4. Conclusion

The history of sol-gel materials is punctuated by numerous discoveries, yet very few of them have led to industrialization. The cost of raw materials, the reproducibility of the synthesis method and the drying process, which must be adapted to each formulation, have been the main obstacles. However, as the reader has seen in the case of aerogels, the discovery of a new, inexpensive source of Si, enabling a significant reduction in production costs, and the advent of new requirements in terms of thermal and acoustic insulation, have all contributed to an explosion in the aerogel market. In a completely different field, the start-up Ethera has led the way by demonstrating that it is possible to produce monolithic xerogels of good optical quality for the optical detection of atmospheric pollutants present at very low levels. Other applications will soon follow, as the potential of these materials...