Disk-Like Micelles with a Highly Ordered Pattern from Molecular Bottlebrushes.

Abstract

Self-assembling amorphous macromolecules into nanoparticles with a highly ordered internal structure and a defined shape is always a big challenge. Herein we present formation of soft disk-like micelles by hexagonally packing AbBA amphiphilic triblock copolymers, whose bB block is the molecular bottlebrush with densely grafted poly(t-butyl acrylate)-b-polystyrene (PBA-b-PS) branches and A block is poly(N-(2-methacryloyloxyethyl)pyrrolidone) (PNMEP). In a selective solvent of A segment, it was found that the AbBA molecular bottlebrushes with stiffened middle blocks self-assembled two-dimensionally into disks with a uniform thickness of about 33 nm and a diameter of hundreds of nanometers. A hexagonal pattern of molecular bottlebrushes aligned perpendicularly to the disk plane with a periodic spacing of 9 nm was visualized by TEM through selective staining the PS shells of brushes. The aggregation number of AbBA molecular bottlebrushes in each disk was counted directly from the stained TEM image.