Preparation of Fe3O4/PSt magnetic particles in the presence of magnetic fluid in ethanol water mixture

Fe3O4/Polystyrene(PSt) magnetic particles with core/shell structure have be en prepared in the presence of Fe3O4 magnetic fluid in ethanol/water medium by dispersion polymerization of styrene. A Fe3O4 particle formation mechan ism was proposed. According to this mechanism, the size of particle nuclei is determined by the extent of aggregation of Fe3O4/oligomer. Magnetic part icles with diameter ranging from 5 to 200 mu m were prepared under differen t reaction conditions. Some polymerization parameters such as the concentra tion of monomer, stabilizer, initiator, and ethanol which affect particle s ize and size distribution are discussed and their effect on particle format ion are explained by the proposed mechanism.