Phase inversion simulation of polymer PVDF membrane based on a fluid model

Abstract

Based on the non-solvent-induced phase inversion (NIPS) membrane production process, we developed a model incorporating hydrodynamic effects and phase-field theory to simulate the phase separation process induced by concentration differences in polymer solutions. The influences of the initial polymer concentration and the composition of the coagulation bath on the film structure were studied. We found that the phase separation process starts from the top of the polymer solution layer and proceeds downwards in the layered structure. In the same system, as the initial PVDF concentration increases, the simulated morphology changes from a bi-continuous pattern to isolated droplets, thus determining the membrane morphology. Also, the validity of the model has been verified by corresponding experiments. Therefore, the model can be applied to other PVDF ternary membrane systems by modifying the material and its property parameters.