Multifunctional porous polymeric film with radiative cooling and antimicrobial properties for sustainable food preservation

Abstract

Over 30% of global food is lost annually during transit and storage, primarily due to solar irradiation, heat accumulation, and microbial proliferation. Conventional fossil plastic packaging inadequately protects against these threats and exacerbates environmental pollution. Consequently, there is an urgent need for sustainable packaging materials that can simultaneously reflect solar radiation, provide effective cooling under solar irradiation, and inhibit microbial growth. Herein, we report a multifunctional porous packaging film fabricated via a facile single-step casting method using cellulose acetate as the sustainable polymer matrix, with ethylene glycol (EG) as a plasticizer and polyhexamethylene guanidine (PHMG) as an antimicrobial agent. The film spontaneously develops a porous architecture that enables passive radiative cooling, achieving high solar reflectance (>80%) and strong mid-infrared emissivity (>90%) within the atmospheric window. Under solar irradiation, the porous film exhibited average temperature reductions of 17.3 °C, 14.8 °C, and 4.7 °C relative to the reference, CA film, and white paper, respectively, thereby reducing heat accumulation within the packaged food. Concurrently, the incorporation of PHMG endows the film with nearly 100% antibacterial efficacy. Additionally, the film demonstrates exceptional ultraviolet blocking (~100%) and notable antioxidant capabilities. Practical tests confirm the film effectively prevents thermal damage in fresh grapes, inhibits bacterial growth on meat, and delays mushroom browning. By synergizing radiative cooling, antibacterial action, ultraviolet shielding, and antioxidation, this strategy offers a promising pathway for next-generation sustainable food packaging.