PARIS - Engineers in the United States say they have devised a wafer-thin carbon paper that outperforms even a nanotube rival for strength, flexibility and lightness.
The substance, graphene oxide paper, is described on Thursday in Nature, the British journal, by scientists led by Rodney Ruoff of Northwestern University, Chicago.
It is derived from graphite, oxidised to form graphite oxide, which is then filtered and formed into neatly-structured layers, each a mere micron, or a millionth of a metre (0.0000393701 inches), thick.
The researchers have made small sheets of the dark-brown "paper" with thicknesses ranging from one to 100 microns, and tested it successfully for stress and tensile resilience against hi-tech competitors, including so-called bucky paper, which is made of carbon nanotubes.
Graphene oxide paper owes its exceptional physical qualities to a unique interlocking-tile lattice at atomic scale.
It also has intriguing electrical qualities, for the oxidisation process turns the material from a conductor into an insulator.
"In the future, it will be possible to tune the material as a conductor, semiconductor or insulator," Ruoff says. "One will be able to control the electrical properties without sacrificing exceptional mechanical properties."
The foil-like paper has many potential outlets, either alone or as a composite with plastics, ceramics or metals where flexible reinforcement is needed, such as in aircraft, cars and buildings.
It could also be used in batteries and supercapacitors, while its unique lattice structure could be electrically charged to make membranes with controllable permeability.
So far, only experimental sheets of the paper have been made, each of them around 12 centimetres (five inches) in diameter, but Ruoff believes that it would be quite easy to scale up to large sheets, helped by the fact that graphite is cheap and plentiful.
Ruoff's team are also pioneers in a new class of material called graphene, a sheet of carbon only one atom thick.
"The mechanical, thermal, optical and electrical properties of graphene are exceptional," says Ruoff.
In theory, graphene sheets could be superior to all other materials, "with the possible exception of diamond," he believes.
07/25/2007 17:01 GMT