BLOCK COPOLYMER SELF-ASSEMBLY IN SELECTIVE SOLVENTS - THEORY OF SOLUBILIZATION IN SPHERICAL MICELLES
BLOCK COPOLYMER SELF-ASSEMBLY IN SELECTIVE SOLVENTS - THEORY OF SOLUBILIZATION IN SPHERICAL MICELLES
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DOI：
10.1021/ma00201a029
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发表时间：
1989-11-01
期刊：
影响因子：
5.5
通讯作者：
GANESH, K
中科院分区：
文献类型：
--
作者：
NAGARAJAN, R;GANESH, K
本文提出了在选择性溶剂S中AB两嵌段共聚物胶束增溶低分子量化合物J的理论。该处理假定胶束为球形结构。在这些球形胶束中，可以看到溶剂S和聚合物的溶剂相容性B嵌段完全被排除在核心区域之外，而几乎所有的增溶物分子J都位于其中。考虑到变形状态和聚合物嵌段的稀释状态、胶束界面的形成和共聚物的局部化，所有这些都伴随着增溶过程，已经模拟了增溶的自由能。在此自由能模型的基础上，该理论可以预测临界胶束浓度、胶束的大小和组成分布、胶束的聚集数、最大增溶范围、胶束的核半径和壳厚度。说明性的计算表明，在一般情况下，胶束几乎是单分散的大小和增溶的程度。胶束的增溶行为和它们的几何特征被发现是显着的增溶物J和溶剂不相容的共聚物的A嵌段之间的相互作用，以及增溶物J-溶剂S的界面张力的影响。胶束的结构参数也受到溶剂S和聚合物的溶剂相容性B嵌段之间的相互作用的影响，但与相应的无增溶物体系相比，影响程度稍低。广义标度关系已经开发，明确涉及胶束核心半径，壳厚度，和themicelle核心内的增溶物的体积分数的共聚物，溶剂和增溶物的分子特征。本理论的预测已与我们早期的实验数据进行了比较，在水溶液中的二嵌段共聚物的烃的增溶。
A theory of solubilization of low molecular weightcompounds J in micelles of AB diblock copolymer formed in a selective solvent S is developed in this paper. The treatment assumes a spherical structure for themicelles. In these spherical micelles, it is visualized that the solvent S and the solvent-compatible B blockof thecopolymer are entirely excluded from the core region, whereas almost all of the solubilizate molecules J are located within. The free energy of solubilization has been modeled taking into account the variations in thestates of deformation and in the states of dilution of the polymer blocks, the formationof the micellar interface, and the localization of the copolymer, all accompanying the solubilization process. On the basis of this free energy model, the theory permits the prediction of the critical micelle concentration, the size and composition distribution of the micelles containing solubilizates, the aggregation number of the micelles, the maximum extentof solubilization, and the core radius and the shell thickness of the micelles. Illustrative calculations show that, in general, the micelles are practically monodispersed both intheir size and in the extent of solubilization. The solubilization behavior of the micelles and their geometrical characteristics are found to be significantly influenced by the interactions between the solubilizate J and the solvent-incompatible A block of the copolymer as well as by the solubilizate J-solvent S interfacial tension. The micellar structural parameters are affected also by the interactions between the solvent S and the solvent-compatible B block of thecopolymer though to a somewhat lower degree when compared to the corresponding solubilizate-free systems. Generalized scaling relations have been developed that explicitly relate the micelle core radius, the shell thickness, and the volume fractionof the solubilizate within themicelle core to the molecular features of the copolymer, the solvent, and the solubilizate. The predictions of the present theory have been compared against our earlier experimental data on the solubilization of hydrocarbons in aqueous solutions of diblock copolymers.