Fabrication and self-assembly of colloidal crystals of core-shell hybrid particles

Abstract

Monodisperse silica nanoparticles (SiNP) with different diameters ranging from 40-390 nm were prepared by the hydrolysis of tetraethyl orthosilicate (TEOS) in an alcoholic solution. Incorporation of diethoxydimethyl silane into the condensation of TEOS yielded smaller particles of size ~20 nm. The effect of the reagent concentration, reagent addition sequence and method of mixing on the size and morphology of silica nanoparticles were investigated. The surface functionalization of SiNP was successfully achieved by covalently binding the trimethoxy groups of a chain transfer agent (EHT) onto the SiNP. The surface-modified SiNP were used to mediate reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene (S), methyl methacrylate (MMA) and methacrylate (MA) by the “grafting from” approach to form core-shell hybrid particles with high polymer grafting density. A facile and straightforward approach was used to self-assemble two-dimensional (2D) arrays of colloidal crystal film of SiNP-PMMA hybrid particles. Additionally, the precise control obtained over particle size allowed the self-assembly of 3D colloidal crystals of core-shell SiNP-PS following fast and facile processes, based on the use of centrifugational forces and dispersion forces.