Simulated and experimental evaluation of optical property of the polymeric radiative cooling coating with gradient-dispersed particles

Passive daytime radiative cooling has been widely acknowledged as a promising and environmental-friendly method to achieve considerable cooling capacity. Wherein, the polymeric radiative cooling coatings with dispersed particles are considered to be a superior candidate among various existing radiative cooling coatings. Up to now, to achieve better cooling performance, the theoretical and experimental exploration of the effect of the structural parameter, like the particle size, on the spectral optical properties of the polymeric radiative cooling coating with dispersed particles has been conducted. However, little attention has been paid to investigate the impact of the distribution pattern of the particles, like the gradient distribution. Herein, the reflectance of the radiative cooling coating under gradient distribution was numerically evaluated through the Lorenz-Mie theory which considers the effect of the absorptive medium and the multilayered Monte Carlo method. It is found that the solar reflectance and infrared emittance are relatively higher as the particle size increases or volumetric fraction declines along the direction of the incident irradiance. Meanwhile, the spectral reflectance in the absorptive wavelength range of the polymeric medium is primarily determined by the properties of the first layer the incident irradiance encounters, which is also confirmed by comparing the reflectance under overall monodispersed and even distribution. On this basis, a theoretically near-broadband/selective coating is proposed and demonstrated to realize the broadband and selective function at two sides. It is believed that our work brings a novel paradigm for the development and potential application of the polymeric coating with dispersed particles. © 2025 Elsevier Masson SAS