Self healing

Scientists develop a plastic that can repair itself when heated

Last Updated: Saturday 04 July 2015

-- (Credit: Kumar)imagine a window pane repairing its own cracks! No, this is not science fiction. It can actually happen as has been shown recently by a team of scientists, who have developed a plastic which can heal itself when heated and cooled. Plastics that can heal themselves are not new. They have been used in specialised applications for long. Some of them for instance, form polymer chains to bridge over a crack while others release a glue-like substance to close the crack. None of these, however, can be used if the material gets cracked repeatedly.

F Wudl and his colleagues from the Los Angeles-based University of California have developed a plastic that consists of tiny Velcro like strips. The Velcro like links are actually chemical bonds some of which break when the material is heated. When the material is heated to about 120C, the strips can be pulled apart. This is because at higher temperature, the molecules get enough energy to break the bonds. They form several bonds that give rise to a dense cross-linked network.

When the cracked material is heated, the sticky ends of the molecules that can form the bonds are exposed. These can then combine with one another to form dense networks of bonds that can close over the crack. A thin piece of plastic can be cracked and fixed several times. Though every time a crack is mended the fixed material is less tough than the original one, the material behaves better than other self-healing plastics like thermoplastics.

Scientists feel that plastics of this kind can find extensive use in protecting sensitive equipment like silicon chips apart from being used for more mundane applications like self-repairing windows or displays.

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