Metal-organic cages improving microporosity in polymeric membrane for superior CO2 capture.

Mixed matrix membranes, with well-designed pore structure inside the polymeric matrix via the incorporation of inorganic components, offer a promising solution for addressing CO2 emissions. Here, we synthesized a series of novel metal organic cages (MOCs) with aperture pore size precisely positioned between CO2 and N2 or CH4. These MOCs were uniformly dispersed in the polymers of intrinsic microporosity (PIM-1). Among them, the MOC-Ph cage effectively modulated chain packing and optimized the microporous structure of the membrane. Remarkably, the PIM-Ph-5% membrane shows superior performance, achieving an excellent CO2 permeability of 8803.4 barrer and CO2/N2 selectivity of 59.9, far exceeding the 2019 upper bound. This approach opens opportunities for improving the porous structure of polymeric membranes for CO2 capture and other separation applications.