Morphology and molecular bridging in comb- and star-shaped diblock copolymers

Block copolymers spontaneously self-assemble into nanostructured morphologies with industrially attractive properties; however, the relationships between polymer architecture and self-assembled morphology are difficult to tailor for copolymers with increased conformational restrictions. Using Dissipative Particle Dynamics, the self-assembled morphology of comb- and star-shaped diblock copolymers was simulated as a function of the number of arms, arm length, weight fraction, and A-B incompatibility. As the number of arms on the star, or grafting points for the comb, was increased from three to four to six, the ability to self-assemble into ordered morphologies was restricted. The molecular bridging between adjacent ordered domains was observed for both comb- and star-shaped copolymers, which was found to be enhanced with increasing number of arms. This study illustrates that comb- and star-shaped copolymers are viable alternatives for applications that would benefit from highly bridged nanostructural domains.