Electrolyte effect on the particle characteristics prepared by soap-free emulsion polymerization

Monodisperse micron-sized polystyrene (PS) spheres were successfully obtained using a single stage soap-free emulsion method in aqueous media mixed with ethanol (co-solvent) containing NaCl as the electrolyte. The optimum conditions for preparing the monodisperse PS microspheres, using soap-free emulsion polymerization in a water/ethanol mixture with an electrolyte, were studied. The presence of the co-solvent and electrolyte controlled the particle dispersion stability during the polymerization. The microspheres formed using PS, with a weight-average diameter of 2.6 μm, coefficient of variation of 5.3% and zeta potential of -15.1 eV, were successfully obtained in the presence of 0.1 wt% NaCl, 10 wt% monomer, 0.1 wt% initiator and 95/5 (g/g) of a water/ethanol mixture reacted at 70°C for 24 h.