How are aerogels produced today?
They can be produced by the sol-gel polymerization of selected silica or resorcinol-formaldehyde (RF) monomers in solution. This solution is cast into the desired shape and forms into a highly crosslinked gel. The solvent is then removed from the pores of the gel. The remaining rigid monolithic shape consists of covalently bonded, nanometer-sized particles that are arranged in a three-dimensional network. RF aerogels are carbonized to form pure carbon aerogels or can be applied to carbon paper to form sheets of RF aerogels that can be carbonized. Carbon aerogels are produced by the sol-gel polymerization of selected organic monomers in solution. After the solvent is removed, the resultant organic aerogel is pyrolyzed in an inert atmosphere to form a carbon aerogel.
