High-performance self-cleaning polymer films for passive daytime radiative cooling
Abstract
Passive radiative cooling offers a sustainable zero-energy approach for thermal regulation, which works by reflecting solar radiation and dissipating heat via atmospheric infrared radiation. It holds great promise for building energy saving and outdoor thermal management, while most existing polymer cooling films suffer from low solar reflectance, insufficient infrared emission, poor antifouling ability, and unsatisfactory flexibility. In this study, a high-performance self-cleaning polymer radiative cooling film was fabricated via a simple blending and casting method. Benefiting from optimized composition and microstructural design, the as-prepared film achieves a high solar reflectance of 90% and an infrared emissivity up to 92% within the atmospheric window. Outdoor rooftop tests demonstrate that the film can reach a maximum cooling temperature drop of 4.6 °C under daytime sunlight, with an average cooling amplitude of 2.18 °C. Besides, the film exhibits excellent hydrophobic self-cleaning performance and good mechanical flexibility, which can effectively prevent dust contamination and adapt to curved surfaces for practical installation. This work provides a facile route to prepare multifunctional polymer films with superior optical cooling performance, self-cleaning capability, and flexibility, showing bright application prospects in passive cooling and building thermal management.