A thermodynamic model which couples the lattice fluid theory and the Gibbs-Di Marzio criterion, which states the entropy of the system zero at the glass transition temperature, is applied to describe the sorption in presence of carbon dioxide (CO2) of polystyrene (PS), poly (methyl methacrilate) (PMMA), poly (vinyl pyridine) (PVD) and of styrene-methyl methacrilate and styrene-vinyl pyridine block copolymers. The model requires only one binary interaction parameter that successively is used to predict qualitatively the glass transition temperature (Tg) behavior as a function of the CO2 pressure. For the block copolymers, both for sorption and Tg behavior, the model evidences a continuous transition from one homopolymer to the other.
