Emulsifier-free emulsion copolymerization of styrene and sodium 1-allyloxy- 2-hydroxypropane sulfonate

Colloidal particles of poly(styrene-co-sodium 1-allyloxy- 2-hydroxypropane sulfonate) with diameters of 508 ∼ 596 nm were synthesized by emulsifier-free emulsion copolymerization, crosslinked with divinylbenzene, and initiated by potassium persulfate/sodium bisulfite in a mixed solvent of water and acetone. The diameters of the submicrometer-sized particles were measured by dynamic light scattering (DLS) and scanning electron microscopy (SEM). The surface charge densities of the particles were determined by condutometric titration. The results showed that the highly surface charged monodispersed submicrometer-sized particles were obtained by two-stage shot growth polymerization. The particle diameters could be reduced and controlled by adding suitable amount of acetone.