Phase behavior of poly(L-lactide) in supercritical mixtures of dichloromethane and carbon dioxide

Phase behavior data are presented for poly(L-lactide) in supercritical mixtures of dichloromethane and carbon dioxide. Cloud point pressures were measured using a variable-volume view cell apparatus as functions of temperature, dichloromethane composition in a mixed solvent, and molecular weight of poly(L-lactide) at the polymer concentration of approximate to0.05 mass fraction in solution. This system exhibited the characteristics of lower critical solution temperature phase behavior. As the dichloromethane composition in the mixed solvent increased, the cloud point pressure at a fixed temperature decreased significantly. The cloud point pressure increased linearly with a logarithmic increase of the poly(L-lactide) molecular weight.