Preparation of <scp>PET</scp> / <scp>PE</scp> Bilayer Film From Recycled Waste Plastic Bottles: Synergistic Achievement of Radiation Cooling and Mechanical Toughness

ABSTRACT This study proposes a recycling strategy utilizing waste plastic bottles (PET bottle bodies and PE caps) to successfully fabricate a bilayer composite film, PET/(PE–TiO 2 ), which exhibits excellent passive radiative cooling performance and enhanced mechanical properties. The upper layer, consisting of highly reflective PET nanofibers fabricated via electrospinning, achieves a high solar reflectance (&gt; 96%) across the solar spectrum (0.3–2.5 μm). The lower layer, a PE–TiO 2 composite prepared by melt blending, enhances the overall mechanical strength of the material. Systematic characterization demonstrates that the PET/(PE–TiO 2 ) bilayer film maintains high optical performance while significantly improving mechanical strength (breaking strength increased by &gt; 5‐fold) and thermal stability (decomposition temperature &gt; 400°C). Both theoretical calculations and experimental validation confirm that the material achieves a net cooling power exceeding 100 W/m 2 under standard solar irradiation (1 kW/m 2 ). Practical applications demonstrate surface temperature reductions of approximately 10°C for the human body and 5.3°C for electronic devices. This work not only achieves efficient synergistic recycling and value‐added utilization of PET and PE but also provides a new approach for developing low‐cost, high‐performance, and environmentally friendly passive cooling materials, with broad application prospects in personal thermal management, electronic thermal regulation, and building energy efficiency.