ZIF-67-Hmim-PDMS-PEO/pebax mixed matrix membranes: enhanced CO2 separation performance through interfacial design and synergistic effects
With the escalating environmental challenges posed by CO 2 emissions, particularly the greenhouse effect, the development of efficient CO 2 utilization and storage technologies have become critically important. The mixed matrix membranes (MMMs) have emerged as promising candidates for gas separation due to their superior permeability and selectivity. However, practical applications are often hindered by issues such as nanoparticle agglomeration and poor compatibility between fillers and polymer matrices. In this study, a pre-assembly strategy was proposed. Through 2-methylimidazole (Hmim) served as a molecular bridge connecting the ZIF-67 with the polydimethylsiloxane-poly(ethylene oxide) (PDMS-PEO) block copolymer, the ternary ZIF-67-Hmim-PDMS-PEO nanofluid was constructed, which was subsequently blended with Pebax1657 to fabricate high-performance MMMs for CO 2 separation. Comprehensive characterization of the ZIF-67-Hmim-PDMS-PEO/Pebax1657 MMMs was conducted using SEM, XRD, FTIR, TGA, and DSC techniques. The results demonstrated that the ternary blending strategy involving ZIF-67, Hmim, and PDMS-PEO not only significantly enhanced the dispersion stability of ZIF-67 nanoparticles but also improved their compatibility with the polymer matrix. Remarkably, the incorporation of ZIF-67-Hmim-PDMS-PEO nanofluid led to substantial improvements in CO 2 permeability while maintaining selectivity. The membrane with 20 wt% ZIF-67-Hmim-PDMS-PEO demonstrated CO 2 /N 2 selectivity significantly surpassed that of the membrane prepared without pre-assembly. The membrane containing 30 wt% nanofluid exhibited a 235% enhancement (343.0 Barrer) in CO 2 permeability compared to pristine Pebax1657 membranes, with the selectivity of 51.2, reaching the 2008 upper bound for CO 2 /N 2 separation. These findings highlight the effectiveness of our approach in addressing key challenges in MMMs development for advanced gas separation applications.
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