Syntheses and applications of concave and convex colloids with precisely controlled shapes

This article describes a facile and promising method to prepare uniform, non-spherical colloidal particles with shape and chemical anisotropies. We first synthesize polystyrene (PS) colloids with a concave multi-dimple structure, through a unique combination of two-stage dispersion polymerizations and a programmed feeding of cross-linker during the synthesis. These concave particles, after a seeded polymerization process, can be swelled out to precisely controlled shapes by varying the amounts of the swelling chemicals. A myriad of concave- and convex-shaped colloidal particles, including hemispheres, peanuts and bowls are obtained. In addition, we explore the potential applications of the synthesized anisotropic colloids by looking at the field-driven directional self-assembly, the optical hiding effect and their use as colloidal surfactants.