Nanotechnology Now







Heifer International

Wikipedia Affiliate Button


DHgate

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

Chromium-Centered Cycloparaphenylene Rings as New Tools for Making Functionalized Nanocarbons February 24th, 2015

Building tailor-made DNA nanotubes step by step: New, block-by-block assembly method could pave way for applications in opto-electronics, drug delivery February 23rd, 2015

Half spheres for molecular circuits: Corannulene shows promising electronic properties February 17th, 2015

SouthWest Nanotechnologies CEO Dave Arthur Appointed to the Board of Affiliates of Rice University Professional Science Master’s Program February 13th, 2015

Discoveries

Moving molecule writes letters: Caging of molecules allows investigation of equilibrium thermodynamics February 27th, 2015

Untangling DNA with a droplet of water, a pipet and a polymer: With the 'rolling droplet technique,' a DNA-injected water droplet rolls like a ball over a platelet, sticking the DNA to the plate surface February 27th, 2015

Real-time observation of bond formation by using femtosecond X-ray liquidography February 26th, 2015

Graphene shows potential as novel anti-cancer therapeutic strategy: University of Manchester scientists have used graphene to target and neutralise cancer stem cells while not harming other cells February 26th, 2015

Materials/Metamaterials

Moving molecule writes letters: Caging of molecules allows investigation of equilibrium thermodynamics February 27th, 2015

Graphene shows potential as novel anti-cancer therapeutic strategy: University of Manchester scientists have used graphene to target and neutralise cancer stem cells while not harming other cells February 26th, 2015

In quest for better lithium-air batteries, chemists boost carbon's stability: Nanoparticle coatings improve stability, cyclability of '3DOm' carbon February 25th, 2015

Learning by eye: Silicon micro-funnels increase the efficiency of solar cells February 25th, 2015

Announcements

Moving molecule writes letters: Caging of molecules allows investigation of equilibrium thermodynamics February 27th, 2015

Untangling DNA with a droplet of water, a pipet and a polymer: With the 'rolling droplet technique,' a DNA-injected water droplet rolls like a ball over a platelet, sticking the DNA to the plate surface February 27th, 2015

Bruker-Sponsored Sixth AFM BioMed Conference Highlights Increasing Impact of AFM in Biological Applications February 26th, 2015

Graphene shows potential as novel anti-cancer therapeutic strategy: University of Manchester scientists have used graphene to target and neutralise cancer stem cells while not harming other cells February 26th, 2015

Human Interest/Art

2015 Nanonics Image Contest January 29th, 2015

OCSiAl supports NanoART Imagery Contest January 23rd, 2015

EnvisioNano: An image contest hosted by the National Nanotechnology Initiative (NNI) January 22nd, 2015

Oxford Instruments Asylum Research Announces AFM Image Contest Winners January 11th, 2015

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 1999-2015 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE