Microemulsion polymerization. 3. Molecular weight and particle size distributions

Molecular weight and particle size distributions of latexes prepared by fre e radical polymerization of n-butyl methacrylate, tert-butyl methacrylate, n-hexyl methacrylate, and styrene in aqueous microemulsions of dodecyltrime thylammonium bromide surfactant are measured using GPC/MALLS, QLS, and cryo -TEM. The results are compared to a molecular weight distribution model der ived from the monomer partitioning and kinetic studies described in the acc ompanying papers. Polystyrene with weight-average molecular weights of simi lar to 15 x 10(6) Da, which are 7 times greater than the limiting molecular weight imposed by chain transfer to monomer, are consistently obtained. Di ffusion-limited exit of monomer radicals, generated by chain transfer, to t he aqueous phase coupled with chain transfer to polymer are likely reasons for the enhanced polystyrene molecular weights.