Cork helps give 3D graphene structures elasticity
Graphene, the ultra-thin and highly electrically conductive material, is at the forefront of much modern-day research. The ancient, natural material, cork, has now opened new doors for its application.
By breaking down graphite into layers that are just one atom thick, the strong, chemically stable graphene is formed. It’s relatively robust, light structure, coupled with the fact that it conducts electricity excellently, means it is set to be employed in all manner of electrical and biomedical applications.
Scientists at Australia’s Monash University have managed to amplify the potential applications of graphene by mirroring cork’s structure. Graphene is usually formed in very thin layers, but by mimicking the structure of cork the team managed to form the material into 3-dimensional blocks.
Professor Dan Li, who led the research, states that previous research had focussed on exploiting the intrinsic properties of graphene, rather than engineering it into useable 3-dimensional structures. Previous attempts to assemble structures from the material had tended to result in brittle conformations with sub-par performance.
Professor Li states: "It was generally thought to be highly unlikely that graphene could be engineered into a form that was elastic, which means it recovers well from stress or pressure."
Cork is a material that is both lightweight and strong, so its structure was taken as a natural template on which to base larger graphene formations. "The fibres in cork cell walls are closely packed to maximise strength and individual cells connect in a honeycomb structure, which makes the material very elastic," said Ling Qiu, a PhD student at Monash.
A method called freeze casting allowed the researchers to form chemically modified graphene into a cork-like, 3-dimensional structure. The result was graphene blocks, not only lighter than air, but also capable of supporting 50,000 times their own weight, as well as being highly elastic and good conductors of electricity. The blocks’ elasticity was such that they were able to recover from more than 80% deformation.
"We've been able to effectively preserve the extraordinary qualities of graphene in an elastic 3-dimensional form, which paves the way for investigations of new uses of graphene - from aerospace to tissue engineering," said Professor Li.