Composite film with tunable gas permeability and temperature-responsive release for postharvest preservation

The quality deterioration of perishable produce is accelerated by the elevated temperature and imbalanced gas composition. Herein, a multifunctional composite film (Eugenol@PNPMs@HACC-g-PAA, EP@HP) integrating temperature-responsive antimicrobial and gas regulation was developed for smart and precise freshness preservation. The film achieved an exceptional CO 2 /O 2 selective permeability ratio of 5.58 gas at 25°C by introducing eugenol-loaded aminated porous poly(lactic acid) microspheres into the polymer matrix. The phase transition temperature was precisely controlled at 25 ℃ by adjusting the molar ratio of quaternary ammonium groups to acrylic monomers, which realized the responsive antimicrobial release under elevated temperatures. Antimicrobial tests showed that EP@HP possessed more than 80 % antibacterial properties against key postharvest pathogens ( Escherichia coli , Staphylococcus aureus , and Botrytis cinerea ). Furthermore, the film exhibited antifogging properties, UV-blocking properties, mechanical strength, and biocompatibility. More importantly, storage tests demonstrated that the film extended the shelf life of bananas and kiwifruit by 3 and 9 days, respectively, through synergistic gas regulation and microbial suppression. This work presents a multifunctional smart film that combined autonomous gas regulation with on-demand antimicrobial release, offering significant potential for industrial applications according to its convenient fabrication process and effective preservation performance.