On the Modeling of the Semicontinuous Heterophase Polymerization of Alkyl Methacrylates With Different Water Solubilities

A generalized model is presented here for the semicontinuous heterophase polymerization of methyl and hexyl methacrylate, which have very different water solubility. In this polymerization technique, neat monomer is fed at a controlled rate over a monomer-free aqueous solution of surfactant and initiator, to produce nanometer size particles with controlled molar masses, and high polymer/surfactant ratios similar to those used in conventional emulsion polymerization. For the two monomers studied at three different addition rates, model predictions accurately reproduce conversion-versus-time curves, the evolution of particle size, and the number density of particles. The model reveals that the controlling nucleation mechanism shifts from micellar to homogeneous nucleation as the monomer solubility in water increases.