Percolation of the organic phase in hybrid organic-inorganic aerogels

The properties (texture, mechanical behaviour, etc.) of hybrid organic-inorganic silica aerogels change dramatically when the concentration of the organic additive is varied from a given value. It has been known for several years that this critical concentration is around 40% of the total weight of silica present in the sample. We have made use of a new structural model to conclude that this concentration of 40% by weight corresponds to the percolation threshold of the organic phase.