Seeded semicontinuous emulsion copolymerization of butyl acrylate with cross-linkers

The seeded semicontinuous emulsion copolymerization of butyl acrylate (BA) with divinyl monomers (butanediol diacrylate, BDA, and allyl methacrylate, AMA), at 80degreesC and using potassium persulfate as initiator was investigated. Particularly, the study of the influence of the type and amount of cross-linkers on the kinetics, level of branching, cross-linking density, gel fraction, sol molecular weight, and latex film mechanical properties (i.e., glass transition temperature, T-g, storage modulus, and molecular weight between entanglements, M-e) produced during the polymerizations was considered. The results showed that the most reactive cross-linker, BDA, produced the less cross-linked, branched, and gel-containing polymer. Mechanical property data confirmed this unexpected trend as the copolymer made with BDA exhibited the weakest mechanical properties. These results were explained by the higher occurrence of primary cyclization reactions in the case of BDA.