Ternary Phase Field Model and Characterization of Water/nmp/polysulfone Membrane Prepared by Non-Solvent Induced Phase Separation

A ternary phase field model is developed for water/N-methyl-2-pyrrolidone(NMP)/polysulfone system to simulate the non-solvent induced phase separation process. Our model succeeds to predict detailed asymmetric membrane structures, with dense skin layer and porous sublayer constructed from polymer network. It is found that the pore distribution and connectivity of polymer network change with the initial composition of casting solution and coagulation bath. Tortuosity and maximum pore size along the direction of thickness are calculated, with a typical trade-off relation found between them. Electrochemical separation performance was evaluated and found to have a notable correlation with structural characteristics.