The design and performance research of PTFE/PVDF/PDMS superhydrophobic radiative cooling composite coating with high infrared emissivity

High infrared emissivity in the atmospheric transparent spectral band, high reflectivity in the solar radiation band, self-cleaning and no heat treatment process are crucial for the application of the radiative cooling materials. In this work, a superhydrophobic radiative cooling composite coating was facilely prepared by using two sizes of polytetrafluoroethylene (PTFE) particles as main fillers and silica (SiO2) nanoparticles as auxiliary fillers, and polydimethylsiloxane (PDMS) and polyvinylidene fluoride (PVDF) as binders. The coating can be scraped onto the substrate through a scraper without any heat treatment procedure. The water droplet contact angle (WCA) and rolling angle (SA) of the coating can reach a maximum of 158 ± 0.5° and a minimum of 3 ± 0.3°, respectively. The average reflectance of the coating in the visible spectral band was around 90.6%. The average infrared emissivity of the coating in 8 ~ 13 µm spectral band was about 0.989. The test results show that the coating has excellent self-cleaning and cooling properties. Furthermore, the coating also exhibits good abrasion resistance, preferable adhesion performance, ultraviolet radiation resistance, high temperature stability, self-cleaning and anti-icing performance.