Fabrication of ZIF-loaded polymer composites with antimicrobial properties towards food packaging solutions

Microporous materials are widely explored as carriers for the controlled release of antimicrobial agents, yet their practical application requires the development of scalable and adaptable shaping processes. Metal-organic frameworks (MOFs) have the potential to exert antimicrobial effects through the release of either inorganic nodes, organic linkers, encapsulated antimicrobial agents or their combinations. In this study, the preparation and antimicrobial study of polymer-based composite films containing zeolitic imidazolate frameworks (ZIFs) on a pilot-scale are reported. Such materials are intended to be shaped for applications in food packaging. To fulfill our aim, ZIF materials have been synthesized on a large scale (>200 g scale) and fully characterized (X-Ray Diffraction, Scanning Electronic Microscopy/coupled to Energy-Dispersive X-Ray spectroscopy, thermogravimetry, low-temperature nitrogen physisorption). Structural and morphological analyses are consistent with the coexistence of two polymorphs in the large scale samples (35 wt.% ZIF-8 and 65 wt..% ZIF-dia(Zn)). Nevertheless, complementary and initial study involving pure ZIF-8 and ZIF-dia solids highlights similar antimicrobial activity for the two MOFs. Large scale samples were subsequently used for the preparation of polymer-based composite films, containing 5, 10 and 30 wt.% of ZIF-8/ZIF-dia(Zn), which were fully characterized and compared to MOF-free film. The antimicrobial disinfection studies indicate that the film with 30 wt.% MOF display significantly higher ability to inhibit Escherichia Coli growth compared to 5, 10 wt.% MOF and MOF-free formulations. Importantly, the pilot-scale process developed here is readily translatable to industrial-scale production, offering a viable route for the integration of MOF-based antimicrobial materials into commercial food packaging solutions. • Scaling up of zeolitic imidazolate frameworks preparation in aqueous media up to 200 g scale. • The two polymorphs, ZIF-8 and ZIF-dia, display similar antibacterial activities. • Pilot scale preparation of polymer-based composite films with 5-30 wt% MOF content and MOF-free film by extrusion. • Film at content of 30 wt% MOF inhibit Escherichia Coli growth (2-log unit reduction of bacterial count).