Amino-ionic liquid-assisted highly compatible mixed matrix membranes of ZIF-8 and PIM-1 for efficient CO2/N2 separation

Abstract

Mixed matrix membranes (MMMs), which incorporate metal–organic framework (MOF) nanofillers within a polymer matrix, offer a highly promising solution for CO₂ capture and separation. However, poor interfacial compatibility and filler aggregation in MMMs pose significant challenges to enhancing CO₂/N₂ separation performance. Here, we present a novel approach using amino-ionic liquid modification to optimize MMMs, where the modified AFIL promotes the formation of ZIF-8 with well-defined facets and sharp edges and enhances the compatibility between ZIF-8 particles and PIM-1 polymer matrixes for favorable CO₂ affinity and selective CO₂ transport. The resulting 10 wt% AFIL@ZIF-8/PIM-1 exhibits exceptional gas separation performance with a CO₂ permeability of 7864 ± 262.2 Barrer and a CO₂/N₂ selectivity of 29.66 ± 1.96. More importantly, the incorporation of AFIL into the ZIF-8 pores significantly enhances the thermal stability and aging resistance of AFIL@ZIF-8/PIM-1 MMMs via structural support and hydrogen bonding interactions. This work provides a practical approach for developing hybrid membranes for CO₂/N₂ separation, showcasing improved overall performance and strong interfacial compatibility.