Just over six years ago, we reported that Nissan had developed a "Scratch Guard Coat" paint designed to repair scratches on not only cars, but on painted surfaces in general. The company has already applied its paint technology to a number of Nissan and Infiniti models, and in 2009 it announced that it would license it for use on mobile phones. It appears there weren't many takers as Nissan has now announced that it has produced the world's first self-healing iPhone case that makes use of the Scratch Shield paint.

Nissan initially developed the Scratch Shield paint finish in collaboration with the University of Tokyo and Advanced Softmaterials Inc. for automotive use and it is currently available on the Nissan Murano, 370Z and X-Trail, along with Infiniti models. Although the Scratch Shield technology has been used in Japan where NTT DoCoMo has used it on its Style Series N-03B mobile phones, Nissan says the trial now underway with an initial batch of prototype iPhone cases marks the first time its self-healing paint finish has been trialed on a non-automotive product in Europe.

The Scratch Shield paint is made from polyrotaxane, which has a chemical structure that is able to react and change back to its original shape and fill the gap that results from a fine scratch. Small scratches can heal in as little as an hour, while more severe scratches can take up to a week. Aside from its self-healing properties, Nissan says the Scratch Shield paint also provides a surface that is more gel-like and easier to grip than the glossy surface produced by conventional paint.

Under the outer paintlayer, Nissan says it has also borrowed other automotive engineering technologies in developing the Nissan Scratch Shield iPhone case. This includes the use of ABS plastic, a high grade material widely used in the automotive industry that the company says enables a more rigid, robust and tighter-fitting case.

An initial batch of prototype Scratch Shield iPhone cases have been provided to selected journalists and customers for BETA testing and, if demand proves strong, Nissan plans to release the cases compatible with the iPhone 4 and 4S for sale to the public later this year.

Nissan's Scratch Shield isn't the only self-healing coating going around. Way back in 2001, researchers at the University of Illinois at Urbana-Champaign developed a self-healing coating that contained microcapsules that would rip open and fill the gap when scratched. Fraunhofer researchers followed up in 2009 with a similar approach for electroplated coatings that used nano-capsules. Also in 2009, scientists at the University of Southern Mississippi developed a polyurethane coating that used a derivative of chitin - the main component of the the exoskeleton of crustaceans - and healed when exposed to sunlight.

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