Enhanced weathering resistance of sandstone cultural relics using a composite coating of F-modified TiO2 nanoplates and SiO2 nanoparticles

Water-induced deterioration poses a significant threat to sandstone cultural heritage, necessitating effective protective measures. This research investigates a fluorine dual-modified nanocomposite coating composed of nanoplate-like TiO 2 and nanoparticle SiO 2 , utilizing 1H, 1H, 2H, 2H-perfluorodecyl triethoxysilane as the modifier. The study aims to optimize the modifier concentration for enhanced hydrophobicity , while also assessing the coating’s penetration depth and its effect on sandstone breathability. An optimal formulation, consisting of a TiO 2 -to-SiO 2 mass ratio of 75:25 combined with 80 µL of the perfluorodecyl triethoxysilane modifier, yielded exceptional water and oil contact angles of 150.1° and 139.3°, respectively. Even after 210 h of UV exposure, the coating exhibited remarkable stability, with only a minor decrease in contact angles. Furthermore, the treatment effectively preserved the air permeability of the sandstone. This F-modified nanoplate TiO 2 /nanoparticle SiO 2 composite coating demonstrates significant potential for the long-term protection of sandstone cultural relics against environmental weathering, offering a balance of high hydrophobicity and breathability.