Highly monodispersed emulsifier-free poly(methylstyrene) (PMS) latex particles were prepared via an emulsifier-free emulsion polymerization in the presence of 2,29-azobis-(2-amidineopropane) dihydrochloride (V-50) as an initiator. A combination of kinetics and molecular weight distribution studies revealed that the polymerization followed the micellization nucleation mechanism. Results showed that an appropriate initiator concentration was necessary to obtain monodisperse and stable latex particles. Conversion of methylstyrene was found to increase significantly with increasing initiator concentrations. However, the size of PMS latex particles decreased with both the increase of initiator concentration and the reaction temperature at a constant ionic strength. The particle size was increased as the ionic strength of the aqueous phase increased, yet the variation of ionic strength had little effect on the particle size distribution. SEM micrographs showed that an agitation rate of 350 rpm or higher was required in order to produce highly monodispersed poly(methylstyrene) latex particles.

methylstyrene.PMS. latex particles in an emulsifier-free emulsion were first synthesized by using 2,29-azobis-2-amidinopropane. dihydrochlorideV-50. as an initiator. Purification of the latexes by dialysis was followed inorder to remove residual monomer, initiator and electrolytes. The cationic polymethylstyrene. latexes were then oxidized in the presence of t-butyl hydroperoxide catalyzed by copper chloride at 608C under air. The degree of oxidation increased with reaction time, but the emulsions of highly oxidized poly methylstyrene. latexes were found to be unstable. An increase of oxidant concentration enhanced the rate of oxidation, while the catalyst concentration had little influence on it. The effect of reaction temperature and pH value on the catalytic oxidation of poly methyl-styrene. latexes was also investigated.

A convenient method of preparing ultrafine poly(methylstyrene) (PMS) latex particles with aldehyde groups on the surface is developed. PMS latexes in the size range 33-81nm were prepared via microemulsion polymerization, using cetyltrimethylammonium bromide (CTAB) as surfactant. The surface of the PMS latexes was oxidized in the presence of tert-butyl hydroperoxide catalyzed by copper(Ⅱ) chloride. As the degree of oxidation increased up to 6h, the amounts of aldehyde group increased. Bigger particles were found to have a slightly higher rate of oxidation than small ones under the same oxidation conditions. The particle size underwent little change during oxidation; thus, the amounts of functional groups and the particle size could be controlled concurrently. Dialysis study of the oxidized PMS microlatexes indicated that the instability of highly oxidized PMS microlatexes was caused by the reduction of total surface charge density due to the presence of carboxylic acid groups.