23 October 2011


It is known as "frozen smoke", "solid smoke", "solid air" and even "blue smoke" due to its translucency. Aerogel is a material with the lowest bulk density of any known porous solid. It is light and contrary to popular belief, it breaks easily when pressed firmly enough. It is strong structurally but like glass, it will shatter when deliberate force is applied to it.
Despite their name, aerogels are rigid, dry materials and do not resemble a gel in their physical properties; the name comes from the fact that they are derived from gels. Pressing softly on an aerogel typically does not leave a mark; pressing more firmly will leave a permanent depression. Pressing firmly enough will cause a catastrophic breakdown in the sparse structure, causing it to shatter like glass—a property known as friability; although more modern variations do not suffer from this. Despite the fact that it is prone to shattering, it is very strong structurally. Its impressive load bearing abilities are due to the dendritic microstructure, in which spherical particles of average size 2–5 nm are fused together into clusters.
Source: Wikipedia

If you have time, check this video about Aerogels by the University of California. This material has chemists, physicists, astronomers, and materials scientists utilizing its properties in a myriad of applications (ff to 3:49 to skip the introduction):

Aerogels are created by removing the liquid from gels. In 1931, Samuel Stephens Kistler discovered this material over a bet whether or not liquid can be replaced with gas on jellies without causing shrinkage. This is achieved by extracting the liquid component through supercritical drying. Although the first and popular aerogels were produced from silica gels, other elements can be used such as aluminum, chromium, tin oxide and carbon.

The main problem with other elements is that they may cause toxic reactions to people handling them. Even if silicon based aerogels are safe, it can still be an irritant to the eyes, skin, respiratory tract, and digestive system. It is recommended that protective handling gear such as goggles and gloves be worn whenever handling aerogels.

Students and researchers at Union college patented a process that can produce aerogels at a fraction of a time that the usual process take. Instead of using an autoclave to extract the liquid, the students used a hot press.

Much of their research is also conducted on the characterization of aerogels. Past projects have focused on their density, surface area, morphology and photolytic qualities.

Since over 90% of the material is made up of air, it is a very good insulator and is its most popular use. As stated in wikipedia, the first residential use of aerogel as an insulator is in the Georgia Institute of Technology's Solar Decathlon House where it is used as an insulator in the semi-transparent roof. Commercial companies have now introduced aerogel infused materials for building structures.

Aside from that, NASA uses the material to trap space dust particles aboard the Stardust spacecraft. Even clothing manufacturers have used aerogel in its products. Shiver Shield, a brand of cold weather garments that is insulated with encapsulated aerogel, was recently introduced to the market in 2011.

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