Strengthening of Water Glass Based Aerogel by TEOS

In order to prevent the irreversible collapse of the silica aerogel backbone upon the drying of the liquid phase of silica wet gel derived from water glass based silicic acid, we tried to strengthen the aerogel back bone by aging silica wet gels in water and TEOS/ethanol solutions. Although aging of silica wet gels in water has been shown to grow the neck between silica particles of the aerogel backbone, it is hard to obtain a crack-free aerogel monolith. On the other hand, the mechanical stability of silica aerogels was improved significantly by aging the wet gel in TEOS/ethanol solutions with different TEOS content.