Superhydrophobic and Abrasion-Resistant Coatings for Above-Ambient Passive Daytime Radiative Cooling via the Scalable Spraying Process
Hongzhi Pan, Chengjie Qu, Bo Wang, Qingqing Lu, Hailong Zhang, Xingxiang Ji, Ligang Gai, Zuankai Wang, Libin Liu
Abstract
Passive daytime radiative cooling (PDRC) offers an energy-free cooling strategy by reflecting solar radiation and emitting thermal radiation through an atmospheric window. However, existing PDRC materials face challenges, such as contamination, mechanical damage, and durability issues. Herein, a superhydrophobic and abrasion-resistant PDRC coating is developed using a fluorinated acrylic polymer matrix with SiO 2 and TiO 2 nanoparticles, fabricated via a simple one-step spraying process. By regulating the content of different components, the optimal coating achieves high solar reflectivity (91.1%) and atmospheric window emissivity (93.7%) and has a superhydrophobicity of 157°, preventing dust and water adhesion. The coating maintains excellent durability and optical performance after 3000 abrasion cycles under a 250 g load. The coating can also be processed into colored variants without compromising its high reflectivity and emissivity. Moreover, it demonstrates excellent above-ambient cooling performance at daytime and achieves a temperature reduction of 1.8 °C at daytime and 1.7 °C at nighttime compared with the commercial coating. These results highlight a scalable and cost-effective solution for sustainable cooling applications.