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24 April 2014 11:45 am ,
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Major climate data sets have underestimated the rate of global warming in the last 15 years owing largely to poor data...
The tsetse fly is best known as the vector for the trypanosome parasites that cause sleeping sickness and a disease in...
The National Institutes of Health is revising its "two strikes" rule, which allowed researchers only one chance to...
By stabilizing the components of retromers, molecular complexes that act like recycling bins in cells, a recently...
Fossil fuels power modern society by generating heat, but much of that heat is wasted. Semiconductor devices called...
Researchers are gaining insights into what made Supertyphoon Haiyan so powerful and devastating through post-storm...
Millions around the world got a first-hand look at what it was like to be in Tacloban while it was pummeled by...
- 24 April 2014 11:45 am , Vol. 344 , #6182
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Rumpelstiltskins of the Nanoworld
17 November 2000 7:00 pm
Laboring like modern-day Rumpelstiltskins, scientists have successfully spun submicroscopic carbon nanotubes into nearly pure carbon thread. The precious strands may one day be woven into energy-storing bulletproof vests for Robocop-like soldiers or lightweight cables that tether satellites to Earth.
To make a nanotube, take a hexagonal mesh sheet of carbon atoms and roll it up like a sheet of paper into a tube a few micrometers long and about 1 nanometer wide. Then cap each end with one-half of a buckyball, the spherical 60-atom carbon balls that resemble Buckminster Fuller's geodesic dome. This surprisingly simple cigar-shaped structure is pound for pound the strongest material known. "On a weight basis, a single carbon nanotube is at least 50 times stronger than steel wire," says chemist Philippe Poulin of the Research Center Paul Pascal--CNRS in Pessac, France. When a solution of nanotubes dries out, the tubes stick together and form sheets called "buckypaper." But buckypaper retains only a small fraction of the remarkable strength of the individual tubes. And you can't weave sheets of paper--for that you need thread.
Now, Poulin and his collaborators have found they can spin out silklike strands of carbon by injecting a carefully prepared solution of nanotubes into a rotating solution containing polyvinyl alcohol. If the initial concentration of nanotubes is just right, the stream turns into a mesh ribbon that later collapses into a thread when removed from the spinning bath. Although these fibers don't match individual tubes, Poulin says, they're about three times more difficult to stretch than high-strength nylon fibers.
The fibers should get much stronger as researchers improve the process. "We are not anywhere close to [having] the fibers that will eventually come out," says physicist Richard Smalley of Rice University in Houston, the co-discoverer of buckyballs. "The next year will see a lot of excitement in this field." Already, materials scientist Ray Baughman's group at Honeywell International in Morristown, New Jersey, has spun more durable fibers with a modification of the Poulin group's method; several other teams have also started producing nanotube threads.