"Hone compares his test to stretching a piece of plastic wrap over the top of a coffee cup, and measuring the force that it takes to puncture it with a pencil. If he could get a large enough piece of the material to lay over the top of a coffee cup, he says, graphene would be strong enough to support the weight of a car balanced atop the pencil." - Sanjeev Singh

beautiful! i wonder is it going to take as long for graphene to become a consumer technology as it is taking for, say, fuel cells - Kirill Bolgarov

i question the part about supporting a car-pencil with a macro scale piece of the material - he sort of steps around it by claiming you could never make a perfect piece that large but i think that even if you could, its unlikely it would really have that strength - even if you assume you could nicely support the sheet on the edges, i think the actual number of covalent bonds surrounding the circumference of the pencil tip is far too small to support that force, given the typical strength of a covalent bond - bob

in this one, it says a sheet as thick as the plastic wrap, which is much much thicker/different: http://physicsworld.com/cws... "To put things in perspective: if a sheet of cling film (which typically has a thickness of around 100 µm) were to have the same strength as pristine graphene, it would require a force of over 20,000 N to puncture it with a pencil," he explained. "That is the force exerted by a mass of 2000 kg, or a large car!" - bob

Can someone please get some of this stuff into some bicycle tire tubes asap? Thanks. - Christopher Sacca

robbie, I think it depends how tautly the stuff is wrapped over the coffee cup. I'm imagining it's like a mesh with springs, if I push in the middle, all the springs get deformed a little, not just the ones adjacent to my finger. Of course my characterization could be completely wrong since I know very little about the nature of covalent bonds :) - Sanjeev Singh

even so, doesnt the force somehow need to be transmitted to the sides? in that case, it would have to be transmitted through the set of bonds nearest to the pencil tip, which is fairly small - not sure there is anyway for it to bypass that limitation, and so youd still be limited to their maximal holding force. - bob

I'm not sure how accurately this translates into the 2D case, but in the 1D case, if I remember my static physics correctly, if you have a string suspended between two points and you press down in the middle, the tension will be the same at every point in the string, so it won't break at the point you press on, but on the weakest part of the whole string. - Sanjeev Singh

That obviously doesn't translate directly to 2D since a fabric can have holes without tearing completely. - Jim Norris

Robbie, Are you worried about the local pressure at the pencil tip? How big do you think the pencil tip area would need to be before it is not a problem for the covalent bonds? Also, do you think the material or the pencil would fail there? It seems like if this is the strongest material in the world, you would always have failure in your "pencil" unless it was also made out of this material. And compression works a bit differently than tension, so it is unclear how even the same material would perform. - Clare Dibble

my thought was that a sheet a single molecular layer thick isnt likely to be very strong (in macro scale terms), let alone hold up a car balanced on a pencil point (i didnt bother to think the pencil would fail first :P) - if you start scaling it up and making thicker sheets with the same (but scaled up) properties then you might have something interesting - otherwise it remains a microscale curiosity - id be impressed if the single-atom thick sheet could support a pencil on its side- apparent levitation :) - bob

I also disagree with the hand-wavy "If we could scale it to large size". Most materials are strong when they're very small, and get dramatically weaker as they get larger. This tells us nothing about how much stronger it is than, say, steel. - Alex Power