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

Abstract 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.