Confinement of semi-crystalline bottlebrush random copolymers

Bottlebrush copolymers incorporating distinct segments feature unique architectures and variable composition, affording unique opportunities to manipulate self-assembly and phase transitions. We synthesized a series of bottlebrush random copolymers (BRCP) with polystyrene (PS) and poly (ethylene oxide) (PEO) side chains. The bottlebrush architecture, where the side chains are anchored to backbone, inherently restrict the mobility of PEO. The relatively higher glass transition temperature of PS, compared to the crystallization temperature of PEO, places further confinement of PEO crystallization to the microdomain morphology established by the PS. The resultant limited mobility of PEO hinders its crystallization, ultimately leading to unusual microphase separation behavior and self-assembled structures. Confinements were adjusted by changing BRCP architectures as well as the annealing conditions to reveal the underlying mechanism.