Technology & Science

World's lightest material weighs 75 times less than Styrofoam

A group of German scientists say they have created a porous carbon material that is four times lighter than the lightest man-made material to date.

German scientists create carbon-based material that weighs 0.2 milligrams per cubic centimetre

A water droplet sits atop a piece of Aerographite, an ultralight carbon-based material that is water repellant and electrically conductive. (Christian-Albrechts University of Kiel)

A group of German scientists say they have created a porous carbon material that is 75 times lighter than Styrofoam and four times lighter than the lightest man-made material to date.

Researchers at the Technical University of Hamburg-Harburg (TUHH) and Christian-Albrechts University of Kiel call the new material Aerographite. They describe it as a jet black, non-transparent carbon-made material that is flexible, water repellent, stable and a good conductor of electricity.

Aerographite in action

Watch Aerographite being compressed.

See Aerographite dance.

At a micro level, it resembles a network of porous carbon tubes, the scientists said in a press release.

"Think of the Aerographite as an ivy web, which winds itself around a tree, and then take away the tree," said Rainer Adelung, a materials science professor at Kiel and co-author of a paper on the material that appeared in the journal Advanced Materials earlier this month. 

At 0.2 milligrams per cubic centimetre, Aerographite is lighter and less dense than the former record holder, a nickel-based material that weighs 0.9 milligrams per cubic centimetre. This is in part because carbon has a lower atomic mass than nickel.

The lattice-like nickel material, created by researchers at HRL Laboratories, the California Institute of Technology and the University of California at Irvine, was described in a November 2011 article in the journal Science.

Can be compressed without damage

An electron microscope image of the fine mesh that makes up the carbon tubes at the heart of the new material. (Technical University of Hamburg-Harburg )

To create Aerographite, Adelung and his colleagues first heated zinc oxide powder up to 900 degrees C to turn it into a crystalline form. They then coated the zinc oxide particles with graphite that was only several atomic layers thick.

Once hydrogen was introduced into the process, it reacted with the oxygen in the zinc oxide, producing steam and zinc gas and leaving behind an interwoven, tube-like carbon structure.

"The faster we get the zinc out, the more porous the tube's walls get, and the lighter is the material," said Matthias Mecklenburg, a PhD student at TUHH and a co-author of the paper, in the release.

The researchers say the material is unique in that, unlike other ultra-lightweight materials, it can withstand both tension and compression. It can be compressed up to 95 per cent and return to its original form without damage, Adelung said.

"Up to a certain point, the Aerographite will become even more solid and therefore stronger than before," he said.

Applications could include batteries, static reducers

Aerographite in the making. Crystallized zinc oxide, in white, turns into steam and zinc gas when hydrogen is added, leaving behind a mesh of carbon tubes. (Technical University of Hamburg-Harburg )

Adelung and his colleagues said the material has many possible applications. It could help make lithium batteries lighter by reducing the amount of electrolyte solution needed to conduct electricity inside the battery. Such lightweight batteries could be especially useful in electric cars or bikes, the researchers said.

Aerographite could also help reduce the static that results when friction, heat or pressure is applied to plastic by making plastic a better conductor of electricity.

It could also come in handy as a water purifier, since its ability to oxidize could be used to remove pollutants.