Synthesis of hydrophobic silica aerogel and its composite using functional precursor

Hydrophobic silica aerogel (HSA) was synthesized by a facile sol–gel method and ambient pressure drying with methyltrimethoxysilane as precursor. The effect of precursor concentration on the sol–gel behavior, structure, and thermal conductivity of HSA was investigated. HSA with apparent density of 0.088 g/cm³ showed a thermal conductivity of 0.018 W/(m·K), a specific surface area of 502 m²/g and a pore volume of 1.66 cm³/g. The hydrophobic groups in HSA had a good thermal stability up to 450 °C. Polypropylene felt was used to synthesize hydrophobic silica aerogel composite (HSAC). The effect of sol loading on the structure and thermal conductivity of HSAC was investigated. HSAC with equivalent sol loading exhibited a low shrinkage of 2.5% and a low thermal conductivity of 0.020 W/(m·K). Finally, the preparation method of the HSA is facile and environmentally friendly, and the resulting composite is a promising candidate for thermal insulation under humid environments.