Aerogels are solid colloidal or polymeric networks that are generally ultra-light weight with open porosities. Aerogels are prepared by the drying of the wet gels in which the liquid inside the pores of the network of the wet gel is replaced by air. Aerogels are highly porous (∼99.8% porosity), low thermal conductivity, extremely low density, low dielectric constant, as well as low refractive index. Since the development and commercialization of silica aerogel-based blankets for thermal insulation, the number of studies that are being conducted at many laboratories around the world on using aerogels for applications other than insulation is growing at an accelerating pace. Aerogels can be organic or inorganic. Carbon aerogels is another class of aerogels obtained by pyrolysis of organic aerogels. Combining powerful sol-gel chemistry with different preparation techniques, such as supercritical deposition and Freeze casting has led to the development of aerogel supported nanoparticles with superior catalytic properties for any targeted reaction. These surprising features of aerogels are responsible for a wide range of technological applications. It acts as a good thermal and acoustic insulator due to its highly porous and lightweight structure. Due to its ultra-porous structure, it may be used as thermal insulation for spacesuits and vehicles. Silica aerogel is the most common aerogel, the same material as glass.
