Scalable Aqueous Processing‐Based Passive Daytime Radiative Cooling Coatings

By Wenlong Huang, Yijun Chen, Yubing Luo, Jyotirmoy Mandal, Wenxi Li, Meijie Chen, Cheng-Chia Tsai, Zhongqiang Shan, N. Yu, Yuan Yang. Advanced Functional Materials, 2021

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Passive daytime radiative cooling (PDRC) can realize electricity‐free cooling by reflecting sunlight and emitting heat to the cold space. Current PDRC designs often involve costly vacuum processing or a large quantity of harmful organic solvents. Aqueous and paint‐like processing is cost‐effective and environmentally benign, thereby highly attractive for green manufacturing of PDRC coatings. However, common polymers explored in PDRC are difficult to disperse in water, let alone forming porous structures for efficient cooling. Here, a simple “bottom‐up” ball milling approach to create uniform microassembly of poly(vinylidene fluoride‐co‐hexafluoropropene) nanoparticles is reported. The micro‐ and nanopores among secondary particles and primary particles substantially enhance light scattering and results in excellent PDRC performance. A high solar reflectance of 0.94 and high emittance of 0.97 are achieved, making the coating 3.3 and 1.7 °C cooler than commercial white paints and the ambient temperature, under a high solar flux of ≈1100 W m−2. More importantly, the volatile organic compound content in the aqueous paint is only 71 g L−1. This satisfies the general regulatory requirements, which are critical to sustainability and practical applications.

Subfields: Atomic and Molecular Physics, and Optics, Civil and Structural Engineering, Environmental Engineering

View Paper: https://www.semanticscholar.org/paper/303f5c18b90a346abe81272b7445d3319dc86fc8