Polyurethane-based gas separation membranes: A review and perspectives

• Pure PU gas separation membranes with different modification techniques are summarized. • PU-based mixed matrix membranes with various fillers are summarized. • Current challenges and perspectives are discussed. • The main challenge of PU-based membranes is the trade-off between gas separation performance and mechanical properties. • Chemically cross-linked MMMs and CANs provide a potential solution for developing advanced PU-based membranes. 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 trade-off 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 high-performing 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.