Postmodification of UiO-66-NH₂ Enhances the Interfacial Interaction of Mixed Matrix Membranes for Efficient CO₂/N₂ Separation

MOFs-filled mixed matrix membranes (MMMs) have great potential to break the trade-off effects of traditional gas separation membranes. However, achieving good interfacial compatibility and adequate dispersion of the MOF is not straightforward. In this study, a continuous postmodification was developed for advanced CO 2 /N 2 MMMs. UiO-66-NH 2 was easily modified with trimesoyl chloride (UiO-66-TMC) and polyethylene glycol (UiO-66-PEG) sequentially, which was utilized as fillers to construct polyimide (PI) mixed matrix membranes (MMMs). Rich interactions between modified UiO-66-NH 2 and the PI polymer contribute to efficient CO 2 and N 2 separation. At 25 °C and 0.1 MPa, UiO-66-TMC/PI MMMs showed a CO 2 /N 2 selectivity of 55.3, and a CO 2 permeability of 616.17 Barrer, and those are 56.7 and 686 Barrer for UiO-66-PEG200/PI MMMs. Both of their CO 2 /N 2 separation performances exceed the 2008 Robeson upper bound. The ether bonds in PEG exhibit strong interactions with the CO 2 molecules and improve the CO 2 dissolution selectivity. Meanwhile, the introduction of organic ingredients realized good dispersion and interfacial compatibility within the PI matrix. This work lays the groundwork for the further fabrication of highly selective CO 2 separation materials with specific microscopic interface structures and properties.