Highly CO₂-permeable membranes derived from a midblock-sulfonated multiblock polymer after submersion in water

To mitigate the effect of atmospheric CO₂ on global climate change, gas separation materials that simultaneously exhibit high CO₂ permeability and selectivity in gas mixtures must be developed. In this study, CO₂ transport through midblock-sulfonated block polymer membranes prepared from four different solvents is investigated. The results presented here establish that membrane morphology and accompanying gas transport properties are sensitive to casting solvent and relative humidity. We likewise report an intriguing observation: submersion of these thermoplastic elastomeric membranes in liquid water, followed by drying prior to analysis, promotes not only a substantial change in membrane morphology, but also a significant improvement in both CO₂ permeability and CO₂/N2 selectivity. Measured CO₂ permeability and CO₂/N2 selectivity values of 482 Barrer and 57, respectively, surpass the Robeson upper bound, indicating that these nanostructured membranes constitute promising candidates for gas separation technologies aimed at CO₂ capture.