The emulsion copolymerization of butyl acrylate (BA) with a trifunctional cross-linker, diallyl maleate (DAM), was investigated. The effect of the monomer feeding time and the amount of cross-linker on the microstructural properties (branching, cross-linking, gel formation, and sol MWD) of the seeded semicontinuous emulsion copolymerization of BA with DAM was investigated. It was found that the gel content was not significantly affected by increasing feeding time, but the level of quaternary carbons (an indication of the branching density) increased. On the other hand, increasing the amount of DAM in the feed composition caused gel content, level of quaternary carbons, and the cross-linking density to increase. Interestingly, the level of quaternary carbons and the cross-linking density sharply increased during the cooking period. The molecular weight of the Sol decreased as DAM increased in the feed. In addition, the effect of process type, batch versus semibatch, was also considered and important differences in the level of quaternary carbons, cross-linking, and gel content were found. (c) 2005 Wiley Periodicals, Inc.