Batch and semibatch mini/macroemulsion copolymerization of vinyl acetate and comonomers

Three monomer systems, vinyl acetate/butyl acrylate [VAc/BA], vinyl acetate /dioctyl maleate [VAc/DOM] and vinyl acetate/n-methylol acrylamide [VAc/NMA ], with large differences in reactivity ratios and water solubilities were selected to carry out the macroemulsion and miniemulsion copolymerizations in batch and semibatch processes. Smaller particle size and greater particl e number resulted from the macroemulsion copolymerization in both of batch and semibatch processes. In batch runs, the rate of copolymerization was fa ster in the macroemulsion polymerization than in the miniemulsion process. The copolymer composition versus conversion curves in the batch and semibat ch processes were very different. The difference could be attributed to dif ferences in reactivity ratios and in the ability of various monomers to dif fuse across the aqueous phase. It is concluded that the miniemulsion copoly merization in batch or semibatch operations can compensate to some extent, for the poor monomer transport of highly water-insoluble monomers in corres ponding macroemulsion polymerizations.