New Hampshire Startup Makes World’s Largest Sheets of Carbon Nanotubes

2/22/08

Ever since scientists first figured out how to make carbon nanotubes—tiny cylinders of carbon with diameters of a few tens of nanometers—they’ve been touted as the material of the future: as strong as steel but far lighter, with the ability to conduct electricity in useful ways. The problem is that because they’re so small, it’s been difficult to make them at scales that would be useful to industry. You can’t really build a lightweight airplane a few microns at a time, after all.

Now a New Hampshire company, Nanocomp Technologies of Concord, says it has overcome that limitation, producing sheets of carbon nanotubes that measure three feet by six feet and promising slabs 100 square feet in area as soon as this summer.

“From the get-go, we wanted to build something that would be manufacturable,” says Peter Antoinette, CEO and co-founder of Nanocomp. “We’re out to make value-added components out of that material.”

The sheets, which the company can produce on its single machine at a rate of one per day, are composed of a series of nanotubes each about a millimeter long, overlapping each other randomly to form a thin mat. The tensile strength of the mat ranges from 200 to 500 megapascals—a measure of how tough it is to break. A sheet of aluminum of equivalent thickness, for comparison, has a strength of 500 megapascals. If Nanocomp takes further steps to align the nanotubes, the strength jumps to 1,200 megapascals.

The trick, says Antoinette, is being able to make the tubes a millimeter long. Many carbon nanotubes, in addition to having vanishingly tiny diameters, are at best a few tens of microns long (a micron is one-thousandth of a millimeter). So most production processes create what is essentially a powder of nanotubes, Antoinette says.

Equipment Room at Nanocomp TechnologiesHe won’t go into great detail about Nanocomp’s recipe for cooking up the tubes, but essentially the process works by taking a carbon-containing fuel, such as ethanol or methane, heating it up, and flowing it past a catalyst—a nanoparticle that can be made from any number of materials, including oxides of nickel, cobalt, or iron. Heat causes the flowing fuel to react with the catalyst, breaking off the carbon atoms, which build up on the catalyst, atom by atom, into a nanotube. The size of the catalyst determines the diameter of the nanotube.

Antoinette says Nanocomp’s technical achievement was to figure out a way to maintain the catalyst particle at the desired size and hold it stable long enough for the nanotube to grow to millimeter length. A computer controlling about 30 different parameters in the process—including temperature, temperature gradient, gas flow rates, and the chemistry of the mix—allows the builders to control the properties of the tubes. One setting gives them single-walled tubes, and another gives multi-walled versions, with one cylinder inside another, which provide different properties. “We can dial it in,” he says.

So what do you do with the stuff once you’ve made it? Antoinette says the sheets would be particularly good for shielding electronic components from electromagnetic interference. He’s talked to manufacturers of cell phones and PDAs who are looking at the material as something they could use to build handsets that are less vulnerable to the noise from stray transmissions. It might also make a nice housing for a computer, with aligned nanotubes acting as an antenna for wireless connections and randomly oriented nanotubes protecting the computer from electrical surges, while the material also dissipates heat from the processor.

Someday Antoinette would like to see the nanotubes built into composites, similar to the carbon fiber composites being used for next-generation airplanes such as the Boeing 787. But even before that’s done, the current material can solve a problem designers are having with those carbon fiber composites—the fact that … Next Page »

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  • robert carrier

    You say that you are producing these “sheets” now at one per day what grade . are these SWCNT compared to what is being done and produced now in SWCNT and are they availble to industry.

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  • David

    So, it’s just barely as strong as Aluminum? Excuse me while I yawn.

  • Mark

    David:
    Yeah, but although they say the two sheets are the same strength the CNT sheet might be much lighter. Plus the idea is that the same technique will be applied to longer and longer CNTs resulting in much stronger sheets. Of course the big deal would be a MxN meter sheet where all the NTs are N meters long in one dimension and M in the other (ie the tubes span the sheet end to end with no breaks). What would really be cool would be tubes that intersect at fullerenes so that the two dimensions are bonded.
    Mark

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  • san

    Unwrap a nanotube, and you have a sheet of graphene. If you could create a sandwich composite of graphene layers, of MxN sq.meters in area, then it would likely have more strength than nanotube mats, since all the bonds would be in the same plane. Graphene is more of a wonder material than nanotubes are, and would give higher-strength sheets.

  • Peter

    I strongly suspect that the tensile strength quoted is actually a typo by the reporter. Either that or he got his facts seriously wrong. It is unfathomable to me how a sheet of carbon nanotubes would be LESS strong than an equivalent sheet of aluminum. And any company that created such a wimpy sheet of nanotubes sure wouldn’t be boasting about it.

  • guan

    I guess understanding the chemistry is important because there seems to be some confustion.

    the strength of these sheets comes entirely from weak van der waals and pi stacking forces. not covalent bonds. lots of covalent bonds (to other tubes) in a nanotube backbone completely destroy regularity and essentially change the properties so that you no longer have nanotubes.

    That is why the article said that the trick was growing the tubes long. if you have long tubes that overlap, held together with weak forces, the overlapping tubes will maintain a net end to end force holding the sheet together.

    if you add JUST the right amount of covalent bonds (like 4 bonds per tube) you will have the strongest lightest material ever made, Guaranteed.

    the difficulty lies in controlling the extent of reaction.

    I want to know if this company has developed a way to control stereoregularity.

    remember kids, a sheet of paper can be rolled up in a few different ways. remember kids, graphene looks different along 2 different axes in a plane. you can roll nanotubes up from the “corner” or from one side or the other. depending on how you roll it up you get different properties.

    if these guys have developed a way to make bulk nanotubes, with control of wall (single wall vs multiwall as multi wall are useless more of a structural material and single wall an electronic material), and stereoregulartiy, they will be the richest bastards ever…

    this is the same breakthrough that was made when people figured out you didnt need a mass spec to make fullerenes. in other words the price went from 1000 dollars per gram to 100 dollars per gram. researchers will be thrilled.

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  • http://www.mast-victims.org Henrik Eiriksson

    Quote:
    “Antoinette says the sheets would be particularly good for shielding electronic components from electromagnetic interference”

    Well, how about shielding humans from electromagnetic interference aswell? It’s a real problem and carbon-based EMF shielding is a real solution, like this: http://www.yshield.com
    I’m looking forward to this nanotech to become affordable to others than Boeing and Nasa.

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  • Paul

    Too bad, carbon nanotubes are toxic, take very good care while handling them.

    You have been warned!

    • dart

      Carbon Nanotubes are not toxic, the Problem is merely that early Generation tubes are so small that they can destroy your lungs, just like carbon dust in old coal-mines. Modern ones which are actually produced industrially und used are considerally longer

  • http://www.bostonrack.com Material Handling Equipment

    To recall, Carbon nanotubes are allotropes of carbon with a nanostructure that can have a length-to-diameter ratio greater than 1,000,000.
    Its better enough that the composition must be discuss clearly to know the possibilities of this technology. We must know the pros and cons of this.
    I guess understanding between chemistry and physics are very important in this aspect.

  • Stuart Halliday

    How can they be used as a substitute for copper wiring?

    Copper has a very low resistance per metre.

    Carbon isn’t anywhere near as low so you’ll need more power to send the signal through a length of carbon fibre.

    So an aircrafts power supply would need to be substantially bigger and heavier to compensate.

    • dart

      Carbon itself, yes, has higher resistance, but carbon nanotubes have been theoretical proven to have a 10 times lower electrical resistivity and a 1200 higher cnductiong capacity. Individual CNT haven been proven to achieve those values.

  • Fred Stone

    What is the stock symbol for Nanocomp?

  • http://67.101.40.35 Peter Marks

    Will someone please send me an email with the stock symbol for Nanocomp Technologies. This is a stock to buy for the long term.

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