Effect of hydrophilicity of polymer particles on their glass transition temperatures in Tthe emulsion state

The glass transition temperatures (Tg) of three kinds of poly(methyl methacrylate)-based copolymer emulsions having wide polymer compositions, which were prepared by emulsifierfree emulsion copolymerizations of methyl methacryalate with ethyl acrylate, n-buthyl methacrylate and methacrylic acid, were measured with a power compensation-type highly sensitive differential scanning calorimeter. The Tg values of the copolymers in their emulsion state (Tg E) were always lower than those in their dry states (Tg D), and the difference between Tg E and Tg D increased with an increase in copolymer hydrophilicities