An environmentally friendly porous PDMS film via a template method based for passive daytime radiative cooling

Passive daytime radiative cooling (PDRC) is a green and energy-free passive cooling method by reflecting sunlight and radiating heat into the cold outer space through atmospheric transparent windows (ATW). High reflectivity and high emissivity are two vital factors affecting the cooling performance. In this work, an environmentally friendly porous polydimethylsiloxanes (PDMS) radiative cooling film was fabricated, which has 73.3 % solar reflectance (0.3–2.5 μm) and 99.7 % infrared emissivity (8–13) μm. Thus, the sample displayed a remarkable PDRC property by yielding an average temperature drop of 18.7 ℃ compared to the sub-ambient temperature at the solar intensity of 769 W/m2. At the same time, the film with hydrophobicity (132.92°) can decrease pollution caused by dust, which is significant for prolonging life and maintaining the performance of these films. This technique is simple and economical, and has the prospect of large-scale commercial application.