Title:One‐Component Stereoscopic Oligosiloxane–Based Polyurea Radiative Cooling Coatings

Abstract:Passive daytime radiative cooling (PDRC) technology is an emerging and promising zero‐carbon solution. However, existing PDRC materials usually exhibit poor mechanical properties and lack self‐cleaning ability, which can reduce the lifespan of the coating and affect its cooling effect. To address these challenges, a one‐component stereoscopic oligosiloxane–based polyurea radiative cooling coating is developed. The coating is fabricated by integrating blocked amine–oligosiloxane nanoclusters, isocyanate‐terminated curing agents, and inorganic aluminum oxide (Al₂O₃) particles. The unique stereoscopic oligosiloxane structure, characterized by high functionality and self‐reinforcing effect, endows the polyurea with a highly cross‐linked organic–inorganic hybrid network structure. This structure provides exceptional hardness and modulus for the coating, with a surface hardness of ≈227 Mpa and a modulus of ≈9.7 Gpa. In addition, the high infrared emissivity of Si─O─Si bonds and the high reflectivity of Al₂O₃ enable the coating to have an excellent cooling effect of ≈9 °C below ambient temperature during the daytime. The coating also exhibits excellent versatility. The introduction of polydimethylsiloxane (PDMS) endows the coating with excellent self‐cleaning and antifouling properties. Furthermore, spraying fluorinated nanosilica (F─SiO₂) on the surface enables superhydrophobicity and water droplet power generation. The novel PDRC coating provides a sustainable solution for cooling buildings.

DOI: 10.1002/smll.202504187