Comparative studies on the physicochemical properties of in-situ hydrophobic silica aerogels by ambient pressure drying method

Hydrophobic SiO₂ aerogels show great promise for diverse smart applications due to their superhydrophobic surfaces combined with low thermal conductivity property. Hydrophobic tetraethoxysilane (TEOS)/methyltrimethoxysilane (MTMS) (TM) and TEOS/methyltriethoxysilane (MTES) (TE) gels were prepared by in-situ technique, and dried by ambient pressure drying (APD). The evolution of microstructure and chemical-physical properties of the TM and TE aerogels treated by different temperatures were investigated. Under the ultra-low and high temperature treatment, the TM and TE aerogels showed the low thermal conductivity (0.020 ~ 0.031 W m^{− 1} K^{− 1}), high specific surface area (410.85 ~ 830.10 m² g^{− 1}) and good hydrophobicity with the water contact value from 124.2 ~ 155.7°. This work provided an effective method to prepare hydrophobic SiO₂ aerogels with excellent ultra-low, high temperature resistant using double silicon sources as co-precursors, which could be an appropriate candidate for thermal insulation, catalysis and environmental protection.