Morphological transition behavior of ABC star copolymers by varying the interaction parameters.

We employ dissipative particle dynamics (DPD) to examine the effects of composition and interaction parameter on the resulting phase behavior of ABC star copolymers. Here, we assume that the interaction parameters among the three components are equal. When the three components have comparable volume fractions, our DPD results illustrate that the unique formation of various types of three-phase separated polygonal cylinders is mainly dominated by the composition but not influenced by the interaction parameter. In contrast, when two of the three components are minor, the resulting morphology type is greatly influenced by the interaction parameter. Generally speaking, with an increase in the interaction parameter, the two minority components first act like one component and the system forms a one-length-scale ordered microstructure. Then a further segregation between the two minority components within the large-length-scale phase can be induced as the interaction parameter keeps increasing. In general, our DPD results, a systematic study of the morphological transition behavior obtained by varying the interaction parameter and composition, bridge the gap between the previous theoretical results in the strong and weak segregation regimes via Monte Carlo and two-dimensional self-consistent mean-field methods, respectively.