Striped patterns self-assembled from rod–coil diblock copolymers on spherical substrates

Abstract

In this work, the structures and topological defects of striped patterns self-assembled from rod–coil diblock copolymers confined on spherical substrates were examined using dissipative particle dynamics simulations. The stripes were formed by orderly packed rod blocks that were stabilized by coil blocks in solvents. Three types of disclinations with charges of +1, +1/2, and −1/2 and dislocations were observed in the striped patterns. The sum of the disclination charges was always +2, which is consistent with the Poincaré–Hopf theorem. Two categories of local defect stripe patterns were observed, namely, spiral-like and ring-like. The structures and surface densities of the defects were found to depend on various parameters, including the rigidities of the rod blocks, the radii of the spheres and the hydrophobicities of the rod blocks. The predictions were compared with our previous experimental observations and agreement was found. This work provides a method for producing striped patterns on curved substrates and can serve as a theoretical support for preparing nanoparticles with complex surface structures.