Engineering gas-permeable MOF/polymer interfaces in mixed-matrix membranes for advanced CO2 separation

Interfacial compatibility is a critical prerequisite for maximizing the gas separation pot entail of metal-organic framework (MOF)-based mixed-matrix membranes (MMMs). In this study, an innovative strategy that employs polymers of intrinsic microporosity (PIMs) covalently grafted onto MOF surfaces has been introduced to engineer compatible interfaces through graded interfacial bonding. Through the reaction between PIM-COCl functionalized polymers and ZIF-NH 2 nanoparticles at ambient temperature, amide-bonded PZIF-CONH nanohybrids have been synthesized, which exhibited superior dispersibility in both solvent media and polymer matrices. Notably, the PZIF-CONH nanohybrids retained their intrinsic high porosity without encountering the pore-blocking issues commonly associated with conventional surface modifiers, owing to the microporous nature of PIM materials. The PIM-based surface modification establishes strong interfacial interactions between ZIF-particles and the polyimide matrix, leading to the fabrication of defect-free MMMs. These gas separation membranes have demonstrated significantly enhanced CO 2 permeability and CO 2 /CH 4 selectivity, exceeding the 2008 upper bound. The gas-permeable polymeric modification approach can offer a promising solution for enhancing the stability and separation performance of MMMs.