Polyurethane-based gas separation membranes: A review and perspectives

The membrane-based gas separation technique is considered one of the most environmentally benign approaches due to its low energy cost compared with conventional techniques. However, the permeability-selectivity tradeoff has been the biggest challenge in the membrane gas separation field. A variety of membrane materials with enhanced gas separation performance, mechanical strength, thermal stability, etc., have been designed. Among them, polyurethane (PU) membranes have been drawing increasing attention. Compared with those highperforming membrane materials, PUs possess relatively lower gas separation performance. However, by careful design, the performance of PU membranes could be improved. This review article is the first report to summarize the gas separation performance of reported PU membranes. The gas separation performance of pure PUs and their mixed matrix membranes (MMMs) will be summarized. Current challenges in PU-based gas separation membranes will be discussed. Several novel design routes for PU membranes will also be proposed.