THE anger that most people feel when they discover a scratch on their vehicles often turns to rage when they see the body-shop repair bills. Those hard feelings might be avoidable someday, thanks to a team of researchers who say theyve created a type of paint that can heal itself when exposed to ultraviolet light. The idea improves on other experimental coatings that repaired themselves when exposed to heat, said Stuart Rowan, a polymer chemist at Case Western Reserve University in Cleveland. Rowan is among a team of materials scientists who designed and tested the new material. We thought it would be cool if you just shine light on it, Rowan said. A paper on the research is published today in the journal Nature. The materials were created by a mechanism called supramolecular assembly. Unlike conventional polymers, which consist of long, chainlike molecules with thousands of atoms, these materials are composed of smaller molecules, which are assembled into chains that use metal atoms as a molecular glue. The result is new materials called metallo-supramolecular polymers. When hit with intense ultraviolet light, they detach from the metal and form a liquid. When the light is switched off, the materials reassemble and solidify again to restore the original properties. Voila The scratch is gone. Normal sunlight doesnt contain enough ultraviolet to trigger the reaction, Rowan said. Ultraviolet pen lights and black lights, however, do. Rowan said the polymer could be used in varnishes for flooring and furniture, and in scratch-resistant coatings for eyeglasses. Terrence Jones, manager at Buckeye Collision and Glass on the Far East Side, said the cost of a paint job can range from a few hundred dollars to more than a thousand. If someone has invented that, Id love to see it, Jones said of self-healing paint. But dont expect to see it soon in stores. Rowan and Christoph Weder, a collaborator and polymer chemist at the University of Fribourg in Switzerland, said a lot of work is needed before the compound can be mass-produced and withstand normal wear and tear. I personally think we can find cheaper, easier-to-access variants of this material, Rowan said. Weder said this idea has legs. Weve developed tools that developers of commercial materials can use, Weder wrote in an email. The hardness of our materials needs to be significantly increased to be useful for automotive coatings. DP