“Like-Compatible-Like” Strategy for High-Performance H2-Sieving Mixed-Matrix Membranes with Intensified Filler-Polymer Interfaces

Metal organic frameworks (MOFs)-based mixed matrix membranes (MMMs) exhibit great prospects for H 2 purification. However, their further development is hindered by interfacial incompatibility and framework flexibility-induced selectivity loss. Inspired by the “like compatible like” principle, a fluorinated engineering strategy is developed by introducing isoelectronic −CF 3 groups into ZIF-9 (FZIF-9), achieving dual regulation of MOF-polyimide (6FDA-TFMB) interfaces and molecular sieving architecture. The −CF 3 functionalization synergistically enhances interfacial compatibility through dipole interactions (C═O···F−C), optimizes pore size (3.67 Å) to achieve size-exclusive H 2 /CH 4 separation. Meanwhile, it suppresses the dissolution and adsorption of CH 4 molecules by reducing the CH 4 adsorption capacity on FZIF-9 by 40% compared with ZIF-9. The FZIF-9/PI-20 wt.% MMM exhibits excellent improvements of 22.1% and 133.1% in H 2 permeability (159 Barrer) and H 2 /CH 4 selectivity (295) over ZIF-9/PI-20 wt.% MMM. Importantly, its selectivity is superior to state-of-the-art MOFs/6FDA-based MMMs, approaching the 2015 Robeson upper bound. This work establishes fluorine-mediated interface engineering as a universal strategy for advanced gas-separation membranes, particularly in H 2 /CH 4 separation.