Graphene QUILT: A good trampoline for elephants in stiletto heels
Wonder stuff's real-world weakness not for real - boffins
Fears that the radical wonder material graphene might not actually be strong enough for elephants to stand supported in mid-air on a thin film of it, on one leg, while wearing stiletto heels, have been disproven.
And the material - set to revolutionise just about everything, as soon as people can figure out ways to start using it - retains its amazing strength even if it contains manufacturing defects, a new study has suggested.
"We're excited to say that graphene is back and stronger than ever," enthuses James Hone, engineering professor, who's been looking into the matter.
As any fule kno, graphene is a flat molecular lattice arrangement of carbon atoms. It has various nifty properties, not least of them tremendous strength - so much that Hone once observed previously:
"It would take an elephant, balanced on a pencil, to break through a sheet of graphene the thickness of Saran Wrap."
However that sheet of carbon clingfilm would need, it had been thought, to be single molecules from side to side. Nobody can produce such vast, defect-free elephant-proof planar crystals of monomolecular graphene at the moment: rather, any large graphene sheet is more like a patchwork quilt of smaller pieces, joined together at the edges by erratic stitches of carbon-carbon bonds which are potentially much less strong than those holding the patches themselves together.
In research to date involving large graphene quilts, this stitching had seemed to be much less robust than had been hoped: so casting much doubt over the enticing prospect of paper-thin trampolines for elephants wearing spike heels - among many other brilliant graphene-based plans.
But now Hone and his colleagues, having looked into the matter, say that the problem lies in the methods used so far to make the graphene quilt. This is done by using chemical vapour deposition to grow graphene crystals on a copper backing in a high-temperature furnace. The copper is then got rid of using chemicals: and according to Hone, the chemicals mostly used thus far needlessly weaken the quilt's stitching.
If this is avoided, according to Hone and his crew, a large graphene quilt is no less than 90 per cent as strong as a single crystal of the stuff: in fact, graphene is indeed back as the wonder-material of the future. The researchers present their work in blockbusting boffinry mag Science, here.
"This is an exciting result for the future of graphene, because it provides experimental evidence that the exceptional strength it possesses at the atomic scale can persist all the way up to samples inches or more in size," says Professor Hone. "This strength will be invaluable as scientists continue to develop new flexible electronics and ultrastrong composite materials." ®
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