Hydrophobic Silica Aerogel with Higher Flame Retardancy, Thermal Radiation Shielding, and High-Temperature Insulation Properties Through Introduction of TiO2

Abstract

SiO2 aerogels have garnered significant attention for thermal insulation applications due to their exceptional hydrophobicity and thermal resistance. However, the organic functional groups enabling hydrophobicity introduce flammability concerns, limiting their safe implementation in high-temperature environments. This study presents a novel TiO2 doping strategy (SA/TiO2) that simultaneously enhances thermal safety while preserving the material’s intrinsic advantages. The optimized SA/TiO2 composite demonstrates remarkable fire resistance, achieving a 44% reduction in gross calorific value (GCV) and a 25.4% decrease in total heat release (THR) compared to conventional aerogels. Thermogravimetric analysis reveals substantial thermal stability improvements, with TiO2 incorporation elevating the initial and peak decomposition temperatures by 207 °C and 167 °C, respectively. When integrated into fiber-reinforced SiO2 aerogel composites, the 10% TiO2-doped formulation achieves an ultra-low GCV of 2.75 MJ/kg while maintaining superior insulation performance (~18 mW/m·K). Notably, the composite demonstrates exceptional high-temperature stability, retaining minimal thermal conductivity of 25.5 mW/m·K at 600 °C. The titanium dioxide phase effectively attenuates thermal radiation transmission while preserving the matrix’s nanoporous architecture, thereby synergistically enhancing both fire safety and thermal insulation capabilities in demanding operational environments.