Aerogels: The lightest stuff on Earth gets lighter

Chemists from University of Central Florida make "frozen smoke" that is ultra-sensitive to detecting chemicals and changes in pressure.

Known as "the lightest material on the planet," aerogels consist mostly of air. But the services this stuff could potentially provide are substantial.

Their low thermal and acoustic conductivity makes them superb heat and noise insulators . They're very absorbent, perfect for an oil spill or umm, kitty litter . And depending on their construction, they can specifically filter certain toxins or pollution particles.

Unfortunately, their construction doesn't come easy, especially when made out of carbon nanotubes (silica, metal oxides, or other carbon-based materials typically comprise aerogels). But a team of scientists is reporting they've fabricated a multi-walled carbon nanotube (MWCNT) aerogel. Published in ACS Nano, the study describes this new "frozen smoke" as the lightest of its kind, with a density of just four milligrams per cubic centimeter.

The chemists, from University of Central Florida, removed the moisture from a wet gel of dispersed carbon nanotubes, leaving a material with honeycomb structures of varying degrees of porosity. The image below shows the pristine multi-walled carbon nanotubes at each step of the fabrication process.

The MWCNT aerogel has a large surface area and conducts electricity very well but not heat, so its use in electronics is far-reaching. After testing the aerogel's compressibility, the chemists also discovered it is highly squishable (video) and recovers quickly. According to the study, this sensitivity to pressure and its porosity make the material a good candidate for sensing chemical vapors and changes in pressure. So if you are one who tends to think heft connotes value, you may be wrong in the case of areogels.

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Images: NASA and University of Central Florida

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