Mie-optimized PMMA particles for fully polymer-based radiative cooling coatings with high reflectance and hydrophobicity.

Passive radiative cooling materials achieve cooling without energy consumption by reflecting sunlight and emitting thermal radiation to the cold outer space (3 K). This study synthesizes poly(methyl methacrylate) (PMMA) particles with Mie scattering properties through emulsifier-free emulsion and dispersion polymerization to control particle size, enhancing their scattering and reflectivity. A high-emissivity polydimethylsiloxane (PDMS) matrix is used to fabricate a composite material, enabling complementary radiative effects between PMMA and PDMS within the atmospheric transparency window, thus enhancing the cooling efficiency.