A simple facile preparation of methyltriethoxysilane based flexible silica aerogel monoliths

A novel inexpensive and green method was developed to rapidly prepare methyltriethoxysilane (MTES) based flexible silica aerogel monoliths via ambient pressure drying. By controlling the amounts of MTES, ethanol and water without the conventional complex steps of surface modification and solvent exchange, the silica aerogel monoliths with excellent integrity, flexibility and compressibility were obtained. Benefiting from the appropriate numbers of methyl groups contained in MTES, this method could well maintain the monolithic structure when dried at an atmospheric pressure. The density of 0.10 g/cm3 with the porosity of 95.5% and the thermal conductivity as low as 0.038 W/(mK) could be achieved. The total unrecoverable strain loss was 10% after 20-cycle continuous compression upon 50%-strain loading.