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

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 323 K and 20.0 MPa with concentrations of acetone as high as approximately 20 mol%. 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 10 mol% 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.

► Solubilities of monomers for aromatic polyimide in scCO2 with acetone were measured at 323 K.
► Entrainer effect of acetone on the solubilities of the monomers was investigated.
► Addition of about 10 mol% acetone increased ODA and PMDA solubilities by about 10- and 20-fold, respectively.
► Peng–Robinson EOS was used to predict the monomer solubilities in scCO2 with acetone.