Controlled Release of Antimicrobial ClO₂ Gas from a Two-Layer Polymeric Film System

We report a two-component label system comprising a chlorite-containing polymer film and an acid-containing polymer film that can release antimicrobial ClO₂ gas upon adhering the two films together to enable a reaction of the chlorite and acid under moisture exposure. The chlorite-containing film comprises a commercial acrylate-based pressure-sensitive adhesive polymer impregnated with sodium chlorite. The acid-containing film comprises a commercial poly(vinyl alcohol) polymer loaded with tartaric acid. Both of the films were prepared on low ClO₂-absorbing substrate films from stable aqueous systems of the polymers with high reagent loading. Rapid and sustained releases of significant amounts of ClO₂ gas from the label system were observed in an in situ quantification system using UV-vis spectroscopy. It was found that the ClO₂ release is slower at a lower temperature and can be accelerated by moisture in the atmosphere and the films. Controlled release of ClO₂ gas from the label system was demonstrated by tailoring film composition and thickness. A model was developed to extract release kinetics and revealed good conversions of the label system. This two-component system can potentially be applied as a two-part label without premature release for applications in food packaging.