Subscribe free to our newsletters via your
. 24/7 Space News .




TECH SPACE
Molecular levers may make materials better
by Staff Writers
Durham, NC (SPX) Dec 26, 2012


illustration only

In a forced game of molecular tug-of war, some strings of atoms can act like a lever, accelerating reactions 1000 times faster than other molecules. The discovery suggests that scientists could use these molecular levers to drive chemical and mechanical reactivity among atoms and ultimately engineer more efficient materials.

"We are interested in designing new, stress-responsive materials, so we are trying to develop reactions that are very slow normally but that can be accelerated efficiently by force," said Duke chemist Steve Craig, who headed the research.

In recent experiments, Craig and his team found that a molecule made with a polynorbornene backbone can act as a lever to open a ring embedded within the molecule 1000 times faster than a similar ring being tugged at on a polybutadiene scaffold. The results, which appear Dec. 23 in Nature Chemistry, suggest that a simple change in the backbone may affect the how fast mechanically assisted reactions occur.

Scientists are interested in this type of molecular tug-of-war because many materials break down after repeated cycles of tugging, stress and other forces.

"If we can channel usually destructive forces into constructive pathways, we could trigger reactions that make the material stronger when and where it is most useful," Craig said. Researchers might then be able to extend the material's lifetime, which might in the long term have applications ranging from composites for airplane frames to biomedical implants.

In the experiment, Craig, who is a professor and chair of the chemistry department, and his team used the equivalent of microscopic tweezers to grab onto two parts of atomic chains and pulled them so that they would break open, or react, in certain spots.

The team predicted that one molecule would react more efficiently than the other but was surprised to find that the force-induced rates differed by three orders of magnitude, an amount that suggests that the polynorbornene backbone can actually accelerate forced reactions the way a crowbar quickens pulling a nail from a wall.

Craig said changes to the molecular group undergoing the reaction may have a much smaller effect than changes to nearby, unreactive molecules like those on the backbone.

It is also a good starting point to identify other molecular backbones that are easy to make and have the largest response to changes in nearby reactions, features Craig said might help in developing even better, more responsive materials.

The research was supported by the U.S. Army Research Laboratory, the Army Research Office and National Science Foundation. "A Backbone Lever Arm Effect Enhances Polymer Mechanochemistry." (2012) Klukovich, H. et al. Nature Chemistry. AOP. DOI: 10.1038/NCHEM.1540

.


Related Links
Duke University
Space Technology News - Applications and Research






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle








TECH SPACE
China rare earths producer extends output halt
Beijing (AFP) Dec 25, 2012
China's largest rare earths producer said Tuesday it would suspend output at some plants for another month, extending a halt started in late October to try and stem falling prices. Baotou Steel Rare-Earth will halt firing, smelting and separation of rare earths at its factories in Baotou in the northern region of Inner Mongolia for one more month, it said in a statement filed with the Shangh ... read more


TECH SPACE
GRAIL Lunar Impact Site Named for Astronaut Sally Ride

NASA probes crash into the moon

No plans of sending an Indian on moon

Rocket Burn Sets Stage for Dynamic Moon Duos' Lunar Impact

TECH SPACE
Clays on Mars: More Plentiful Than Expected

Opportunity For Some Shoulder Workout At Copper Cliff

Enabling ChemCam to Measure Key Isotopic Ratios on Mars and Other Planets

Curiosity Rover Explores 'Yellowknife Bay'

TECH SPACE
NASA Puts Orion Backup Parachutes to the Test

White House to honor scientists, inventors

TDRS-K Arrives at Kennedy for Launch Processing

Sierra Nevada Corporation Selected by NASA to Receive Human Spaceflight Certification Products Contract

TECH SPACE
Mr Xi in Space

China plans manned space launch in 2013: state media

China to launch manned spacecraft

Tiangong 1 Parked And Waiting As Shenzhou 10 Mission Prep Continues

TECH SPACE
New ISS crew docked at Space Station

Expedition 34 Spends Christmas in Space

Three astronauts blast off for ISS in Russian craft

Soyuz rocket brings trio to space station

TECH SPACE
Ariane 5 ECA orbits Skynet 5D and Mexsat Bicentenario satellites

Payload integration complete for final 2012 Ariane 5 mission

Arctic town eyes future as Europe's gateway to space

ISRO planning 10 space missions in 2013

TECH SPACE
Closest sun-like star may have planets

Nearby star is good candidate for Earth-like planets

Venus transit and lunar mirror could help astronomers find worlds around other stars

Astronomers discover and 'weigh' infant solar system

TECH SPACE
2012: Consumer tech takes center stage

Molecular levers may make materials better

Netflix blames Amazon for Christmas Eve outage

Turbopump Bearing Blamed For Failed Russian Comsat Orbiting




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement