Publication

Abstract : Aerogels are a special class of open porous materials derived from sol–gel transformation. Gel drying is accomplished accompanied by zero or very low gel shrinking. They consist of interconnected particles that essentially comprise meso- and micropores. Aerogels as a class are made up of various chemically different constituents, namely, ceramic, carbon, polymer, organo-inorganic, and metal, of which more popular are silica and carbon aerogels. Because of their unique porosity characteristics combined with extremely low densities, they find use in several novel applications, such as extremely low thermally conductive thermal insulation, dielectric shielding, energy storage, water purification, petroleum oil spill removal, etc. Drying with extremely low shrinkages, demand special drying techniques, such as supercritical drying, ambient pressure drying, freeze drying, etc. In this chapter, the discussion is limited to the silica version of the aerogel. Topics such as aerogel history, sol–gel chemistry, earlier attempts at aerogel synthesis, drying techniques, and a few applications are covered.