Hydrogen-Bond-Mediated Molecular Interface Engineering for High-Performance CO2 Separation Mixed-Matrix Membranes

Abstract Metal-organic framework (MOF)-based mixed-matrix membranes (MMMs) are promising for CO2 separation but remain limited by poor filler–polymer compatibility and compromised molecular sieving at high filler loadings. Herein, we developed a hydrogen-bond-mediated molecular interfacial engineering strategy by constructing complementary donor–acceptor hydrogen-bond networks between NH2-ZIF-8 and a carboxylated polyimide (COOH-PI), enabling the synergistic regulation of interfacial compatibility and the MOF pore microenvironment. The hydrogen-bonding network strengthened interfacial adhesion, suppressed nonselective defects, enhanced CO2 affinity, and optimized the ultramicroporous structure, while amination narrowed the MOF pore aperture to improve molecular sieving. The MMM containing 25 wt.% NH2-ZIF-8 with 15% amination exhibited excellent interfacial integrity and long-term operational stability, while its CO2/CH4 and CO2/N2 separation performances lie above both the 2008 Robeson upper bound and the revised 2019 upper bound reported by Neil B. McKeown et al. This strategy provides a general approach for designing high-performance CO2 separation MMMs.