Miniemulsion copolymerization in batch and continuous reactors

Conventional emulsion polymerization (also called macroemulsion polymerizat ion) has been widely used in a variety of industries whereas nucleation and polymerization directly in submicron monomer droplets (i.e., miniemulsion polymerization) has been primarily an academic curiosity. However, much int erest has recently been generated on the basis of the prospects of incorpor ating very hydrophobic ingredients into a water-based system via miniemulsi on polymerization. In this work, a very hydrophobic acrylic monomer, 2-ethy lhexyl acrylate, is copolymerized with methyl methacrylate using a miniemul sion recipe. The goal of this paper is to examine emulsion copolymerization kinetics for monomers of very different water solubilities. It is believed that the effects of water solubility differences between comonomers are mi nimized using a miniemulsion recipe. In this case, the copolymer compositio n is more uniform in batch miniemulsion copolymerization experiments, relat ive to batch macroemulsion copolymerizations. The same behavior is, however , not observed in a continuous-stirred tank reactor. At even moderate stead y-state conversions, there is a substantial driving force for monomer trans port that favors incorporation of the more mater-soluble comonomer.