Long-lasting self-cleaning daytime radiative cooling paint for building

Endowing the building exterior wall with superhydrophobicity and radiation cooling function can not only achieve building energy conservation, but also significantly reduce the cost of manual cleaning, so as to ensure the efficiency and durability of the radiant cooling function of the building exterior wall. However, it is still a challenging work to make coatings (paint films) with the above two functions on the surface of large external walls. Herein, we have developed a polyvinylidene fluoride/polydimethylsiloxane (PVDF/PDMS) composite coating composed of PVDF particles and PDMS binder, which is prepared by one-step brushing method. It exhibits solar reflectivity of 90.6%, infrared emissivity of 98.1%, contact angle of 158.2 degrees and rolling angle of 7.9 degrees. The PVDF/PDMS coating exhibits a radiative cooling temperature of 4.93 degrees C under direct solar irradiation. Importantly, both the DRC function and the superhydrophobicity of the PVDF/PDMS film exhibit excellent weatherability during the one-year outdoor weather resistance test and remarkable mechanical durability in sandpaper abrasion and sand impact tests. Therefore, the long-term self-cleaning DRC paint developed in this work has a potential application prospect in the field of building exterior wall or roof.