It heals and grows together: Polymer with amazing self-healing properties
(PhysOrg.com) -- 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 carbonsulfur 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 carbonsulfur 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 irradiationeither 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.
More information: Krzysztof Matyjaszewski, Repeatable Photoinduced Self-Healing of Covalently Cross-Linked Polymers through Reshuffling of Trithiocarbonate Units,
Angewandte Chemie International Edition, http://dx.doi.org/ … ie.201003888
Provided by
Wiley
-
From lemons to lemonade: Reaction uses carbon dioxide to make carbon-based semiconductor,
28 comments
-
Thioridazine kills cancer stem cells in human while avoiding toxic side-effects of conventional cancer treatments,
3 comments
-
SpaceX private rocket blasts off for space station (Update),
41 comments
-
Climate scientists say they have solved riddle of rising sea,
30 comments
-
Scotland passes turbine test to harness tidal power,
40 comments
-
Force in a magnetic coupling
7 hours ago
-
Sign of scalar product in electric potential integral?
14 hours ago
-
Heat engines: how can we yield work?
15 hours ago
-
Work done by us on the spring
May 25, 2012
-
Surface current density
May 25, 2012
-
Work done on body moving in a circle
May 25, 2012
- More from Physics Forums - Classical Physics
More news stories
High-speed method to aid search for solar energy storage catalysts
Eons ago, nature solved the problem of converting solar energy to fuels by inventing the process of photosynthesis.
22 hours ago |
5 / 5 (3) |
3
|
From lemons to lemonade: Reaction uses carbon dioxide to make carbon-based semiconductor
(Phys.org) -- A materials scientist at Michigan Technological University has discovered a chemical reaction that not only eats up the greenhouse gas carbon dioxide, it also creates something useful. And, by ...
May 21, 2012 |
4.7 / 5 (88) |
28
|
New CO2-removing catalyst can take the heat
(Phys.org) -- The current method of removing the greenhouse gas carbon dioxide (CO2) from the flues of coal-fired power plants uses so much energy that no one bothers to use it. So says Roger Aines, principal ...
May 24, 2012 |
5 / 5 (7) |
7
|
Researchers demonstrate possible primitive mechanism of chemical info self-replication
(Phys.org) -- When scientists think about the replication of information in chemistry, they usually have in mind something akin to what happens in living organisms when DNA gets copied: a double-stranded molecule ...
May 25, 2012 |
5 / 5 (4) |
2
|
Castor oil: Action mechanism of one of the oldest drugs known to man elucidated
Castor oil is known primarily as an effective laxative; however, it was also used in ancient times with pregnant women to induce labour. Only now have scientists at the Max Planck Institute for Heart and Lung ...
May 21, 2012 |
3 / 5 (2) |
3
|
SpotterRF debuts Radar Backpack Kit (w/ Video)
(Phys.org) -- SpotterRF has announced a special radar backpack kit designed to enhance situational awareness for soldiers on the ground. The company says its special radar is designed for warfighters as part ...
Australia hails surprise super-telescope decision
Australia has hailed a surprise decision giving it a role in a radio telescope project aimed at revolutionising astronomy, vowing to draw on its decades of experience in space science.
Astronomers seize last chance in lifetime for Venus Transit
Astronomers are gearing for one the rarest events in the Solar System: an alignment of Earth, Venus and the Sun that will not be seen for another 105 years.
Thousands of shellfish found dead in Peru
Thousands of crustaceans were found dead off the coast of Lima following the mystery mass death of dolphins and pelicans, the Peruvian Navy said Friday.
SpaceX capsule has 'new car' smell, astronauts say
SpaceX's Dragon cargo vessel smells like a new car, said astronauts at the International Space Station after opening the hatches Saturday following the spacecraft's landmark mission to the orbiting lab.
Family history of Alzheimer's affects functional connectivity
(HealthDay) -- Cognitively normal individuals with a family history of late-onset Alzheimer's disease (AD) may display lower resting state functional connectivity in the default mode network (DMN) of the brain, ...
Jan 13, 2011
Rank: not rated yet
Jan 13, 2011
Rank: 1 / 5 (2)
I just hope this stuff ONLY reattaches to itself. Otherwise, I detect a nightmare brewing...
Jan 13, 2011
Rank: 1 / 5 (1)