Interfacial fusion engineered fluorinated UiO-66-based mixed matrix membranes: Enhanced He/CH4 separation

Metal organic frameworks (MOFs)-based mixed matrix membranes (MMMs) exhibit great prospect for He/CH 4 separation. However, it is still restricted by interfacial incompatibility-induced low filler loading and selectivity loss. This study proposed an interface fusion strategy by 6FDA-TFMB (PI) functionalized CF 3 -UiO-66 through NH 2 -UiO-66 bridging to achieve dual regulation of interface compatibility and molecular sieving. Crucially, this interface fusion strategy allowed a substantial increase in filler loading to 20 wt%, representing a 100% improvement over unfunctionalized CF 3 -UiO-66. The covalent bond formed between the amino group and the dianhydride improved the interfacial compatibility. The –CF 3 group on the UiO-66 reduced the pore size of UiO-66 and weaken the adsorption of CH 4 . The dual synergistic effect made the resultant MMMs exhibited excellent He permeability (165.2 Barrer) and He/CH 4 selectivity (394.1), representing improvements of 81.14% and 319.7%, respectively, compared with pristine 6FDA-TFMB membrane, approaching to the 2008 Robenson upper bound, surpassing most of the reported PI based membranes for He/CH 4 separation. This synergistic architecture not only validated the interface fusion engineering but also provided a foundation for designing efficient He/CH 4 separation materials with tailored microscopic properties.