Phase separation behavior of poly(ethylene terephthalate)/(trifluoroacetic acid/dichloromethane)/water system for wet phase inversion membrane preparation

ABSTRACT Polymeric membrane fabrication by the phase inversion technique requires substantial thermodynamics knowledge of the studied system. The objective of this work is to investigate the phase separation behavior of the poly(ethylene terephthalate) (PET)/[trifluoroacetic acid + dichloromethane (DCM)]/water system by the titulometric method, and evaluate the system characteristics aiming at membrane fabrication by phase inversion technique. The results show that the amount of nonsolvent at the cloud point decreases as the amount of DCM increases in the polymeric solution. The cloud point compositions are well‐fitted to the linearized cloud‐point curve for all studied systems, confirming that they have the required characteristics of a membrane forming system. The fabrication by wet phase inversion technique provides membranes with porous structure, thin top layer and the addition of DCM in PET casting solutions suppress the macrovoid formation. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47263.