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 the liquid template in emulsion droplets. By increasing the volume ratio of PFO to polystyreneb/ock-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 the block ratio or molecular weight or by adding a hydrogen-bonding agent. Based on the in situ optical microscopy investigation of the morphology evolution of the 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.