Fabrication of sustainable radiative cooling film with superhydrophobic self-cleaning property

Radiative cooling materials can cool terrestrial objects without any energy input, but are susceptible to rain wetting and dust contamination which affects badly the cooling characteristics. Herein, this work fabricated a radiative cooling porous film with superhydrophobic self-cleaning using poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and poly (vinylidene fluoride) (PVDF). The PVDF-HFP/PVDF film consists of micropores with nanoparticles both inside and at the surface. The micro/nanostructures enhanced the scattering of solar light, which in combination with the infrared emissivity of both PVDF-HFP and PVDF polymers makes the film show excellent radiative cooling ability with a sub-ambient temperature drop of 16 degrees C. The micro/nanostructures roughened the surface of the film, which in combination with the low surface energy property of both PVDF-HFP and PVDF polymers endows the film with superhydrophobic self-cleaning property. The self-cleaning function defends the film from contamination and maintain sustainable radiative cooling for lasting applications. The integration of cooling and self-cleaning into a film paves a way to multifunctional and long-life radiative cooling materials.