Facile Fabrication of a Porous PDMS Film for Passive Daytime Radiative Cooling via the Dual Template Method

Passive daytime radiative cooling (PDRC) technology, which requires no external energy input or pollutant generation, achieves cooling temperatures below ambient levels and demonstrates immense potential for applications. High reflectivity and high emissivity are two vital factors that significantly affect cooling performance. In this study, a porous polydimethylsiloxane (PDMS) radiative cooling film (SNTP) using a dual template approach (sandpaper and NaCl template) for the first time was fabricated. The film exhibits a solar reflectance of 81.6 % (0.3 similar to 2.5 mu m) and an infrared emissivity of 99.8 % (8 similar to 13 mu m). Due to its engineered porous structure and excellent optical properties, the SNTP film demonstrates outstanding passive daytime radiative cooling (PDRC) capabilities, resulting in an average temperature reduction of 8.6 degrees C and 13.4 degrees C relative to the sub-ambient temperature under solar intensities of 420 W/m(2) and 896 W/m(2), respectively. Furthermore, the SNTP membrane was applied to various objects, including helmets, sun umbrellas, rubber seat cushions, and zinc alloy cars. Following exposure to sunlight, the covered area showed obvious cooling effect than the uncovered area. This technology features straightforward manufacturing requirements, cost-effectiveness, and significant potential for widespread commercial application.