Characterization of polystyrene latexes

Abstract

Polystyrene latexes were prepared by emulsion polymerization. Styrene was used as monomer, potassium persulfate was the reaction initiator and sodium hydrogen carbonate was used as buffer. Surfactant may or may not be used. Three types of surfactant, ie sodium dodecylbenzene sulfonate (anionic), Triton X-100 and Vulcastab LW (nonionic), and hexadecyltrimethyl ammonium bromide (cationic), were used. The prepared latexes were characterized according to concentration, density, pH, ionic strength, particle size, particle size distribution and surface charge. For prepared latexes with anionic surfactant, the effects of temperature, initiator concentration, surfactant concentration and amount of monomer on the latex size were investigated. Scanning electron microscopy was used as a tool for latex characterization. The results show that by increasing temperature, initiator and emulsifier concentration, the latex diameter decreases. However, size increases by increasing the amount of monomer. A potentiometric titration technique was employed for determination of surface charge. It was found that for all latexes, surface charge densities are in the same range. © 2000 Society of Chemical Industry