Solubility of polymer in the mixtures containing supercritical carbon dioxide and antisolvent

The solubilities of poly(ethylene glycol) (PEG) in the mixtures consisting of supercritical carbon dioxide (SC-CO2) and ethanol as antisolvent for PEG have been measured by observing the cloud points at 313.15 K over a pressure range up to 20 MPa. Three polymer samples with average molecular weights of 1000, 2000 and 7500 were used. It was found that PEGs have appreciable solubilities in the mixtures of SC-CO2 and ethanol. Solubilities increased with an increase in the concentration of ethanol and with a decrease in molecular weight of PEGs. And the effect of pressure on the solubility of PEG in this system is small. Furthermore, the solubilities of PEGs in the mixtures of SC-CO2 and ethanol have been correlated by a regular solution model coupled with the Flory–Huggins theory using the local composition of solvent around solute molecule.