Featured Research

from universities, journals, and other organizations

Unlike Rubber Bands, Molecular Bonds May Not Break Faster When Pulled

Date:
June 22, 2009
Source:
University of Illinois at Urbana-Champaign
Summary:
From balloons to rubber bands, things always break faster when stretched. Or do they? Scientists studying chemical bonds now have shown this isn't always the case, and their results may have profound implications for the stability of proteins to mechanical stress and the design of new high-tech polymers.

Research led by chemistry professor Roman Boulatov contradicts the intuitive notion that molecules -- like rubber bands -- break faster when pulled.
Credit: L. Brian Stauffer

From balloons to rubber bands, things always break faster when stretched. Or do they? University of Illinois scientists studying chemical bonds now have shown this isn't always the case, and their results may have profound implications for the stability of proteins to mechanical stress and the design of new high-tech polymers.

Related Articles


"Our findings contradict the intuitive notion that molecules are like rubber bands in that when we pull on a chemical bond, it should always break faster," said chemistry professor Roman Boulatov, who led the study. "When we stretch a sulfur-sulfur bond, for example, how fast it breaks depends on how the nearby atoms move."

The findings also contradict the conventional interpretation of experimental results obtained by other researchers studying the fragmentation rate of certain proteins containing sulfur-sulfur bonds when stretched with a microscopic force probe. In those experiments, as the force increased, the proteins fragmented faster, leading the researchers to conclude that as the sulfur-sulfur bond was stretched, it reacted faster and broke faster.

"Our experiments suggest a different conclusion," Boulatov said. "We believe the acceleration of the fragmentation was caused by a change in the protein's structure as it was stretched, and had little or nothing to do with increased reactivity of a stretched sulfur-sulfur bond."

In their experiments, the researchers use stiff stilbene as a molecular force probe to generate well-defined forces on molecules atom by atom.

The probe allows reaction rates to be measured as a function of the restoring force. Similar to the force that develops when a rubber band is stretched, the molecular restoring force contains information about how much the molecule was distorted, and in what direction.

In previous work, when Boulatov's team pulled on carbon-carbon bonds with the same force they would later apply to sulfur-sulfur bonds, they found the carbon-carbon bonds broke a million times faster than when no force was applied.

"Because the sulfur-sulfur bond is much weaker than the carbon-carbon bond, you might think it would be much more sensitive to being pulled on," Boulatov said. "We found, however, that the sulfur-sulfur bond does not break any faster when pulled."

Boulatov and his team report their findings in a paper accepted for publication in Angewandte Chemie, and posted on the journal's Web site.

"When we pulled on the sulfur-sulfur bond, the nearby methylene groups prevented the rest of the molecule from relaxing," Boulatov said, "thus eliminating the driving force for the sulfur-sulfur bond to break any faster."

Chemists must bear in mind that even in simple chemical reactions, such as a single bond dissociation, "we must take into account other structural changes in the molecule," Boulatov said. "The elongation alone, which occurs when a bond is stretched, does not represent the full picture of what happens when the reaction occurs."

The good news, Boulatov said, is that not every polymer that is stretched will break faster. "We might be able to design polymers, for example, that would resist fragmentation under modest mechanical stresses," he said, "or will not break along the stretched direction, but in some other desired direction."

With Boulatov, co-authors of the paper are graduate student and lead author Timothy Kucharski, research associate Qing-Zheng Yang, postdoctoral researcher Yancong Tian, and graduate students Zhen Huang, Nicholas Rubin and Carlos Concepcion.

Funding was provided by the National Science Foundation, the U.S. Air Force Office of Scientific Research, the American Chemical Society Petroleum Research Fund, and the U. of I.


Story Source:

The above story is based on materials provided by University of Illinois at Urbana-Champaign. Note: Materials may be edited for content and length.


Cite This Page:

University of Illinois at Urbana-Champaign. "Unlike Rubber Bands, Molecular Bonds May Not Break Faster When Pulled." ScienceDaily. ScienceDaily, 22 June 2009. <www.sciencedaily.com/releases/2009/06/090617123656.htm>.
University of Illinois at Urbana-Champaign. (2009, June 22). Unlike Rubber Bands, Molecular Bonds May Not Break Faster When Pulled. ScienceDaily. Retrieved March 5, 2015 from www.sciencedaily.com/releases/2009/06/090617123656.htm
University of Illinois at Urbana-Champaign. "Unlike Rubber Bands, Molecular Bonds May Not Break Faster When Pulled." ScienceDaily. www.sciencedaily.com/releases/2009/06/090617123656.htm (accessed March 5, 2015).

Share This


More From ScienceDaily



More Matter & Energy News

Thursday, March 5, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Gas Production Cut on Earthquake Fears

Gas Production Cut on Earthquake Fears

Reuters - Business Video Online (Mar. 5, 2015) The Dutch government has cut production at Europe&apos;s largest gas field in Groningen amid concerns over earthquakes which are damaging local churches. As Amy Pollock reports the decision - largely politically-motivated - could have big economic conseqeunces. Video provided by Reuters
Powered by NewsLook.com
Star Wars-Inspired Prototype Creates Holographic Display

Star Wars-Inspired Prototype Creates Holographic Display

Reuters - Innovations Video Online (Mar. 5, 2015) A prototype holographic display named Leia - after the Star Wars princess who appeared in holographic form asking Obi-Wan Kenobu for help - is demonstrated at the Mobile World Congress in Barcelona. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
IKEA and Samsung Launch Embedded Wireless Charging Range

IKEA and Samsung Launch Embedded Wireless Charging Range

Reuters - Innovations Video Online (Mar. 5, 2015) Samsung and IKEA hope their new embedded wireless charging products, launched at Barcelona&apos;s Mobile World Congress, will tempt consumers eager for plugless power. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com
Samsung Unveils $30,000 'Dream Doghouse'

Samsung Unveils $30,000 'Dream Doghouse'

Buzz60 (Mar. 5, 2015) On display at the Crufts dog show in England, the &apos;dog kennel of the future&apos; comes with features like a doggie treadmill and Samsung tablet. Mike Janela (@mikejanela) has more. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins