A tunable mixture solvent for poly(ɛ-caprolactone): Acetone + CO2

A unique contribution of the present paper is the comparison of compressibility and expansivity of the solutions with the corresponding properties of the solvents. Analysis of the data shows that the compressibilities of PCL solutions are lower than that of the acetone + carbon dioxide solvent mixture at temperatures lower than 373 K. At around 373 K, compressibilities become equal to each other and a switchover is observed at higher temperatures. The difference in the isothermal compressibility of the polymer solution and the solvent decreases with pressure, but reaches a plateau value for pressures greater than 25 MPa. Compared to their solvent mixture, the polymer solutions display a higher isobaric expansivity at the same pressure.