A new low-density aerogel has been created by researchers at the University of Pennsylvania. It's made of carbon nanotubes and exhibits extraordinary characteristics, being able to sustain a mass 8,000 times bigger than its own.

Aerogels are low-density gel-like solids, where the liquid component of the gel has been replaced with gas. Consequently, they become remarkable materials, semi-transparent, ultra-light and very good heat insulators.

Usually, they are made of 90-99.8% air, with densities ranging from 1.9 to around 150 mg/cm³ and constructed from silicon dioxide or other organic polymers. They are mostly used in radiation detectors and thermal insulators.

Arjun G. Yodh and Jay Kikkawa of the department of Physics and Astronomy at Penn University have worked together with a team of researchers on a new aerogel made of carbon nanotubes which they created by freeze-drying or critical-point-drying CNT networks suspended in fluid.

The result was a carbon nanotube network with easily controllable carbon concentration, electrical conductivity and strength. The team was able to demonstrate reproducible conductivity and to maintain control of the density, microscopic structure and shape of the CNT aerogels, though usually such carbon nanotube composites are very fragile.

The added strength was produced by introducing polyvinyl alcohol to create a more even dispersion of CNT throughout the aerogel.

There are many applications of the aerogels and even NASA used aerogel to trap space dust particles aboard the Stardust spacecraft. The particles vaporize on impact with solids and pass through gases, but can be trapped in aerogels. NASA also used aerogel for thermal insulation of the Mars Rover and space suits.

New carbon nanotube aerogels are the most advanced so far and may even lead to future applications in chemical or biological sensors and they could also be used as drug delivery system due to their biocompatibility.