PREPARATION OF MONODISPERSE CROSS-LINKED POLYSTYRENE MICROSPHERES BY COMBINING DISPERSION POLYMERIZATION WITH HYDROTHERMAL PROCESS

Cross-linked monodisperse polystyrene microspheres were synthesized using one-step method by combining dispersion polymerization with hydrothermal process using styrene as monomer, AIBN as initiator, PVA as stabilizer and ethanol and deionized water as solvent in this paper. The cross-linked monodisperse polystyrene microspheres could be prepared in a large alcohol-water range, even if the crosslinking agent was up to 2 wt%. We focused on the system that the ethanol/water ratio of solvent was fixed at 50/50, to study the effects of stabilizer type and content, organic phase content, initiator concentration and autoclave fill volume on the morphology of the microspheres and size distribution. It was found that the microspheres showed coalescence with decreasing the molecular weight and increasing content of stabilizer. Even without any stabilizers the monodisperse crosslinked PS microspheres could still be prepared when high content crosslink agent was used. The microspheres showed polydispersity gradually with the organic phase increasing. The content of the initiator and the fill volume in the autoclave have little effect on the morphology of the microspheres. And the cause and mechanism of the one-step preparation method of monodisperse crosslinked polystyrene microspheres were also discussed.