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

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 copolymer 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 multicompartment micelles is a hierarchical process of self-assembly. During the self-assembly, the large-length-scale structures are first formed, and then the small-length-scale structures within the cores gradually appears. The present simulation results could provide in-depth information about the mechanism behind the formation of multicompartment micelles from mixtures of amphiphilic and solvophobic copolymers, and also could provide guide for preparation of controllable structures for advanced functional nano-devices.