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Saturday, 14 September 2013

Scientists create self-healing plastic








Scientists Create Self-Healing 'Terminator' Polymer

Scientists have made a materials breakthrough. They've created the first self-healing thermoset elastomer that requires no intervention to induce its repair. The findings could be huge when it comes to the creation of self-healing materials.

Self-healing polymers mend themselves by reforming broken cross-linking bonds. Yet this cross-linking healing mechanism usually requires an external stimulus, which means that these materials aren't necessarily practical. These stimuli can include energy inputs or specific environmental conditions, such as pH. The researchers came close before to making such a self-healing material. In Spain, scientists created self-healing silicone elastomers using silver nanoparticles. Unfortunately, an applied external pressure was needed to make them work.


Now, though, the researchers seem to have succeeded. In this new material, they have used an industrially familiar, permanently cross-linked poly(urea-urethan) elastomeric network. The new network has been shown to completely mend itself after being cut in two by a razor blade. It's the metathesis reaction of aromatic disulphides, which naturally exchange at room temperature, that causes this regeneration.

The new polymer has been dubbed a "terminator" polymer. It behaves as if it were alive, always healing itself when broken. Acting like a velcro-like sealant or adhesive, it displays a 97 percent healing efficiency and does not break when stretched manually.

"The introduction of a room temperature exchangeable covalent bond in class thermoset elastomers provides unique autonomous self-healing abilities without comprising the pristine material properties," said Richard Hoogenboom, head of the Supramolecular Chemistry group at Ghent University in Belgium, in a news release. "Close resemblance of this novel self-healing thermoset elastomer with current commercial materials makes it highly interesting for extending the lifetime of such materials."

There are practical applications for this new material, as well. In the future, it could be used to improve the security and duration of many plastic parts. It could potentially be employed in cars, houses, electrical components and biomaterials.

The findings are published in the journal Mater. Horiz. and Chemical Communications.