Mechanically resilient, hybrid silicone aerogel for thermal insulation, daytime radiative cooling and sustained flame protection

Aerogels are ideal materials for thermal insulation and protection. However, ceramic and carbon aerogels are generally brittle, whereas polymer aerogels often collapse and lose insulation capability under flame exposure, compromising effective thermal management across both daily use and fire emergencies. We construct a hybrid silicone aerogel with continuous silicone matrix reinforced by a silica network, enabling low thermal conductivity, excellent mechanical resilience and a unique flame-induced nano-hollowing ceramization process. Under flame, the nano-hollowing process yields an efficient thermal barrier with an unexpected decrease in thermal conductivity, enabling a 10-mm-thin panel to maintain its back-side temperature below 120 °C for at least 25 min. In addition, the aerogel provides daytime radiative cooling of 7.7 °C under midday solar irradiation. With such multifunctionality and fabrication scalability, our silicone aerogel is desirable for many strategic areas such as energy-efficient buildings and electric vehicles, where effective thermal management and sustained flame protection are greatly demanded. Aerogels provide excellent insulation, but conventional aerogels exhibit deterioration in insulation under flames, limiting sustained protection. Here the authors construct resilient hybrid silicone aerogels with low thermal conductivity and sustained flame protection enabled by in-situ nano-hollowing.