Enhancing hydrogen separation performance through ZIF-8-incorporated PMMA–PC blend-based mixed matrix membranes

Abstract

Herein, we address the critical challenge of simultaneously enhancing permeability and selectivity in polymeric membrane-based gas separation, which is currently constrained by inherent trade-off limitations. Cubical zeolitic imidazolate framework-8 (ZIF-8) nanoparticles were prepared through a wet-chemical route, utilising hexadecyltrimethylammonium bromide (CTAB) as a surfactant to control the desired size and morphology. Nanocubes measuring approximately 150 nm were used as a filler in poly(methyl methacrylate) (PMMA) for the fabrication of mixed matrix membranes for enhanced gas separation performance. Further improvement in the performance was achieved by the polymer blending method using polycarbonate (PC) polymer. The structural, morphological, and mechanical properties of these mixed matrix membranes (MMMs) were systematically characterised. There was a 269% increase in H₂ permeability for the 7.5% ZIF-8/PMMA–PC blended MMMs, with a 51% increase in H₂/CO₂ and a 105% increase in H₂/N₂ selectivity values. These results highlight the impact of blending PMMA with PC, and ZIF-8 loading into the polymer blend, which significantly influences membrane performance, thereby underscoring the potential of ZIF-8/PMMA–PC blended MMMs in effective hydrogen separation and refinement applications.