Phenolic Resin‐Functionalized NH ₂ ‐UiO‐66‐Containing Mixed Matrix Membranes for CO ₂ /CH ₄ Separation

For mixed matrix membranes (MMMs), the inherent structural features and composition of the embedded nanofillers play a pivotal role in governing their overall performance. In this work, phenolic resin‐functionalized RF in @NH 2 ‐UiO‐66 nanofillers were prepared through an in situ approach that combined the growth of NH 2 ‐UiO‐66 with the polymerization of resorcinol and formaldehyde. The resorcinol–formaldehyde polymerization process effectively accelerated MOF nucleation, resulting in smaller MOF particles with improved dispersion within the MMM. The interfacial interactions between the phenolic resin and the polyetherimide (PEI) matrix provided excellent interfacial compatibility. Furthermore, the phenolic resin with its high CO 2 adsorption capacity improved the overall CO 2 adsorption capacity of the functionalized MOF, which is conducive to the realization of high CO 2 permeability of MMM. Compared to the pristine PEI membrane, the 30‐RF in @NH 2 ‐UiO‐66‐PEI MMMs containing phenolic resin‐functionalized MOF nanofiller demonstrated a significant improvement in the CO 2 permeability, reaching 8505 Barrer (an approximately 110‐fold increase compared with the pristine PEI membrane) and 17.7 in the CO 2 /CH 4 selectivity. These results confirm that the separation performance of the PEI membrane could be remarkably improved with the addition of RF in @NH 2 ‐UiO‐66.