Fabrication of LTA zeolite core and UiO-66 shell structures via surface zeta potential modulation and sequential seeded growth for zeolite/polymer composite membranes

Zeolite-based polymer composites have garnered significant attention for their applications in separation, catalysis, and energy storage, owing to the unique properties of zeolites. The development of core–shell structures provides a promising strategy to enhance these properties, enabling the fine-tuning of zeolite characteristics within composite films. In this study, we present an innovative approach that leverages surface zeta potential differences to facilitate the growth of an organophilic metal–organic framework (MOF) on hydrophilic zeolite surfaces. Specifically, UiO-66 was successfully attached and grown on Linde Type A (LTA) zeolite particles, resulting in the formation of a robust core–shell structure (LTA@UiO-66). This core–shell architecture significantly minimized interfacial voids when embedded into a polyimide (PI, Matrimid® 5218) matrix, yielding composite films (LTA@UiO-66/PI) with superior mechanical integrity and enhanced gas-separation performance. The LTA@UiO-66/PI films demonstrated remarkable ideal selectivity for O₂/N₂ (10.7) and CO₂/CH₄ (47), outperforming traditional LTA/PI composites. These enhancements are attributed to the synergistic effects between the LTA core and the UiO-66 shell, which preserve the molecular sieving capability of the zeolite while ensuring strong adhesion and a void-free interface with the polymer matrix. The findings underscore the significant potential of zeolite-based core–shell structures in advancing industrial applications, particularly in the domains of sustainable gas separation and purification technologies.