Hydrophobic silica wet gel and aerogel

A method of making a hydrophobic silica aerogel having a density of between 100 mg/cc and 200 mg/cc, comprising the steps of:

• preparing a first solution by mixing tetramethoxysilane and solvent;
• preparing a second solution by mixing ammonium hydroxide and water;
• mixing the first solution and the second solution together to form a mixed solution;
• allowing components in the mixed solution to react to form silica wet gel;
• preparing a third solution by mixing ammonium hydroxide and solvent;
• preparing a fourth solution by mixing methyltrimethoxysilane and diluent;
• preparing a solvent exchange solution by mixing the third solution, the fourth solution and solvent;
• subjecting the silica wet gel to the solvent exchange solution to form a hydrophobic silica wet gel;
• and
• drying the hydrophobic silica wet gel to form hydrophobic silica aerogel;
• wherein the tetramethoxysilane and methyltrimethoxysilane are provided in a controlled amount selected to provide a molar ratio of tetramethoxysilane:methyltrimethoxysilane of greater than or equal to 3.86:1 and less than or equal to 6.11:1.