Preparation and surface modification of SiO₂ aerogel by ambient pressure drying

SiO₂ aerogel was prepared by using waterglass as the Si source, formamide as the catalyst and glycol as the drying chemical controlling additive (DCCA) via sol-gel method and ambient pressure drying. It is revealed that a certain amount of excessive formamide is favorable for preparation of the aerogel with high porosity, while more excessive glycol can deteriorate the formation of nano-porous SiO₂ aerogel network. Additionally, the pH value of the reaction system has a strong impact on the microstructure and properties of prepared SiO₂ aerogel. The aerogel modified with dimethyldiethoxysilane (DMDEOS) shows an excellent hydrophobic feature. The structure and properties of hydrophobic silica aerogel were analyzed by Fourier transform infrared spectra (FTIR), thermogravimetric (TG) and Differential Scanning Calorimetry (DSC).