Regulatory mechanism of highly transparent, low-thermal-conductivity aerogel film for energy-efficient windows

Aerogels are a focus of research in energy-saving materials due to their unique nanoporous structure. However, achieving aerogels with simultaneously high transparency, low thermal conductivity, and remarkable mechanical robustness remains a challenge. Herein, a highly transparent, low thermal conductivity, and mechanically robust silica aerogel is fabricated through sol-gel process combined with supercritical drying. By systematically optimizing the concentrations of methyltrimethoxysilane, cetyltrimethylammonium bromide, urea, and acetic acid in solution, we obtained an aerogel film with transparency of 97.83 % in the visible spectrum, thermal conductivity of 0.0149 W·m<sup>-1</sup>·K<sup>-1</sup>, and maximum compressive strain of 27%. When applied as a sandwich material between double glass, it demonstrates significantly enhanced thermal insulation performance while maintaining transparency comparable to that of conventional glass. Furthermore, the silica aerogel film exhibits exceptional hydrophobicity due to the presence of methyl groups, which enhances its structural stability. Consequently, this high-performance silica aerogel film demonstrates strong potential for energy-saving windows, making it an ideal candidate for retrofitting existing buildings and integrating into emerging architectural glazing systems.