Super-stretchable yarn made from graphene

Researchers from the US and Japan have developed a simple method to make strong, stretchable graphene oxide yarn.
Researchers at Penn State in the US and Shinshu University in Japan have developed a simple, scalable method of making graphene oxide (GO) fibres that are strong, stretchable and can be easily scrolled into yarns.
The researchers made a thin film of graphene oxide by chemically exfoliating graphite into graphene flakes, which were then mixed with water and concentrated by centrifugation into a thick slurry.
The slurry was then spread by bar coating - something like a squeegee - across a large plate.

When the slurry dries, it becomes a large-area transparent film that can be carefully lifted off without tearing.
The film is then cut into narrow strips and wound on itself with an automatic fibre scroller, resulting in a fibre that can be knotted and stretched without fracturing.

"We found this graphene oxide fibre was very strong, much better than other carbon fibres. We believe that pockets of air inside the fibre keep it from being brittle," said Mauricio Terrones, professor of physics, chemistry and materials science and engineering at Penn State.
Terrones and colleagues believe this method opens up multiple possibilities for useful products. For instance, removing oxygen from the GO fibre results in a graphene fibre with high electrical conductivity.

Adding silver nanorods to the graphene film would increase the conductivity to the same as copper, which could make it a much lighter weight replacement for copper transmission lines.
Many kinds of highly sensitive sensors are also imaginable, researchers said.
"The importance is that we can do almost any material, and that could open up many avenues - it's a lightweight material with multifunctional properties," Terrones said.
The discovery was published in the journal ACS Nano.