Monodisperse ultra-large-pore silica coated polystyrene core-shell microbeads via layer-by-layer assembly for nano-micro composite

Abstract

Polystyrene(PS)@SiO2 core-shell microbeads with large pore and large particle size were prepared via layer-by-layer(LBL)assembly technique for potential applications in nano-micro composites. Negative silica nanoparticles synthesized via modified Stober method and cationic poly(diallyldimethylammonium chloride)were alternately adsorbed on the surface of microbeads. Zeta potential, size, and morphology of the microbeads were monitored during LBL assembly process to ensure the successful deposition of silica nanoparticles. The porous shell was characterized using nitrogen adsorption and desorption analyses, and the surface area, volume and diameter of the pores were derived. It is found that the porous shell thickness and the pore size can be tuned by changing the coating times of silica nanoparticles. Finally, PS@SiO2 core-shell microbeads with 5,μm PS solid core and 350,nm mesoporous shell(mean BJH pore diameter is ~27,nm)were used to load CdSe/ZnS quantum dots(QDs). The fluorescence microscopic image and the optical amplification of the QDs-embedded microbeads (QDBs)indicate that the as-prepared core-shell microbeads can provide adequate space for QDs and may be useful for further application of nano-micro composites.