Shape-Anisotropic Diblock Copolymer Particles with Varied Internal Structures.

Anisotropic polymer particles have promising applications in various fields, whereas their preparation usually suffers from tedious procedures. Here, we introduce a facile strategy to fabricate novel shape-anisotropic particles with varied internal structures via self-assembly of block copolymers (BCPs) with perfluorooctane (PFO) as liquid template in emulsion droplets. By increasing the volume ratio of PFO to polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) or decreasing the initial concentration of the BCPs, the self-assembled polymer particles change from spherical core-shell structures to anisotropic particles. Moreover, the anisotropic shape and internal structure of the polymer particles, including cone-like particles with alternative PS and P4VP lamellas, crescent-shaped particles with cylindrical P4VP domains, and plate-like particles with spherical P4VP domains, can be obtained by changing block ratio, molecular weight, or adding hydrogen bonding agent. Based on the in-situ optical microscopy investigation on the morphology evolution of emulsion droplet, we conclude that both kinetic and thermodynamic factors during emulsion evolution determine the formation of shape-anisotropic polymeric particles with controllable internal structures.