Thermoplastic Polyurethane-Based Composite Film with a Hierarchical Porous Structure for Radiative Cooling and Antimicrobial Freshness Preservation

Passive radiative cooling (PRC) technology achieves cooling by reflecting solar radiation and radiating heat to cold outer space through a transparent atmospheric window (8–13 μm). In this research, we developed a porous thermoplastic polyurethane doped with MgO (PTM) film with a hierarchical porous structure via a water-solvent phase separation method, which simultaneously realizes high-performance radiative cooling (solar reflectivity of 94%, mid-infrared emissivity of 0.95) and broad-spectrum antibacterial function. It achieved an average cavity cooling effect of 14.6 °C compared to a blank group at a solar radiation intensity of 630 W·m –2, with a theoretical cooling power of 108.4 W·m –2 . Moreover, the PTM film has excellent antibacterial properties, with an inhibition rate of over 95% against Escherichia coli . The integrated dual functionality exhibits remarkable practical advantages: When applied to fresh strawberry preservation, this synergistic mechanism achieves 4–8 °C localized cooling compared with ambient conditions, effectively suppressing both enzymatic browning and bacterial growth. The treated strawberries maintained optimal freshness for at least 5 days, a significant extension compared to conventional storage. This performance is accomplished without external energy input, demonstrating the film’s potential for zero-energy cooling and hygiene maintenance in food preservation systems.