Prediction of phase diagrams for new pH-thermo sensitive recycling aqueous two-phase systems

The recyclable aqueous two-phase systems formed by thermo-sensitive polymer (PNB) and pH-sensitive polymer (PADB) have been prepared by our laboratory. In this study, the Flory–Huggins model derived from the lattice theories and the COVE model based on the McMillan–Mayer solution theory were used for correlations and predictions of phase diagrams. The interaction parameters between the solvent and the polymers of the Flory–Huggins model were calculated from solubility parameters. The interaction parameters between the polymers and the COVE coefficients were determined by fitting experimental data. Simulation of Flory–Huggins model and COVE model indicates that the deviation between prediction values and experimental data is less than 0.50%. The COVE model was more effective than the Flory–Huggins model to this system.