Formation of polyethersulfone membranes via nonsolvent induced phase separation process from dissipative particle dynamics simulations

Dissipative particle dynamics (DPD), a coarse-grained simulation method, was used to investigate the formation of polyethersulfone (PES) membranes via the nonsolvent induced phase separation (NIPS) process with N-methyl-2-pyrrolidone (NMP) as the solvent and water as the nonsolvent coagulant. The effects of PES polymer concentration (8–16% (v/v)) and molecular weight (chain length with degree of polymerization of 60, 90, 135) on the membrane structure and morphology were investigated. The formation of asymmetric nanostructures with polymer-lean (liquid-rich) and polymer-rich domains was observed. A thin but dense polymer top layer at the liquid-polymer interface, with a more porous sub-layer, evolved over time. The effect of polymer concentration on membrane structure is more significant than that of the molecular weight of the PES polymer. As the polymer concentration increases from 8 to 16% (v/v), the surface layer becomes significantly denser, which is in agreement with experimental observations. Furthermore, high molecular weight PES leads to a slightly more porous membrane structure. •Dissipative Particle Dynamics simulations is suitable tool for studying membrane formation.•Simulations of polyethersulfone membrane formation were successfully performed.•Higher polymer concentration leads to denser membrane surface layers.•Higher molecular weight polymer leads to slightly smaller pores.•Good agreement with experimental results obtained.