Glass transition temperature of methyl methacrylate-ethyl alpha-benzoyloxymethylacrylate copolymers

Poly(ethyl alpha-benzoyloxymethylacrylate) (EBMA) and copolymers of methyl methacrylate (MMA) with EBMA have been prepared by free radical polymerizat ion. Monomer precursors of ethyl alpha-benzoyloxymethylacrylate have likewi se been polymerized. Glass transition temperatures (T-g) of homo and copoly mers have been determined by differential scanning calorimetry. The Johnsto n equation, which considers the influence of monomeric unit distribution on the copolymer glass transition temperature, has been used to explain the T -g behaviour. T-g12 has been calculated by the application of the Johnston equation, which gave a value markedly lower than the average value expected from the additive contribution of the T-g of the corresponding homopolymer s. (C) 2000 Society of Chemical Industry.