The Polymer Society of Korea

Abstract

Bottlebrush block copolymers (BBCPs) consist of densely grafted side chains arranged in chemically distinct blocks, leading to assembly behavior distinct from that of linear block copolymers. Steric crowding from side chains enforces stretched backbone conformations, which increases the energetic cost of curved interfaces and generally disfavors curved morphologies under equilibrium conditions. Herein, we show that spherical nanostructures can be realized in BBCP systems by employing polymerization-induced microphase separation (PIMS) to capture interfacial curvature at an early stage of assembly. By fixing curvature during polymer growth by kinetically arresting the structure, this approach circumvents the thermodynamic bias toward flat interfaces and enables access to highly curved morphologies that are otherwise difficult to obtain in equilibrium BBCP self-assembly. Such spherical BBCP nanostructures enable the exploration of curvature-dominated packing under strong steric constraints and offer robust, isotropic nanostructures.