5 - Drying of Wet Gels

Summary

Aerogel technology provides lightweight materials with an outstanding combination of properties. One major problem for the preparation of aerogels is how to eliminate the liquid solvent from the wet gel while avoiding shrinkage, cracking and collapse of the gel structure. Several techniques have been used and are still under development. The chapter discusses three techniques to dry a wet gel: ambient or evaporative drying, freeze drying and supercritical drying. All aspects of each drying technique are explained in detail, andvarious effects of drying routines on the final aerogel structure and thus properties are discussed.