Experimental measurements and thermodynamic modeling of the cloud point pressure for solubility of copolymers of vinyl acetate and dibutyl maleate in supercritical CO2

• The supercritical CO2-polymer systems are investigated.
• The cloud point pressures of the five CO2-copolymer systems were measured.
• The PCP-SAFT EoS was applied for prediction of the phase behavior of these systems.
• The calculated results of cloud point pressures were in good agreement with experiment.

In this study the cloud point pressure for the solubility of copolymers of vinyl acetate and dibutyl maleate in supercritical carbon dioxide were measured and modeled. The copolymers investigated have different molecular weights, with varying structures. The cloud point pressure data were modeled using the Perturbed Chain Polar Statistical Associating Fluid Theory (PCP-SAFT) equation of state (EoS) that was developed for the prediction of the phase behavior of polar polymers which are soluble in supercritical carbon dioxide (J. of Supercritical Fluids 97 (2015) 45–50). Using this model, the cloud point pressure of the polymer-supercritical CO2 systems were correlated by taking into account quadrupole-quadrupole interactions between carbon dioxide and the polymer segments through the PCP-SAFT EoS. Thus, the new parameters were determined for the copolymers studied in this work. Moreover, we applied PC-SAFT EoS for the same systems. It is shown that the results are obtained using the PCP-SAFT EoS is superior respect to PC-SAFT so that the present EoS can be applied to calculate the cloud point pressure of the copolymer-CO2 systems and the deviation of the calculated values from experiment values are low.