Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Rice science news - Nanotube, heal thyself

Abstract:
Pound for pound, carbon nanotubes are stronger and lighter than steel, but
unlike other materials, the miniscule carbon cylinders remain remarkably
robust even when chunks of their bodies are blasted away with heat or
radiation. A Rice University study in the Feb. 16 issue of Physical Review
Letters offers the first explanation: tiny blemishes crawl over the skin of
the damaged nanotubes, sewing up larger holes as they go.

Rice science news - Nanotube, heal thyself

Houston, TX | Posted on February 15th, 2007

"The shape and direction of this imperfection does not change, and it never
gets any larger," said lead researcher Boris Yakobson, professor of
mechanical engineering and materials science and of chemistry. "We were
amazed by it, but upon further study we found a good explanation. The atomic
irregularity acts as a kind of safety valve, allowing the nanotube to
release excess energy, in much the way that a valve allows steam to escape
from a kettle."

The research appears Feb. 16 issue of in Physical Review Letters.

Carbon nanotubes are hollow cylinders of pure carbon that measure about a
billionth of a meter, or one nanometer, across. They are much longer than
they are wide, akin in shape to 100-foot garden hose, and they're 100 times
stronger than steel at one-sixth the weight.

The carbon atoms in nanotubes are joined together in six-sided hexagons, so
when scientists sketch out the arrangement on paper, nanotubes look
something like a rolled up tube of chicken wire. Yakobson's "smart repair
machine" is a deformity, a blemish in this pattern. The blemish consists of
a five-sided pentagon joined to a seven-sided heptagon and contains a total
of ten atoms. Yakobson, who specializes in using computers to decipher the
atomic pecularities of materials, discovered several years ago that
mechanically stressed nanotubes - like those being pulled very hard from
both ends - are predisposed to develop these 5/7-defects due to the complex
interplay of thermodynamic forces at work in the nanotube.

In the latest study, Yakobson, research associate Feng Ding and students
examined the effects of other types of stress, including exposure to heat
and radiation. The tests confirmed the predisposition of nanotubes to
develop the 5/7 blemishes, and they revealed the blemishes' unexpected
healing powers.

"The 5/7-blemishes move across the surface of the nanotube like a steamship,
giving off puffs of carbon gas," said Ding. "In their wake, the skin of the
tube appears pristine, in its characteristic hexagonal arrangement."

Yakobson said the blemishes consume all larger defects, and chug along
indefinitely, rearranging atoms and healing the skin of the damaged
nanotubes. This explains how nanotubes retain their strength, even when
severely damaged. But the healing comes with a price.

"In their role as a safety valve, the 57-steamers give off energy and mass,
which is released as pairs of gaseous carbon atoms," Yakobson said. "Since
they never change shape or stop moving, they ever so slowly eat away the
surface of the nanotube, one pair of atoms at a time."

Yakobson said the 5/7-blemishes turn when they reach the end of the nanotube
and return in the opposite direction. In fact, there's only one thing that
can stop them: another 5/7 blemish. If two of the blemishes run headlong
into one other, they cancel each other out and disappear.

Research co-authors include graduate students Kun Jiao and Mingqi Wu.

The research was supported by the Office of Naval Research, the National
Science Foundation and the Robert A. Welch Foundation.

####

About Rice University
Rice University is consistently ranked one of America’s best teaching and
research universities. It is distinguished by its: size—2,850 undergraduates
and 1,950 graduate students; selectivity—10 applicants for each place in the
freshman class; resources—an undergraduate student-to-faculty ratio of
6-to-1, and the fifth largest endowment per student among American
universities; residential college system, which builds communities that are
both close-knit and diverse; and collaborative culture, which crosses
disciplines, integrates teaching and research, and intermingles
undergraduate and graduate work. Rice’s wooded campus is located in the
nation’s fourth largest city and on America’s South Coast.

For more information, please click here

Contacts:
Jade Boyd
713-348-6778

Copyright © Rice University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Nanotubes/Buckyballs

A sponge-like molecular cage for purification of fullerenes December 15th, 2014

'Trojan horse' proteins used to target hard-to-reach cancers: Scientists at Brunel University London have found a way of targeting hard-to-reach cancers and degenerative diseases using nanoparticles, but without causing the damaging side effects the treatment normally brings December 11th, 2014

Detecting gases wirelessly and cheaply: New sensor can transmit information on hazardous chemicals or food spoilage to a smartphone December 8th, 2014

Green meets nano: Scientists at TU Darmstadt create multifunctional nanotubes using nontoxic materials December 3rd, 2014

Discoveries

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Instant-start computers possible with new breakthrough December 19th, 2014

Creation of 'Rocker' protein opens way for new smart molecules in medicine, other fields December 18th, 2014

Iranian Scientists Use Nanotechnology to Increase Power, Energy of Supercapacitors December 18th, 2014

Materials/Metamaterials

Aculon Hires New Business Development Director December 19th, 2014

ORNL microscopy pencils patterns in polymers at the nanoscale December 17th, 2014

Pb islands in a sea of graphene magnetise the material of the future December 16th, 2014

Graphene Applied in Production of Recyclable Electrodes December 13th, 2014

Announcements

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Instant-start computers possible with new breakthrough December 19th, 2014

Aculon Hires New Business Development Director December 19th, 2014

Iranian Scientists Use Nanotechnology to Increase Power, Energy of Supercapacitors December 18th, 2014

Human Interest/Art

Longhorn beetle inspires ink to fight counterfeiting November 5th, 2014

Iran-Made Respiratory Nano Masks Provided to Hajj Pilgrims October 23rd, 2014

Japanese gold leaf artists worked on a nano-scale: Study demonstrates X-ray fluorescence spectroscopy is a non-destructive way to date artwork July 3rd, 2014

Harry Potter-style invisibility cloaks: A real possibility next Christmas? Forget socks and shaving foam, the big kids of tomorrow want an invisible cloak for Christmas December 19th, 2013

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More










ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE