Corporate Banner
Satellite Banner
Scientific Communities
Become a Member | Sign in
Home>News>This Article

A Step Toward Stronger Polymers

Published: Tuesday, November 06, 2012
Last Updated: Tuesday, November 06, 2012
Bookmark and Share
Counting loops that weaken materials could help researchers eliminate structural flaws.

Many of the objects we encounter are made of polymers — long chains of repeating molecules. Networks of polymers form manmade materials such as plastics, as well as natural products such as rubber and cellulose.

Within all of these polymeric materials, there are structural flaws at the molecular level. To form an ideal network, each polymer chain would bind only to another chain. However, in any real polymeric material, a significant fraction of the chains instead bind to themselves, forming floppy loops.

“If your material properties depend on having polymers connected to each other to form a network, but you have polymers folded around and connected to themselves, then those polymers are not part of the network. They weaken it,” says Jeremiah A. Johnson, an assistant professor of chemistry at MIT.

Johnson and his colleagues have now developed, for the first time, a way to measure how many loops are present in a given polymer network, an advance they believe is the first step toward creating better materials that don’t contain those weak spots.

Huaxing Zhou, an MIT postdoc, is the lead author of a paper describing the new technique in this week’s issue of the Proceedings of the National Academy of Sciences. Other authors are visiting researcher Jiyeon Woo, chemistry graduate student Alexandra Cok, chemical engineering graduate student Muzhou Wang, and Bradley Olsen, an assistant professor of chemical engineering.

Although polymer chemists have known about these loops since the 1940s, they have had no way to count them until now. In the new paper, the researchers measured the percentage of loops in a gel, but their approach could be used for nearly any type of polymer network, Johnson says.

To measure the number of loops, the researchers first design polymer chains that incorporate a chemical bond, in a specific location, that can be broken using hydrolysis. Once the polymer crosslinks into a gel network, the researchers treat it with a base that cleaves this chemical bond, known as an ester. (Other degradation methods, such as enzymes or light, could also be used.)

Because they know where the break points are, the researchers can predict the percentages of the four different degradation products they should expect to find in an ideal, no-loop network. By measuring the quantity of each degradation product and comparing it with the ideal, they can figure out what fraction of the polymer formed loops.

They found that the percentage of polymer loops ranges from about 9 percent to nearly 100 percent, depending on the concentration of polymers in the starting material and other factors.

“Even in the best material we can make, 9 percent of its junctions are wasted as loops, which tells us that if can figure out a way to reduce loop formation, we’d have a 9 percent improvement in material properties,” Johnson says.

Christopher Bielawski, a professor of chemistry at the University of Texas at Austin, says the new technique overcomes longstanding limitations in chemists’ understanding of the exact structures of polymers.

“The technique is a beautiful combination of experiment, theory and state-of-the-art analytics that takes the field a giant step toward sorting out a problem of tremendous importance,” says Bielawski, who was not part of the research team.

The researchers are now looking for ways to reduce the number of loops by altering the mixture of polymers used to produce a material, as well as the reaction conditions. They are also planning to use their method to study interactions between cells and biological materials. It has already been shown that at the micron scale, cells behave differently depending on the mechanical properties of their environment, such as stiffness.

In their new studies, the MIT researchers want to look at nanoscale interactions between cells and specific protein sequences found in the extracellular matrix, which provides structural support for cells.

The researchers hope to uncover what happens when a cell grabs on to a protein that is looped on itself rather than being attached to the extracellular matrix.

The research was funded by the MIT Department of Chemistry, MIT’s Institute for Soldier Nanotechnologies, and a National Defense Science and Engineering Graduate Fellowship.

Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,600+ scientific posters on ePosters
  • More Than 3,800+ scientific videos on LabTube
  • 35 community eNewsletters

Sign In

Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

Messing With The Monsoon
Manmade aerosols can alter rainfall in the world’s most populous region.
Friday, October 02, 2015
A Natural Light Switch
MIT scientists identify and map the protein behind a light-sensing mechanism.
Tuesday, September 29, 2015
Biologists Find Unexpected Role for Amyloid-Forming Protein
Yeast protein could offer clues to how Alzheimer’s plaques form in the brain.
Monday, September 28, 2015
How Flu Viruses Gain The Ability To Spread
New study reveals the soft palate is a key site for evolution of airborne transmissibility.
Friday, September 25, 2015
Viruses Join Fight Against Harmful Bacteria
Engineered viruses could combat human disease and improve food safety.
Friday, September 25, 2015
Targeting DNA
Protein-based sensor could detect viral infection or kill cancer cells.
Tuesday, September 22, 2015
Targeting DNA
Protein-based sensor could detect viral infection or kill cancer cells.
Tuesday, September 22, 2015
Personalized Heart Models For Surgical Planning
System can convert MRI scans into 3D-printed, physical models in a few hours.
Friday, September 18, 2015
Learning About Human Health Using Sewage
PhD student Mariana Matus studies human waste to understand individual and community health.
Thursday, September 17, 2015
Intensity of Desert Storms May Affect Ocean Phytoplankton
MIT study finds phytoplankton are extremely sensitive to changing levels of desert dust.
Tuesday, September 01, 2015
Searching Big Data Faster
Theoretical analysis could expand applications of accelerated searching in biology, other fields.
Thursday, August 27, 2015
Protein Found to Play a Key Role in Blocking Pathogen Survival
Calprotectin fends off microbial invaders by limiting access to iron, an important nutrient.
Wednesday, August 26, 2015
A Metabolic Master Switch Underlying Human Obesity
Researchers find pathway that controls metabolism by prompting fat cells to store or burn fat.
Friday, August 21, 2015
Capturing Cell Growth in 3-D
Spinout’s microfluidics device better models how cancer and other cells interact in the body.
Monday, August 17, 2015
Better Estimates of Worldwide Mercury Pollution
New findings show Asia produces twice as much mercury emissions as previously thought.
Thursday, August 13, 2015
Scientific News
Fixing Holes in the Heart Without Invasive Surgery
UV-light enabled catheter is a medical device which represents a major shift in how cardiac defects are repaired.
Chromosomal Chaos
Penn study forms basis for future precision medicine approaches for Sezary syndrome
Enzyme Malfunction May be Why Binge Drinking Can Lead to Alcoholism
A new study in mice shows that restoring the synthesis of a key brain chemical tied to inhibiting addictive behavior may help prevent alcohol cravings following binge drinking.
Key to Natural Detoxifier’s Reactivity Discovered
Results have implications for health, drug design and chemical synthesis.
New Treatment for Obesity Developed
Researchers at the University of Liverpool, working with a global healthcare company, have helped develop a new treatment for obesity.
New Protein Found in Immune Cells
Immunobiologists from the University of Freiburg discover Kidins220/ARMS in B cells and demonstrate its functions.
Will Brain Palpation Soon Be Possible?
Researchers have developed non-invasive brain imaging technique which provides the same information as physical palpation.
Shaking Up the Foundations of Epigenetics
Researchers at the Centre for Genomic Regulation (CRG) and the University of Barcelona (UB) published a study that challenges some of the current beliefs about epigenetics.
Groundbreaking Computer Program Diagnoses Cancer in Two Days
Researchers have combined genetics with computer science and created a new diagnostic technology can with 85 per cent certainty identify the source of the disease and thus target treatment and, ultimately, improve the prognosis for the patient.
Michigan Researchers Use Raman Spectroscopy
inVia confocal Raman microscope used in the study of various childhood diseases.
Scroll Up
Scroll Down
Skyscraper Banner

Skyscraper Banner
Go to LabTube
Go to eposters
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,600+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
3,800+ scientific videos