Measurement and prediction of the solubilities of aromatic polyimide monomers in supercritical carbon dioxide with acetone

Abstract

The solubilities of 4,4′-diaminodiphenyl ether (ODA) and pyromellitic dianhydride (PMDA), which are the representative monomers for an aromatic polyimide, were measured in supercritical carbon dioxide (scCO2) using the semi-batch flow method to clarify the entrainer effect of acetone. The investigations were carried out at 323K and 20.0MPa with concentrations of acetone as high as approximately 20mol%. Although the solubilities of both ODA and PMDA increased with increasing acetone concentrations, the entrainer effects of acetone on both monomer solubilities in scCO2 were lower than those of N,N-dimethylformamide, which was investigated in previous work. However, the addition of about 10mol% of acetone increased the solubilities of ODA and PMDA by approximately 10- and 20-fold, respectively, compared with their solubilities in pure scCO2. Moreover, the solubilities were predicted using the Peng–Robinson equation of state.