Amidoxime-functionalized PIM-1 incorporating defect-engineered ZIF-8 for enhanced propylene/propane separation and plasticization resistance

Mixed matrix membranes (MMMs), composed of polymers and fillers, capitalize on the complementary strengths of both materials, offering a promising approach for developing high-performance membranes for C3H6/C3H8 separation. However, the effectiveness of MMMs is often hindered by poor interfacial compatibility between the polymer and the filler. To address this challenge, we present an effective strategy that simultaneously enhances both interfacial compatibility and gas separation performance in MMMs. By etching ZIF-8 with cyanuric acid (CA), we successfully synthesized defect-engineered ZIF-8 (DZIF-8), a hollow nanoframe structure that features open metal sites. These sites not only coordinate with the amidoxime groups of amidoxime-functionalized PIM-1 (AO-PIM-1) to improve interfacial compatibility but also significantly enhance the adsorption capacity for propylene. The resulting MMMs exhibited excellent interfacial compatibility with no observable filler agglomeration. Remarkably, the 10 % DZIF-8-based MMM enhances C3H6 permeability to 492 and boosts C3H6/C3H8 selectivity to 24. The defect-engineered MOF-based MMM (DMMM) surpassed the 2003 upper bound for C3H6/ C3H8 separation and demonstrated outstanding resistance to plasticization. Furthermore, the DMMM exceeded the 2008 Robeson upper bound for H2/CH4(N2) separation performance, highlighting its exceptional versatility. These results showcase the potential of defect-engineered MMMs in gas separation applications, particularly in high-performance C3H6/C3H8 separation.