Phase Behavior and Ternary Diagram Construction for Membrane Forming Polycarbonate Solutions

Cloud points at different polymer concentrations were obtained by the simple titration method and compared with the numerically calculated theoretical binodal curves for Polycarbonate/Dimethylacetamide/Water (PC/DMAc/Water) and Polycarbonate/N-Methyl-2-pyrrolidone/Water (PC/NMP/Water). The interaction parameters for solvent polymer and nonsolvent polymer were obtained from Hansen's solubility parameters. The cloud points determined were found to be in close agreement with the theoretical binodal curve calculated. Coagulation values for different solvents such as Dichloromethane (DCM), Dimethylacetamide (DMAc),N-Methyl-2-pyrrolidone (NMP) and Tetrahydrofuran (THF) were also determined and the results were plotted in a ternary diagram to realize the effect of interaction parameters on the coagulation values. The higher the mutual affinity of solvent to polymer (low χ23), the faster is the liquid-liquid demixing rate to occur. For DCM solvent, fastest demixing rate was exhibited and lowest for the THF.

Phase Diagram of an Aqueous Salt-Polymer System Composed of Poly Ethylene Glycol 4000 + Na3C6H5O7+ H2O

Liquid−liquid extraction for the poly ethylene glycol (PEG) + Na3C6H5O7 + H2O system, with PEG of molecular weight 4000, have been measured at 300.15 K. Phase diagram behavior and tielines for PEG4000 have been studied and the effects of molecular weight of PEG 2000,4000,6000 on the binodal curve was investigated. In comparing to literature it was found that an increase in molecular weight of PEG shifted the binodal curve to lower PEG and salt concentrations. The ATPS's studied may be used in separation of protein and other compounds.