6. Conclusion

Aerogels have remarkable properties: very low density, high specific surface area, low refractive index and dielectric constant, low thermal conductivity and acoustic velocity... Structurally, aerogels are characterized by three physical components: the solid phase, the porous phase and the specific surface area separating the two phases. Under certain synthesis conditions, they can have a fractal structure between 1 and 100 nm.

The characteristics and relative influence of each of these components (chemical composition of the solid phase, pore volume and pore size distribution, chemical nature and accessibility of the interface) give aerogels particular and unique properties, leading to specific applications. In general, but not exclusively, these properties are linked to their very high porosity associated with the high tortuosity of the coherent solid network....