Process parameters and their effect on grafting reactions in core/shell latexes

Abstract The grafting of methyl methacrylate (MMA) onto polybutadiene (PB) latexes prepared by seeded emulsion polymerization at 50°C was investigated as a function of: (a) initiator concentration used in the secondary polymerization, (b) monomer‐to‐polymer ratio, (c) the specific surface area of the seed latex, and (d) the degree of conversion. The thin layer chromatography/flame ionization detection (TLC/FID) technique was used to determine the proportion of graft copolymer in the core/shell latex, It was found that grafting PMMA onto PB depended upon the concentration of initiator, decreasing as the concentration was increased. The amount of grafting increased with increasing specific surface area of the seed latex, while the molecular weight of the acetone‐soluble graft copolymer decreased. The amount of graft copolymer was found to decrease concurrently with increasing monomer‐to‐polymer ratio and degree of conversion. These results suggest a hydrogen abstraction mechanism in the formation of graft PB–PMMA through a chain transfer process.