the free energy of micellization were included in equations for the micellar solution, which was composed of the di\|block copolymers with certain molecular weights and the solvent with special characters at a giving temperature. The minimization of free energy produced the equilibrium size and aggregation number of the micelle. The corona and core size of the micelle,the concentration profile of the soluble block in corona and the value of the aggregation number were obtained based on the present theory. Moreover, the theoretical predictions of the aggregation number were in good agreement with the experimental data for systems of polystyrene\|poly(2\|cinnamoylethyl methacrylate)/cyclopentane and poly(4\|vinylpyridine) \|polystyrene/toluene.