Preparation of Monodisperzed Polystyrene Microspheres by Dispersion Polymerization

The Polystyrene microspheres(PST) were prepared by dispersion polymerization of styrene(ST) in a mixture of ethanol and deionized water,using azodiisobutyronitrile(AIBN) and polyvinylpyrrolidone(PVP) as the initiator and stabilizer,respectively.The affected factors on microsphere diameter,size distribution,and the yield were discussed.The results showed that the optimal polymerized conditions were as follows:the concentrations of the monomer was 45-50wt.%,that of AIBN was 3wt.%,concentration of stabilizer PVP was 1.5～2wt.%,the ratio of ethanol and water was 10:1,the reaction temperature and time was 95℃ and 12h,respectively.On this condition,the average size of as-prepared microspheres was 5μm with excellent dispersion,narrow size distribution,and 95% high yield.The comparing analyses of the SEM morphologies before and after the centrifugal PST microspheres certified that PVP molecules existed on the surfaces of PST microspheres in the form of physical absorption.