Tikalon Blog by Dev Gualtieri

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Roll Your Own Nanotubes

March 1, 2012

One of my uncles used to roll his own cigarettes . It wasn't for an aesthetic reason, but because it was cheaper. It's not that manufacturing a cigarette from its component parts is difficult. There was a huge tax on them at the time, which is much larger now, but a smaller tax on canned tobacco .

His cigarettes were made on a small, manually-operated machine as you would expect them to be made, by rolling a rectangular sheet of thin paper along one axis with the tobacco inside. There is, however, another way to make paper tubes, which is evidenced in the thin cardboard tubes that can be found in your household toilet paper . In those tubes, a much longer sheet is twisted into a helix until the edges join and are sealed.[1]

Figure 1 of US Patent No. 238,640, 'Cigarette-Machine,' by James A. Bonsack, March 8, 1881

Not my uncle's manual cigarette roller.

Figure 1 of US Patent No. 238,640, "Cigarette-Machine," by James A. Bonsack, March 8, 1881.

Not surprisingly, Bonsack was from Roanoke, Virginia

(Via Google Patents).[2]

That twisting trick appears to be a possible method of using graphene nanoribbons to produce lengthy carbon nanotubes . I wrote about nanoribbons of graphene and boron nitride in two previous articles (Graphene Transistors, October 21, 2010 and Boron Nanoribbons, January 11, 2012 ). Computer simulations of this process are reported in a recent issue of Physical Review B by a team of physicists from the NanoScience Center , Department of Physics , University of Jyväskylä (Jyväskylä, Finland) and the School of Engineering and Applied Sciences , Harvard University (Cambridge, Massachusetts).[3-5]

It's not surprising that carbon nanotubes are easily made, but difficult to make to specification. You get a range of tube diameters and structures. In particular, the way that the carbon units are wrapped, the chirality , determines whether the tubes are semiconducting or metallic .[5]

Graphene, which was originally studied as exfoliated flakes from graphite , has also been made by chemically scissoring carbon nanotubes. Perhaps the inverse process is possible; namely, rolling graphene sheets into tubes. If the direction of rolling with respect to the sheet's crystalline orientation can be controlled, such a process would produce long nanotubes of particular chirality.[5]

The Harvard-University of Jyväskylä team used quantum molecular dynamic simulations to model the process. Their calculations show that the carbon atoms at the edge of a graphene ribbon will bond to atoms on the opposite edge when the ribbon is sufficiently twisted, thereby creating the nanotube.[3-5] The transformation from sheet to tube proceeds by an intermediate buckling that's aided by the elasticity of the carbon-carbon bond in the graphene sheet.

Rolling a graphene ribbon into a tube.

Rolling a graphene ribbon into a tube. In this example, a ribbon of 38 nm length is formed into a tube by external clamping. It holds its shape after the clamp is removed (lowest figure). Figure 7 of ref. 3 (modified), via the (arXiv Preprint Server).

Although the calculations were for graphene nanoribbons, the method may generalize to other materials, such as the boron nitride that I mentioned earlier.[3,4] It may also simplify the encapsulation of other materials inside carbon nanotubes.[3-5]

These results were from a computer simulation, but how would you do such a thing experimentally ? I would likely attached some polarizable molecules to the ends of the nanoribbon and use an oscillating electric field , along with a little inertia , to snap the ribbons into tubes.

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