Investigation on the membrane formation process of polymer–diluent system via thermally induced phase separation accompanied with mass transfer across the interface: Dissipative particle dynamics simulation and its experimental verification

Abstract

A new dissipative particle dynamics (DPD) simulation methodology was established to investigate the membrane formation process via thermally induced phase separation (TIPS) accompanied with mass transfer across the interface between the polymer solution and the coagulation bath, taken into account polyvinylidene fluoride–diphenyl carbonate (PVDF–DPC) system. The simulation results indicated that the polymer solution mainly underwent spinodal decomposition and if the coagulation bath medium had a good compatibility with the diluent, diluent and bath particles could engulfed or ejected across the polymer solution–coagulation bath interface, which caused a thin and dense polymer layer was formed near the interface. In addition, as the coagulation temperature decreased, the spinodal decomposition became faster and the coagulation bath had a less effect on the membrane formation process. Second as the compatibility between the diluent and coagulation bath declined the mass transfer got indistinct and the polymer layer disappeared gradually. To verify above simulation results, experiments were performed, whose conclusions were consistent with the simulations. The observation and conclusion in this study are beneficial to the understanding of the membrane formation of polymer–diluent system via TIPS.