|Quoting NoWorries (Reply 8):|
The other issue would be flexibility -- do the sheets retain their superconductivity when they flex?
I believe that to within certain tolerances, yes.
The superconductivity of graphene is hardly a surprise. Graphene is basically a bunch of benzene rings stuck together edge-to-edge.
In a benzene ring, there are six carbon atoms. Each has three sp2 orbitals projecting out of it in a planar configuration with even spacing of 120°. Two of these sp2 orbitals contact sp2 orbitals on adjacent carbon atoms and the third contacts a hydrogen atom on the outside of the benzene ring.
In the above image, you can see how those sp2 orbitals are arranged. But the thing is that each of these orbitals is discrete. Electrons cannot move from one sp2 orbital to another.
But there is a 4th orbital, called a p orbital that extends at 90° angle to the plane of the sp2 orbitals. One lobe on each face of the ring. Typically, each of these orbitals is occupied by one electron. But when in the form of a benzene ring, the orbitals merge together to form a single, large "delocalized" orbital that exists in a ring on each facet of the benzene molecule. Unlike the sp2 orbitals, electrons can move freely through the entire delocalized orbital created in the benzene ring.
This diagram shows the basic idea:
, now consider this: in a graphene sheet, it's basically a bunch of benzene molecules but instead of hydrogen atoms on the outside, each carbon atom is bonded to another carbon. Thus:
So you can see how now the p orbitals could be delocalized across the entire sheet of graphene. In other words, the orbital of any given electron is the entire sheet! This means that electrons can travel freely across the sheet and, indeed, behave as if they were massless photons. It is also obvious, with this explanation, as to why graphene conducts electricity in one direction only.
A strong enough bend in the sheet might disrupt the orbitals enough to suppress this phenomenon, but I don't think that the sorts of bends that you would see in a typical power line would be enough to cause a disruption of the common orbital. I know that buckytubes are strongly conductive and that they are also being worked on as potential superconductors, but they are most certainly bent at far higher angles than you would ever see in a graphene wire, so clearly some bend is tolerable.