by Kathy Chambers on Fri, February 28, 2014
Aerogels are some of the most fascinating materials on the planet. They were discovered in the 1930s by Stanford University’s Samuel Kistler who proved that he could successfully replace a gel’s liquid with a gas by drying it, thereby creating a substance that was structurally a gel, but without liquid. Since their invention aerogels have primarily been made of silica but can be made of a growing variety of substances including transition metal oxides, organic polymers, biological polymers, semiconductor nanostructures, graphene, carbon, carbon nanotubes and metals as well as aerogel composite materials and the list is growing.
A brief glimpse of beautiful aerogels shows us they are in a class by themselves with combinations of materials properties that no other material possesses. And, these properties can be adjusted by tailoring the production process. Among other characteristics, aerogels are solid, rigid, and dry despite being named gels. They are the lightest known solids in existence and made of almost nothing. Silica aerogels, for example, typically consist of more than 96% air and the remaining 4% is a wispy web of silica. Their looks are also deceiving. You might think you could pass your hand right through a transparent silica aerogel, sometimes nicknamed ‘frozen smoke,’ but think again—it is very solid to the touch. Extraordinarily strong, aerogels are able to support over 2000 times their own weight. They are also very fragile-- at first cushiony to the touch, they shatter with a bit more pressure. They are good thermal insulators and are capable of withstanding temperatures in excess of 1000 degrees Fahrenheit. They can be mixed, formed, spread, sprayed or fabricated into slabs, pellets, or most any shape desirable. Because aerogels have these incredible characteristics, they are outstanding materials for insulation and building manufacturing, coatings, space missions, vehicles, filters, appliances, and drug delivery systems.
There is a growing market for aerogels in consumer applications. I’ve seen aerogels used in superinsulating blankets, as thermal protection for divers, in foot insulation for extreme environments, as insulation for buildings, pipelines, and shipping containers. I’ve seen aerogel bottled and displayed as art. I’ve even seen pink heart-shaped aerogels for your valentine. The list goes on. Aerogels are indeed intriguing, beautiful, and useful, but the amazing advancements being made with these aerogel materials by researchers at DOE and NASA laboratories, along with their industry partners, are truly exciting.
Dr. William Watson, Physicist, of OSTI’s staff provides a layman’s overview of today’s aerogel research and production techniques and potential common and special uses of the most recent aerogel materials in his latest white paper In the OSTI Collections – Aerogels. He also provides an extensive list of DOE research sources and organizations for reference. Additional aerogel research papers and related resources can be found in DOE’s Scitech Connect and in Science.gov and WorldWideScience.org.