Preparation of raspberry-like PSt/SiO2 organic-inorganic nanocomposite microspheres through Pickering emulsion polymerization

Polystyrene/SiO2 composite microspheres were successfully prepared by Pickering emulsion polymerization using a cationic azo initiator (2, 2′-azobis (isobutyramidine) dihydrochloride (AIBA)) in combination with a commercially available glycerol-functionalized ultrafine aqueous silica sol in the absence of any auxiliary comonomer. Transmission electron microscope (TEM) indicates polystyrene/silica particles with raspberry-like morphology. The particle sizes and final silica content range from 190 nm to 300 nm and 28% to 44%, respectively. The influences of initial silica content, AIBA content, reaction temperature on the average diameters and silica contents of the composite microspheres were studied. The result indicates that with the initial silica content increase, the diameter of the composite microspheres tends to decrease and the silica contents adsorbed on the latexes surface increase. The silica content increases with the increase of the AIBA amount. With the reaction temperature increase, the average diameter increases, but the variance of silica content is less.