Block copolymer-assisted synthesis of monodisperse colloidal patchy nanoparticles.

Amphiphilic block copolymers are able to assemble into spherical micelles in an aqueous solution. Spherical micelles are expected to adsorb on the surface of colloidal nanoparticles (NPs) through hydrogen-bonding interaction. Hence, it should be possible to guide the area-selective deposition of precursors onto the exposed surface of colloidal seeds, where no micelles are adsorbed. Using colloidal silica and polydopamine nanospheres as seeds, block copolymer F127 and P123 are used as surface modifiers to guide the controlled solution-phase deposition of precursors on a selectively exposed surface of seed NPs, leading to the formation of patchy NPs. Effects of the addition amount of tetraethoxysilane (TEOS), types of block copolymers, and the volume fraction of miscible organic solvents on the size and morphology of patchy silica NPs are investigated systematically through electron microscopic imaging. Block copolymer micelles adsorption model for the formation of colloidal patchy NPs is first proposed. Our study suggests that the shape and size of patchy silica NPs are determined by the amount of TEOS and dielectric constant of solution.