Effect of reaction parameters on the dispersion copolymerization of styrene and methyl acrylate

Dispersion copolymerizations of styrene (St) and methyl acrylate (MA) (100/0 similar to 0/100 wt%) in isopropanol/water media were carried out. The poly(St/MA) latexes, containing 100/0 similar to 50/50 wt%, had a narrow size distribution in the size range of 1.3 similar to 2.0 mu m. The particle size of the poly(St/MA) latexes increased, and the molecular weight of the latex polymers decreased, upon increasing the MA content. Dispersion copolymerization of St/MA (75/25 in wt%) was also carried out to investigate the effects of various polymerization parameters on the particle size and the molecular weight of the resulting poly(St/MA) latexes. The number-average particle diameter increased upon increasing the reaction temperature and the concentrations of the monomer and AIBN initiator, and upon decreasing the concentration of PVP stabilizer and the water content in the isopropanol/H2O media. The weight-average molecular weight increased upon increasing the concentrations of monomer and steric stabilizer and the water content in the isopropanol/H2O media, but it decreased with the initiator concentration and polymerization temperature. The preferred polymerization recipes for making uniform poly(styrene-co-methylacrylate, 75/25 wt%) microparticles in size range 1.3 similar to 3.4 mu m is established.