Effect of Sulfonate Functional Groups on Transport and Sorption Behavior of NaCl in Disulfonated Poly(Arylene Ether Sulfone) Membranes

While current experimental theories describe bulk properties of charged desalination membranes reasonably well, little is known about the atomistic mechanisms of salt and water transport through these materials. In this study, molecular dynamics simulations of a model polymer membrane are conducted to characterize nanoscale properties and dynamics of such systems. An increase in ion pairing within the membrane is observed, which may result in larger diffusive species. Additionally, strong association of Na⁺ with sulfonate groups suggests the presence of functional group clustering, which could have significant implications for the mobility of Na⁺ within the membrane. Subsequent, more detailed analysis in these systems will be conducted to more fully understand the contribution of these behaviors to bulk properties of the material, allowing for the design of more efficient desalination membranes.