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

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 ABA amphiphilic triblock copolymers, whose B block is the molecular bottlebrush with densely grafted poly(-butyl acrylate)--polystyrene (PBA--PS) branches and A block is poly(-(2-methacryloyloxyethyl)pyrrolidone) (PNMEP). In a selective solvent of A segment, it was found that the ABA 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 ABA molecular bottlebrushes in each disk was counted directly from the stained TEM image.