Molecular simulations of liquid separations in polymer membranes

Polymer membranes are widely utilized in industrial separation processes. Along with numerous experiments conducted for gas and liquid separations, molecular simulations have also been performed to fundamentally elucidate separation mechanisms in polymer membranes. However, the simulation studies are mostly limited to gas and aqueous mixtures, and non-aqueous separations such as pervaporation and organic solvent nanofiltration are less or largely unexplored. In this review, the recent simulation studies on liquid separations in polymer membranes are critically reviewed. First, various rational design strategies to tune the performance of polymer membranes for water desalination are outlined. Then, new simulation protocols and computational characterization methods are presented for pervaporation and organic solvent nanofiltration. These bottom-up studies provide a rich landscape of microscopic insights into the separation mechanisms and processes of liquid mixtures in polymer membranes, which will facilitate the rational screening and design of high-performance polymer membranes for liquid separations.