Glass transition temperatures of poly[(methyl methacrylate)-co-(butyl acrylate)]s synthesized by atom-transfer radical polymerization

Glass transition temperatures T-g of methyl methacrylate/butyl acrylate cop olymers obtained by means of atom-transfer radical polymerization are measu red using differential scanning calorimetry. Due the nature of this polymer ization method an increase in molecular weight is produced as the reaction progresses, which gives rise to an increase in T-g. Simultaneously, a compo sition gradient with the enrichment of butyl acrylate causes a decrease in T-g. These opposite effects almost compensate each other and, therefore, no influence on the molecular weight at (M) over bar (n) < 10000 is found. Th is fact allows the application of the Johnston's equation and the Mayo-Lewi s terminal model to describe and predict the variation in T-g. with copolym er conversion for the copolymers and under the experimental conditions inve stigated.