Surface Heterogeneity\nat the Polymer–Food Interface\nInfluences Ag Migration from Plastic Packaging Incorporating Ag-Exchanged\nZeolites

Silver-enabled polymers, with their antimicrobial properties,\ncould\nprolong the shelf life and maintain quality in packaged foods. However,\nthere is limited understanding about how the Ag form in the polymer,\nfood chemistry, and other factors affect the transfer (migration)\nof Ag from the polymer to the food under the intended conditions of\nuse. In this study, we investigated the release of Ag from polymer\ncomposites (PCs) incorporating two different Ag-exchanged zeolites\n(Ag-Y), which have been explored as potential scaffolds for loading\nhigh concentrations of Ag within common polymers. We manufactured\ntwo Ag-Y films based on low-density polyethylene (LDPE): one incorporating\nionic Ag (Ag<sup>+</sup>) and one incorporating nanoparticulate Ag\n(AgNPs), each with similar initial Ag concentrations. Then, we assessed\nthe migration of Ag out of these PCs into food simulants under accelerated\nroom temperature storage conditions. In all simulants investigated,\nthe Ag<sup>+</sup>-Y/LDPE film exhibited a higher migration of Ag\ncompared to the AgNP-Y/LDPE film, suggesting a lower fraction of readily\nreleasable Ag in the latter material. Total Ag migration from AgNP-Y/LDPE\nover 10 days at 40 °C was 11.10 ± 2.05 ng cm<sup>–2</sup> of packaging surface area in water, 7.63 ± 1.59 ng cm<sup>–2</sup> in a 9 wt % aqueous sucrose solution, and 21.29 ± 1.98 ng cm<sup>–2</sup> in a commercial sweetened carbonated beverage (Squirt).\nIn contrast, Ag migration from Ag<sup>+</sup>-Y/LDPE was measured\nat 49.61 ± 3.46, 57.48 ± 9.65, and 91.54 ± 5.58 ng\ncm<sup>–2</sup> in water, sucrose solution, and Squirt drink,\nrespectively. Surface characterization techniques, including atomic\nforce microscopy (AFM), scanning electron microscopy (SEM), and conductivity\nmeasurements, revealed the presence of exposed zeolite particles at\nthe surface of the films, suggesting that direct interactions between\nAg-exchanged zeolites and food components at the simulant–polymer\ninterface play an important role in determining Ag migration from\nAg-Y/LDPE PCs.