Engineering Lithium-Magnesium Selectivity in Hydrated Polymer Membranes through Polymer Backbone Rigidity.

Using computer simulations and experiments, we demonstrate that polymer backbone rigidity can be used to tune selectivities and permeabilities of lithium over magnesium in hydrated polymer membranes. Coarse-grained molecular dynamics (CGMD) simulations suggest a strong dependence of cation diffusion coefficients on polymer segmental dynamics and cation-solvent coordination strength, with water content and backbone dynamics having distinct effects on transport properties. Experimentally, we synthesized 2-hydroxyethyl acrylate--ethyl acrylate (HEA--EA) and 2-hydroxyethyl methacrylate--methyl methacrylate (HEMA--MMA) membranes.