Scalable radiative cooling paints based on random porous polymers

Radiative cooling is an emerging strategy to achieve cooling without using electricity, where a surface has high solar reflectance and high thermal emittance simultaneously. Porous polymer paint is a scalable approach to realize radiative cooling. For instance, porous poly(vinylidene fluoride-co-hexafluoropropene) (P(VdF-HFP)) coatings exhibit near-perfect solar reflectance Rsolar (> 0.96) and long-wave infrared (LWIR) emittance εLWIR (~ 0.97) for radiative cooling. In this presentation, I will discuss the principle, manufacturing of such porous film. Methods to switch the optical/thermal properties from radiative cooling to solar absorption will also be discussed, which represents an “ice-house” to “green-house” transition useful for tuneable radiative cooling at night and potentially, thermal camouflaging. At the end, strategies to achieve colored radiative cooling will be discussed too