Formation of colloidal PMMA particles via free radical and group transfer dispersion polymerization of methylmethacrylate and methylmethacrylate/ethyleneglycoldimethacrylate

Non‐aqueous dispersions of colloidal PMMA microparticles with average sizes ranging from 70 to 330 nm were prepared by living polymerization of methylmethacrylate (MMA) and methylmethacrylate/ethyleneglycoldimethacrylate (EDMA) in n ‐heptane diluent using 2‐methyl‐1‐methoxy‐1‐trimethylsilyloxy‐prop‐1‐ene (MTS) as initiator in the presence of tetrabutylammonium fluoride (TBAF) or tetrabutylammonium cyanide (TBAC) as catalyst, and polystyrene‐ block ‐poly‐(ethene‐ alt ‐propene) (SEP) as dispersing agent. The influence of process parameters such as concentrations of MMA, EDMA crosslinking agent, TBAF, and SEP on conversion, molecular weight, particle size, and molecular weight and particle size distributions has been investigated. In contrast to GTP in solution, group transfer dispersion polymerization (GTDP) was markedly slower and accompanied by agglomeration and drastic broadening of both molecular weight and particle size distributions with increasing MMA conversion. In a new GTDP process colloidal PMMA microparticles, obtained by free radical dispersion polymerization, were added as seeds, thus affording much narrower particle size distribution and high MMA conversion.