The beginning of this story has been told many times. In 1985, a confluence of events led to an unexpected and unplanned experiment with a new kind of microscope resulting in the discovery of a new molecule made purely of carbon – the very element chemists felt there was nothing more to learn about. Buckyballs – sixty carbon atoms arranged in a soccer ball shape – had been discovered and the chemical world, not to mention the physical and material worlds, would never be the same.
Graphene

To understand why buckytubes have the incredible properties they do, we must first look at the building blocks of the tubes. Start by considering graphite. While long considered the poor brother of diamond in the family tree, graphite turns out to be far richer in its properties. Like the entrepreneurial son who never went to college, yet exceeded all expectations, graphite has, despite its unimpressive appearances, struck it rich. But, for this purpose, we’ll focus on a single layer of graphite, called graphene, in which the carbon atoms are arranged in hexagons, just like chicken-wire. Graphene has the distinction of being the densest known two-dimensional packing of atoms. No 2-D slice through diamond, or any other material, is denser on an atomic basis. This, together with the special nature of the carbon-carbon bonds in this network, gives graphene the highest stiffness of any sheet.
Mechanical Properties

Now take this sheet and wrap it up into a tube by seamlessly connecting two opposite edges. You now have a tube with the greatest stiffness, both in tension and in bending. Many materials are stiff (although not as stiff as this), but so brittle as to be often useless. (Likewise, most materials that are not brittle, such as spider silk, which can be stretched about 30% beyond its resting length, are not particularly strong.) Buckytubes, stiff as they are, are also amazingly tough: they can stretch beyond 20% of their resting length, and can be bent over double, and even tied into a knot and released with no resulting defect! This unprecedented combination of stiffness and toughness makes buckytubes by far the strongest known fibres in tension – about 100 times stronger than high-strength steel at one-sixth the weight! This is remarkable stuff.