Department of Chemical and Biomolecular Engineering, The University of Maryland, College Park, College Park, Maryland 20742, USA.
Langmuir. 2009 Dec 1;25(23):13402-11. doi: 10.1021/la9019876.
We have studied the self-assembly of a polybutadiene-b-poly(ethylene oxide) diblock copolymer in methanol, in cyclohexane, and in the partially miscible binary mixture of methanol + cyclohexane. Molecular probe experiments indicated that PB(89)-b-PEO(132) (subscripts indicate the number of monomers in each block) forms micelles with PEO cores and PB coronas in pure cyclohexane and micelles with PB cores and PEO coronas in pure methanol. In both pure solvents, dynamic light scattering indicated that the copolymer forms coexisting spherical and cylindrical micelles. In the binary solvent mixture, only spherical micelles are observed. In the methanol-rich phase, spherical micelles form over a wide range of temperatures. In the cyclohexane-rich phase, spherical micelles are present only near the upper critical solution temperature of the mixture. At the critical solvent composition, spherical micelles form in the single-phase region above the critical temperature. Size-exclusion chromatography showed that for the binary solvent mixture the copolymer distributes mostly into the methanol-rich phase and that this preference becomes more pronounced as the temperature decreases.
我们研究了聚丁二烯-b-聚（氧化乙烯）嵌段共聚物在甲醇、环己烷以及甲醇+环己烷部分混溶性的二元混合物中的自组装。分子探针实验表明，在纯环己烷中，PEO 核和 PB 冠的 PB(89)-b-PEO(132)（下标表示每个嵌段的单体数）形成胶束，在纯甲醇中形成 PB 核和 PEO 冠的胶束。在这两种纯溶剂中，动态光散射表明共聚物形成了共存的球形和圆柱形胶束。在二元溶剂混合物中，只观察到球形胶束。在富含甲醇的相中，球形胶束在很宽的温度范围内形成。在富含环己烷的相中，仅在接近混合物的上临界溶液温度时存在球形胶束。在临界溶剂组成下，在高于临界温度的单相区形成球形胶束。尺寸排阻色谱表明，对于二元溶剂混合物，共聚物主要分布在富含甲醇的相中，随着温度的降低，这种偏好变得更加明显。
