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Simple and Inexpensive Fabrication of Very Long Carbon Nanotubes

IB-1719

APPLICATIONS OF TECHNOLOGY:

     
   
  TEM (200 keV, JEOL 200 CX microscope) images of carbon nanotubes.  
     
  • Field emitters, high-strength fibers, strong radiation shields, energy absorbing materials, nano-scale catalytic beds, efficient gas storage, nano-circuits, and nano-scale transistors
  • Nano-sized, frictionless bearings
  • Nano-mechanical, electro-mechanical, and opto-electronic devices

ADVANTAGES:

  • Low Fabrication Temperature
  • High Yield
  • Short Fabrication Time
  • High Purit

ABSTRACT:

K.P. Vollhardt of Berkeley Lab and his colleague V. S. Lyer have devised a simple, inexpensive, high-yield process requiring no special apparatus for fabrication of high-quality, very long carbon nanotubes with narrow diameter distribution. This method improves upon existing arc discharge, laser ablation, and chemical vapor deposition (CVD) methods, all of which have various problems, including lack of control of catalyst/precursor ratios in starting materials and products; the need for fabrication of specialized apparatus; limited area coverage of nanotube mats (which translates into a low yield); and the need for overly high temperatures for fabrication.

This new process successfully fabricates large-area, freestanding films of very long carbon nanotubes by heating a transition metal complexed alkyne with aryl and/or alkyl substituents. The heating of the transition metal complex can be completed in 0.5 to 3.0 hours at 550–700°C in a sealed vessel under partial pressure of argon or helium (in contrast to typical chemical vapor deposition, which involves a flow of organic compound over a transition metal catalyst). The heating results in high yields of carbon nanotubes as freestanding films or nanotubes mats, which can be simply lifted off the inside of the vessel. Coverage of areas more than 4cm2 have been achieved from about 30 mg of the starting complex. Compared to other processes, the yields are essentially quantitative. The removal of the transition metal from the films is a simple process, achieved by immersing the film in aqueous hydrochloric acid and filtering out the dissolved metal. This allows for greater purity in the final carbon nanotube yield.

STATUS:

Issued Patent #7,261,871. Available for licensing or collaborative research.

REFERENCE NUMBER: IB-1719

FOR ADDITIONAL INFORMATION, SEE:

Dosa, P. I.; Erben, C.; Iyer, V. S.; Vollhardt, K. P. C.; Wasser, I. M., "Metal Encapsulating Carbon Nanostructures from Oligoalkyne Metal Complexes," J. Am. Chem. Soc. 1999, 121, 10430.

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Last updated: 04/30/2013