13 March 2009 University of Southern Mississippi, Hattiesburg
Self-repairing Nano Coating is up to Scratch
As good as new: Car scratches could soon heal themselves thanks to a revolutionary coating
Motorists may never have to worry about scratching their paintwork again.
Scientists claim to have invented a 'self-healing' coating that repairs scuffs or blemishes on paint when exposed to sunlight.
It apparently takes 15 to 30 minutes for scratches to melt away, and a car's paintwork could be restored to the condition it was in when it left the showroom.
In fact, the self-healing material's creators believe it could be used on any objects vulnerable to scratches – including compact discs, sunglasses, iPod screens, handbags, shoes and even furniture.
Although the material is still at the laboratory stage, it could be available on commercial products within five years, experts say.
Dr Marek Urban who developed the intelligent polymer at the University of Southern Mississippi , Hattiesburg , said it could also be used in medical tools where scratches can harbour germs.
'There are an immense number of opportunities for this,' he said. 'Basically anything externally exposed.'
Self-repairing materials have been the dream of engineers for centuries. Many have been inspired by human skin and tissue which meshes itself together if it is damaged.
Some materials include networks of tunnels or tiny nanoparticles that 'bleed' when broken, filling in gaps caused by scratches.
However, most of the existing products are complicated and expensive. The self-healing material, described today in the academic journal Science, is far cheaper and simpler.
The coating is a polyurethane – a material used in plastics, foams and films – containing chitosan, a chemical produced in the shells of crabs, lobsters and shrimps, and organic compounds called oxetanes arranged in rings.
When the coating is scratched, the rings of oxetane are broken to expose chemically reactive sites.
Ultraviolet light splits open the chitosan molecules exposing another set of reactive sites. The oxetane and chitosan attract each other, bond and close the scratches.
The material could be used to make car paint, or transparent plastic coatings for screens, glasses or watch faces. The cost 'is not really that great', Dr Urban added.
The speed of the repair depends on the sunshine. In Mediterranean weather scratches vanish three or four times quicker than they would in typical British weather.
'Dry or humid climate conditions will not affect the repair process,' Dr Urban writes in the journal Science. However, the coating only works once.
A scratch in exactly the same area would not repair itself. The material also needs more testing before it can be used in paints and protective coatings, he added.
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