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French chemists announced they had created rubber that heals itself after it has been cut, a breakthrough that could lead to clothes that self-mend if torn and toys that repair themselves if damaged by a tot.
The molecular concoction — described by other scientists as having "a touch of magic about it" — can self-heal at room temperature in around 15 minutes by simply pressing the damaged pieces together, they report in the British weekly science journal Nature.
Conventional rubber typically comprises long, cross-linked chains of polymers that can stretch and then recover to their original size and shape. The new formula made by a team at (1) France's National Centre for Scientific Research (CNRS) and a private firm, Arkema, achieves the same elasticity by using a mixture of two different kinds of smaller molecules.
Some are ditopic, which means they can hook up with two other molecules, and others are tritopic, meaning they can associate with three molecules. The network is meshed together by weaker hydrogen bonds, which get broken when the rubber is cut but also provide an atomic "glue," recombining into chains to bridge severed parts.
The ingredients comprise fatty acids made from ordinary vegetable oils, combined in a stepped process with diethyline triamine and urea, both cheap and common chemicals.
The result is a substance that at eight degrees Celsius (46 degrees Fahrenheit) becomes a translucent glassy plastic that, like soft rubber, can be strained five times its length before breaking.
"If you drill into a rubber sealing in a wall, the hole will repair by itself. Anything involved with compression, such as joints and rubberised coatings, can be fixed. The fracture and healing process can be repeated many times," said lead researcher Ludwik Leibler, of the CNRS' Soft Matter and Chemistry Laboratory.
Arkema and CNRS have already worked on other "self-healing" materials, including paint that smooths itself out if scratched, Arkema researcher Manuel Hidalgo said.
The first products from that research should be on the market "in a year or two," he told AFP. ■AFP
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