Preparation and characterization of oligomeric terpolymers of styrene, methyl methacrylate and 2-hydroxyethyl methacrylate: A comparison of conventional and catalytic chain transfer

Batch solution terpolymerizations of styrene, methyl methacrylate and 2-hydroxyethyl methacrylate were carried out at 70°C in the presence of either dodecanethiol or bis[(difluoroboryl)diphenylglyoximato]cobalt-(II) (COPhBF), to yield polymer products with a number average molecular weight of about 2500. Conversion, molecular weight distribution and overall composition were monitored during the reaction, and the final products were investigated using differential scanning calorimerry and thermogravimetric analysis. It was found that the overall rates of polymerization do not differ significantly in the two systems, but that the molecular weight distribution of the polymer formed in the presence of the thiol becomes increasingly broader during the polymerization, whereas the COPhBF-mediated polymerization produces a relatively uniform product during the course of the reaction. The polymer product formed with COPhBF was found to be slightly less thermally stable than the product formed by the thiol, which can be explained by the formation of unsaturated endgroups in the case of the former product.