Crab inspired self-healing car coating could repair scratches

March 13th, 2009 - 11:28 am ICT by ANI  

London, Mar 13 (ANI): Direct sunlight might be bad for you, but it can do wonders to your car. Scientists have developed a new polyurethane material that heals its own scratches in less than an hour when exposed to sunlight.

The materials secret lies in using molecules made from chitosan, which is derived from the shells of crabs and other crustaceans.

Tiny scratches to the surface of the material close up in only a few minutes when the material is exposed to the ultraviolet light in sunlight.

The life-like healing occurs due to the damaged polymer molecules around the edges of a scratch use the energy from the UV to form new cross-links and recreate the network that makes up the material.

The work by University of Southern Mississippi researchers is reported in the journal Science.

According to Marek Urban, a polymer scientist at the University of Southern Mississippi, Hattiesburg, who led the study, the material could make a good topcoat for an automobile.

To make the development, Urban and his team combined polyurethane with a molecule made up of chitosan, a carbohydrate found in the shells of crustaceans like crabs and lobsters.

The researchers then modified the chitosan slightly with the addition of the structures composed of four carbon atoms called oxetane rings.

It is the oxetane rings that give the material its ability to heal, says Urban. When a scratch is made, some of the rings are broken, leaving chemically reactive free ends.

UV light exposure creates reactive spots on sections of the chitosan molecules which then combine with the broken oxetane rings to form new chemical cross links that close up the damage. The process appears to begin at the bottom of a scratch, pulling it closed like a zipper.

Urban says that scratches about 10 micrometers wide and 50 deep heal over after 30 minutes of exposure to UV light.

According to the expert, the material could be useful for a number of applications, including vehicles and furniture, or electronic devices like cellphones.

“Anything you can think of,” he told New Scientist, “If you scratch it, let it sit in Sun for some time and it’’s cured.” (ANI)

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