Category: Nanoscale Bulk Technologies

brianwang writes "The longstanding promise of superfortified heat-conducting materials has become a reality. University of Pennsylvania scientists have determined that adding a relatively small number of carbon nanotubes to epoxy yields a compound three-and-a-half times as hard and far better at heat conductance than the product found in hardware stores. The researchers report their successful tinkering with the commonplace adhesive in the April 15 issue of the journal Applied Physics Letters. Led by Penn physicist Alan T. "Charlie" Johnson, the team created a composite of 95 to 99 percent common epoxy mixed with 1 to 5 percent carbon nanotubes, filaments of carbon less than one-ten-thousandth the width of a human hair. "These findings add considerably to carbon nanotubesí luster as possible additives to a variety of materials," said Johnson, an associate professor of physics and astronomy at Penn. "In addition to adhesives such as epoxy, we are looking at nanotube-based greases that might be used to carry heat away from electronic chips." Johnsonís group determined that epoxy doped with nanotubes showed a 125 percent increase in thermal conductivity at room temperature. "This is the first published report of enhanced thermal conductivity in a material owing to the addition of carbon nanotubes and the first demonstration of simultaneous thermal and mechanical enhancement of a real-world material," Johnson said. Epoxy is an attractive target for fortification with carbon nanotubes, Johnson said, because itís relatively easy to mix the minuscule filaments into it, and there are clear industrial benefits in a harder, better-conducting epoxy. Other scientists have attempted to fortify epoxy with carbon nanotubes, but Johnsonís group succeeded in dispersing the nanotubes more evenly. http://www.eurekalert.org/pub_releases/2002-04/uop -net041502.php"

Gina Miller writes "According to a press release (18 March 2002) from the University of Illinois at Urbana-Champaign, UI researchers and their collaborators at Harvard and Rice created superconducting wires using carbon nanotubes as scaffolding to support a molybdenum-germanium film as thin as one nanometer. The researchers demonstrated that the superconduction they observe is due to the film, and not to the nanotube, by using fluorinated carbon nanotubes, which, unlike ordinary carbon nanotubes, are not metallic.
For a report that multi-walled carbon nanotubes might themselves be superconducting at high temperatures, see previous Nanodot post Buckytubes may be high-temp superconductors (28 November 2001)."

Gina Miller writes "More on the magnetic properties of nanocrystals in United Press International's Nanotech could power future magnets (30 March 2002), an interview with Laura Henderson Lewis, materials scientist at Brookhaven National Laboratory's Department of Applied Science. "Tomorrow's supermagnets could be made of molecule-sized chunks of materials that normally would never interact, possibly creating magnetic fields strong enough to levitate trains at room temperature…" Lewis studies how magnetic materials perform and interact at the micro- and nano-scale, which involve groups of hundreds of atoms or even single molecules. Because magnetic atoms only affect other atoms a nanometer or so distant, engineering the structure of materials on the nanometer scale provides unique opportunities to control the magnetic properties of the materials. The methods mentioned for achieving nanometer scale control of structure are, however, not especially molecular – rapid solidification and milling with steel balls. For other coverage of nanomaterials research at Brookhaven National Laboratory, see Nanodot post of March 22, 2002 Brookhaven Lab launches nanomaterials research effort"

Mr_Farlops writes "Using nanorods and liquid plastic semiconductor, researchers at University of California, Berkeley, and the Lawrence Berkeley National Laboratory have created a solar cell that can be painted or sprayed onto a surface.

The Sacramento Bee article, which I found on Slash, was a bit short on details and perhaps incorrectly cites this discovery as an advance in nanotechnology."

[Editor's Note: Additional information, including some diagrams of the solar cells, can be found in this joint press release (28 March 2002) from the UC-Berkeley and LBL.

Additional coverage is available in an article from the Reuters News Service ("Group Makes Cheap Plastic Solar Energy Cells", 28 March 2002), and another from United Press International ("Researchers make plastic solar cells", 28 March 2002).]