Aerogels are the lightest solid materials known to man, and they have an extremely low density. They are created by combining a polymer with a […]
Continue readingThe Chemical Formula of an Aerogel
Aerogels are the lightest solid materials known to man, and they have an extremely low density. They are created by combining a polymer with a solvent to form a gel, then removing the liquid and replacing it with air. These remarkable properties have made the development of aerogels one of the hottest areas of material science research, and they are poised to revolutionize building insulation.
The chemical formula of an aerogel is comprised of a silica network that is cross-linked with a polymer or other material such as a metal or carbon. The resulting material is highly porous and exhibits very low densities, which make them ideal for superinsulation applications. The unique nature of these materials has attracted a lot of interest from researchers around the world, but the lack of a simple synthetic procedure has limited their commercialization.
Several different methods have been used to synthesize aerogels. Most commonly, a polymer precursor such as TEOS is combined with a polymer-modified silane to produce a gel. The gel is then dried under ambient pressure. This process is usually slow, and it may take days for the reaction to complete. To speed up the reaction, acid or base catalysts can be added.
Other synthesis techniques include co-condensation of silane precursors and subsequent ambient pressure drying. MTMS can be co-condensed with monofunctional and bifunctional organosilanes such as VTMS, VDMMS, CPTMS, MAPTMS, and AMDMS to fabricate functional and hydrophobic aerogels with varying properties (reflectivity, oil adsorption, and compressive strength) [75]. Cok and Gizli prepared flexible hexylene-bridged silsesquioxanes by using the combination of TEOS and TMCS as the precursor. The addition of hexylene groups to the skeleton significantly enhanced the flexibility of the aerogels and allowed them to be compressed up to 70% without cracking or breaking [76].