Effect of the diacrylate ester size on the semicontinuous cross-linking emulsion copolymerization of BA

The seeded semicontinuous emulsion copolymerization of butyl acrylate (BA) with a series of diacrylate cross-linkers at 80 degrees C and using potassium persulfate as initiator was investigated. The influence of the diacrylate ester size on the kinetics, branching and cross-linking density, molecular weight between entanglements, gel fraction, sol molecular weight, and mechanical properties (glass transition temperature and storage modulus) was investigated. It was found that the shorter the diacrylate, the less cross-linked the polymer and the lower the glass transition temperature and the storage modulus. This effect was explained by a higher cyclization rate of the shorter diacrylates due to energetically favored cycle formation.