Amphiphilic Zeolitic Imidazolate Framework for Improved CO 2 Separation in PIM‐1 Mixed Matrix Membranes

This study aims to enhance the compatibility between filler and polymer in mixed matrix membranes (MMMs), addressing an important challenge in membrane development. ZIF‐94, known for its affinity to CO 2 , was partially modified with 2‐undecylimidazolate (umIm) through the solvent‐assisted ligand exchange (SALE) method to improve its compatibility with the prototypical polymer of intrinsic microporosity PIM‐1. The modified ZIF‐94 (ZIF‐94‐umIm) can be considered as an amphiphilic MOF with both hydrophilic and hydrophobic moieties, while maintaining a considerably high CO 2 adsorption capacity (2.34 mmol g −1 at 90 kPa and 0 °C). Gas separation experiments were performed using mixed gas compositions of 15/85 CO 2 /N 2 at 3 bar and 35 °C. The resulting MMM with a 5 wt.% loading exhibited an enhanced CO 2 separation performance, with ca. 70% and 10% increases in CO 2 permeability (8900 Barrer) and CO 2 /N 2 selectivity (20.2), respectively, compared to pristine PIM‐1 membranes. In addition, thin film nanocomposite membranes were prepared showing a 23.5 CO 2 /N 2 selectivity at 2350 GPU of CO 2 . This modification strategy shows a great potential for improving the CO 2 capture technologies, highlighting the potential of tailoring MOF fillers for advanced membrane materials in gas separation applications.