Mechanistic Study on the Shape Transition of Block Copolymer Particles Driven by Length-Controlled Nanorod Surfactants

Interface engineering of evaporative emulsion droplets containing block copolymers (BCPs) provides an effective route to generate nonspherical particles. Here, we demonstrate the impact of length-controlled nanorods (NRs) on the interfacial properties of BCP emulsions to produce anisotropic BCP particles. A series of lamellae- and cylinder-forming polystyrene- b -poly(4-vinylpyridine) (PS- b -P4VP) and a series of NRs with different lengths ( l ) are coassembled, and selective arrangement of the NRs on the P4VP domain at the particle surface enables the production of striped football (prolate) and convex lens-shaped (oblate) particles. In particular, the ratio of the NR length to the size of the NR-hosting domain ( l / L ), which is varied from 0.07 to 3.60, is the key parameter in determining the location of the NRs in the BCP particles as well as the final particle shape. The oblate pa…