An integrated materials approach to ultrapermeable and ultraselective CO₂ polymer membranes

Advances in membrane technologies that combine greatly improved carbon dioxide (CO₂) separation efficacy with low costs, facile fabrication, feasible upscaling, and mechanical robustness are needed to help mitigate global climate change. We introduce a hybrid-integrated membrane strategy wherein a high-permeability thin film is chemically functionalized with a patchy CO₂-philic grafted chain surface layer. A high-solubility mechanism enriches the concentration of CO₂ in the surface layer hydrated by water vapor naturally present in target gas streams, followed by fast CO₂ transport through a highly permeable (but low-selectivity) polymer substrate. Analytical methods confirm the existence of an amine surface layer. Integrated multilayer membranes prepared in this way are not diffusion limited and retain much of their high CO₂ permeability, and their CO₂ selectivity is concurrently increased in some cases by more than ~150-fold.