Glass transition temperature of a cationic polymethacrylate dependent on the plasticizer content - Simulation vs. experiment

Atomistic molecular dynamics simulations (NPT ensemble) are performed to compute the specific volume as a function of temperature of cationic polymethacrylate (Eudragit® RS) with varying plasticizer (triethylcitrate) content ranging from pure polymer to a plasticizer weight proportion of 7.70%. The simulated glass transition temperature of these polymer-plasticizer blends is determined as the temperature marking the kink in the slope of specific volume vs. temperature plots. A linear dependence of the glass transition temperature on the plasticizer content is found. The computational findings are supported by differential scanning calorimetry experiments showing the same trend thus validating the applied computational method.