Benzyl-Induced Crosslinking of Polymer Membranes for Highly Selective CO2/CH4 Separation with Enhanced Stability

Chemical crosslinking is the most commonly used solution to address the issue of poor structure stability and low plasticization resistance of polymer membranes for gas separation. However, the general crosslinking route requires the introduction of reactive groups into the polymer chain and is very likely to weaken the separation performance of membranes. Here, we report a new and nondestructive benzyl-induced crosslinking strategy. Owing to the high reactivity and wide existence in most polymers, the benzyl-induced crosslinking could universally happen in unmodified polymer membranes. Our crosslinked polyimide membrane exhibits unprecedented performance with a CO2/CH4 selectivity > 70, three times that of non-crosslinked membranes, and with CO2 plasticization pressures above 42 bar, the highest value among the polyimide membranes reported so far. The comprehensive performance surpasses the state-of-the-art 2018 upper bound for mixed gas. Our work provides a facile and reliable route for constructing polymer membranes with highly improved stability and performance.