Researchers at Columbia Engineering have invented a high-performance exterior PDRC [passive daytime radiative cooling] polymer coating with nano-to-microscale air voids that acts as a spontaneous air cooler and can be fabricated, dyed, and applied like paint on rooftops, buildings, water tanks, vehicles, even spacecraft -- anything that can be painted. They used a solution-based phase-inversion technique that gives the polymer a porous foam-like structure. The air voids in the porous polymer scatter and reflect sunlight, due to the difference in the refractive index between the air voids and the surrounding polymer. The polymer turns white and thus avoids solar heating, while its intrinsic emittance causes it to efficiently lose heat to the sky.
Journal Reference:
J. Mandal, Y. Fu, A. Overvig, M. Jia, K. Sun, N. Shi, H. Zhou, X. Xiao, N. Yu, Y. Yang. Hierarchically porous polymer coatings for highly efficient passive daytime radiative cooling. Science, 2018; eaat9513 DOI: 10.1126/science.aat9513
The new desert home paint?
(Score: 2, Informative) by Anonymous Coward on Friday September 28 2018, @05:52PM (2 children)
I lived in the Arizona desert for close to two decades. As a teenager a door-to-door sales guy sold us a polymer insulated roof coating for our mobile home as well as a microfiber sunscreen for our windows. It did indeed help keep things cooler indoors. So I'm having a hard time understanding what is truly novel here.
(Score: 2) by bob_super on Friday September 28 2018, @06:57PM (1 child)
Read again: This (and the previous one I linked) not only reflect most incoming light, they also radiate heat in the infrared faster than you'd expect. In the end, the small incoming heat is less than the outgoing heat, so the result is a coated object which stays at ambient despite being in the sun.
(Score: 0) by Anonymous Coward on Saturday September 29 2018, @05:03AM
It actually cools by 6 C from ambient.