两亲性/双疏性嵌段共聚物共混体系的自组装行为研究

Self-assembly Behavior of Mixtures of Amphiphilic AB Block Copolymers and Solvophobic BC Block Copolymers

采用耗散粒子动力学方法,研究了两亲性嵌段共聚物和双疏性嵌段共聚物共混体系的自组装行为,探讨了双疏性嵌段共聚物的浓度以及双疏性嵌段共聚物的嵌段体积分数对聚集体结构的影响.结果表明,随着双疏性嵌段共聚物浓度的增加,聚集体发生自囊泡到棒状胶束再到同心圆多舱胶束的转变,且当浓度较高时,同心圆多舱胶束的同心圆层数量与浓度密切相关.当双疏性嵌段共聚物中的嵌段体积分数降低时,球形胶束由同心圆结构转变为非同心圆结构.此外,利用Minkowski泛函方法表征了多舱胶束的形成过程,发现这是一个先形成大尺度球形结构、再形成小尺度内核结构的分级组装过程.

Self-assembly of mixtures of amphiphilic AB diblock copolymers and solvophobic BC diblock copolymers in selective solvents was investigated by dissipative particle dynamics simulations. A series of aggregates such as multicompartment micelles were observed. Density profiles of the aggregates were plotted to gain insight into the details of the aggregates. It was found that the BC block copolymers mainly occupy the cores of the aggregates to increase the hierarchy of the structures. Effects of eopolymer concentration and block length on the aggregates were studied. As the concentration of BC diblock copolymers increases, a morphological transformation from vesicles to cylindrical micelles and then to spherical multicompartment micelles occurs. At high concentration of BC diblock copolymers, the number of concentric layers within spherical micelles was found to be significantly dependent on the concentration of BC copolymers. By tuning the block length of C block length, both the concentric and nonconcentric multicompartment micelles were found. In addition to the morphological studies, the dynamic process was further analyzed with Minkowski functionals. The results show that the formation of muhieompartment micelles is a hierarchical process of selfassembly. During the self-assembly, the large-length-scale structures are first formed, and then the small-lengthscale structures within the cores gradually appears. The present simulation resuhs could provide in-depth information about the mechanism behind the formation of muhicompartment micelles from mixtures of amphiphilic and solvophobic copolymers, and also could provide guide for preparation of controllable structures for advanced functional nano-devices.