PARTIAL AND SATURATION SWELLING IN LATEX-PARTICLES OF POLYBUTADIENE, STYRENE METHYL-METHACRYLATE COPOLYMERS AND COMPOSITE-PARTICLES

Partial and saturation swelling experiments in latex particles of styrene methyl methacrylate copolymers, polybutadiene and composite particles containing polybutadiene with styrene and methyl methacrylate grafted were performed with the centrifugation method. Very good agreement is achieved between the experimental results of partial swelling and a simplified theoretical model, The behaviour of monomer partitioning when no monomer droplets are present is independent of polymer type, polymer crosslinking and latex particle diameter. The saturation monomer partitioning experiments also showed good agreement with a simplified thermodynamic theory. The polymer type does not influence the ratio of two monomers (styrene and methyl methacrylate) in the particle and droplet phases. Also, there is no preferential solvation of styrene in polybutadiene. This is an important result for the graft polymerization of styrene and methyl methacrylate. Differences observed in copolymer composition between graft and free copolymers thus cannot be ascribed to monomer partitioning.