Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

It Heals and Grows Together

12.01.2011
Polymer with amazing self-healing properties

Sooner or later, a cut to the skin or a broken bone will heal on its own; however, a scratch to a car’s paint or a tear in the wing of an airplane will not. Materials with self-healing properties could help extend the durability of products and make repairs easier.

Krzysztof Matyjaszewski and his co-workers at Carnegie Mellon University (Pittsburgh, USA) and Kyushu University (Japan) have now developed a polymer that can repair itself when irradiated with UV light—over and over again. As the scientists report in the journal Angewandte Chemie, this is the first material in which capped covalent bonds repeatedly reattach, even allowing fully separated pieces to be fused back together.

Some previous solid self-healing materials contain tiny capsules that tear open to release a chemical agent when the material is damaged and have been able to repair themselves only one time. Other materials, including some gels, can repair themselves repeatedly but lack the covalent bonds that increase materials strength and stability.

In contrast, the new polymeric material produced by the American and Japanese team is stable and repairs itself again and again. The secret to their success is that the polymer is cross-linked through trithiocarbonate units. These are carbon atoms bonded to three sulfur atoms, two of which use their second bonding position to attach to another carbon atom. These groups have a special property: they can restructure under UV light. The light breaks one carbon–sulfur bond in the trithiocarbonate groups. This produces two radicals—molecules with a free, unpaired electron. The radicals are very reactive and attack other trithiocarbonate groups to form new carbon–sulfur bonds while breaking others to form more free radicals. The chain reaction stops when two radicals react with each other.

The researchers were able to heal cut polymer fragments with irradiation—either immersed in liquid or in bulk. They only had to firmly press the cut edges together and irradiate them. The edges grew back together by means of the radical re-organization process described above.

The self-healing effect goes much further: even shredded polymer samples could simply be pressed together and irradiated to be fused into a continuous piece. The resulting object was in the shape of the cylindrical tube in which the procedure was carried out. This self-healing process can be carried out repeatedly on the same sample. The material is thus also interesting as a new recyclable product.

Author: Krzysztof Matyjaszewski, Carnegie Mellon University, Pittsburgh (USA), http://www.cmu.edu/maty/index.html

Title: Repeatable Photoinduced Self-Healing of Covalently Cross-Linked Polymers through Reshuffling of Trithiocarbonate Units

Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201003888

Krzysztof Matyjaszewski | GDCh
Further information:
http://pressroom.angewandte.org
http://www.cmu.edu/maty/index.html

More articles from Life Sciences:

nachricht New method to rapidly map the 'social networks' of proteins
27.06.2017 | Salk Institute

nachricht X-ray experiments reveal two different types of water
27.06.2017 | Deutsches Elektronen-Synchrotron DESY

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Collapse of the European ice sheet caused chaos

27.06.2017 | Earth Sciences

NASA sees quick development of Hurricane Dora

27.06.2017 | Earth Sciences

New method to rapidly map the 'social networks' of proteins

27.06.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>