Aerogel – The World’s most amazing substance.
It looks like frozen smoke. And it’s the lightest solid material on the planet. Aerogel insulates space suits, makes tennis rackets stronger and could be used one day to clean up oil spills. Lawrence Livermore National Laboratory scientist Alex Gash shows us some remarkable properties of this truly unique substance.
Aerogels are the world’s lightest solid materials, composed of up to 99.98% air by volume. Aerogels are a diverse class of amazing materials with properties unlike anything else. Transparent superinsulating silica aerogels exhibit the lowest thermal conductivity of any solid known.
Ultrahigh surface area carbon aerogels power today’s fast-charging supercapacitors. And ultrastrong, bendable x-aerogels are the lowest-density structural materials ever developed.
Origins of Aerogel
As a material created on a bet between two scientists in the late 1920s, may be the most unique substance on Earth. It’s the lightest solid in existence — Guinness World Records even said so — but it can support 500 to 4,000 times its own weight (depending upon whom you ask)
A cubic inch of aerogel could be spread out to cover an entire football field. It’s breathable and fireproof, and it absorbs both oil andwater. Aerogel is also amazingly strong, considering its weight.
Aerogels can be great electrical conductors, yet when made from different materials, they are also one of the best insulators ever known.
This amazing video shows Aerogel protecting chocolate from a BLOWTORCH! AWESOME!
The Creation of Aerogel
Aerogel begins as a gel, called alcogel. Alcogel is a silica gel with alcohol inside its pores. Simply evaporating the alcohol out of the silica structure would cause the structure to contract, much like a wet sponge will deform when left on a counter to dry. Instead of relying just on evaporation, the gel has to besupercritically dried. Here’s what it takes:
- Pressurize and heat the gel past its critical point — the point at which there’s no difference between gas and liquid.
- Depressurize the gel while it still remains above its critical temperature. As the pressure decreases, molecules are released as a gas and the fluid grows less dense.
- Remove the gel from your heat source. After the structure cools, there’s too little alcohol to recondense back into liquid, so it reverts to a gas.
- Check out your final product. What’s left behind is a solid made of silica, but now filled with gas (air) where there was once liquid.
Supercritical drying is how the liquid “alco” part of the alcogel turns into a gas within the silica’s nanopores without the structure collapsing. The alcogel with its alcohol removed is now called aerogel, as the alcohol has been replaced by air. With only 50 to 99 percent of the original material’s volume, aerogel is a light, flexible and useful material [source: Steiner, Zero Gravity].