PREPARATION OF MAGNETIC LATEX-PARTICLES BY EMULSION POLYMERIZATION OFSTYRENE IN THE PRESENCE OF A FERROFLUID

Magnetic latex particles were prepared by the emulsion polymerization of styrene at 70-degrees-C in the presence of a commercial ferrofluid containing surfactant-stabilized magnetite particles in the aqueous ph ase or its modification by ultrafiltration, using potassium persulfate as an initiator. The effects of diversified variables such as the amo unts of initiator, monomer, and additive (calcium chloride and fluores cent dyes) on the polymerization reaction and particle characteristics were investigated. The general polymerization features were analogous to those of ordinary emulsion polymerizations. Transmission electron microscopy revealed that when the commercial ferrofluid was used the m agnetite particles localized in the latex particles and the magnetite content varied from particle to particle and that when the ferrofluid was used after ultrafiltration the magnetite particles were dispersed well in the latex particles. (C) 1993 John Wiley & Sons, Inc.