Synthesis of core-shell latex particles of casein-g-poly(methyl methacrylate)

Synthesis of core-shell latexes of casein-g-poly(methyl methacrylate) was achieved through the graft copolymerization of methyl methacrylate onto the casein in the presence of trace copper ions. It was observed that the concentration of MMA, casein, and the ratio of MMA to casein had a prominent effect on the final conversion and graft ratio, while the concentration of copper(II) ion almost had no effect. The graft polymerization was much slower at 60°C than at 70°C. Further increase of reaction temperature from 70°C to 80°C enhanced only the initial conversion. Kinetic study of the graft copolymerization at 70°C indicated that the reaction proceeded through two stages which were typical kinetic behavior for the radical polymerization confined in a pre-formed micro-environment. Finally, the particle size of the casein-g-PMMA latexes decreased with the increase of percent grafting, and an almost linear relationship between the particle size and the percent grafting was evident.