In‐Situ Formation of Three‐Dimensional Network Intrinsic Microporous Ladder Polymer Membranes with Ultra‐High Gas Separation Performance and Anti‐Trade‐Off Effect

Abstract The global quest for clean energy and sustainable processes makes advanced membrane extremely attractive for energy‐intensive industrial gas separations. Here, we disclosed a series of ultra‐high‐performance gas separation membranes (PIM‐3D‐TB) from novel network polymers of intrinsic microporosity (PIM) that combine the advantages of solution processible PIM and small pore size distribution (PSD) of porous organic polymers (POP), which was synthesized by in situ copolymerization of triptycene‐2,6‐diamine as linear part and triptycene‐2,6,13(14)‐triamine (TTA) as crosslinker. The resulting PIM‐3D‐TB membranes demonstrated outstanding separation properties that outperformed the latest trade‐off lines for H 2 /CH 4 and O 2 /N 2 . They also showed an anti‐trade‐off effect by simultaneously enhancing gas permeability and gas‐pair selectivity with increasing TTA content. The TTA crosslinking node increased the microporosity, and, shifted the PSD from the ultramicropore (<7 Å) toward the more size sieving submicropore (<4 Å) region. The post‐treated TTA‐75 displayed an exceptional H 2 permeability of 8000 Barrer and H 2 /CH 4 selectivity of 208. These PIM‐3D‐TB membranes and their design protocol have unparalleled potential in the next generation of membranes for hydrogen purification and air separations.