Self-Repairing Car Paint: Just Add Sun

Author:  Dunia Rassy
Institution:  London School of Hygiene and Tropical Medicine

Visits to auto body shops might become obsolete after Marek Urban, a researcher from the University of Southern Mississippi, announced the development of a car paint that heals itself from scratches when exposed to sunlight. By adding a chemically modified version of chitosan, a crab shell component, to polyurethane, Urban's team obtained the remarkable coating. Their study was published in the March 13 issue of Science.

Polyurethane is widely employed in wheels, furniture, and surfboards due to its superior strength and lower density. Yet, it is still prone to mechanical damage. To address this, Urban combined chitosan, the carbohydrate that makes up the shells of shrimp, crabs, and lobsters, with polyurethane. The remarkable ability of chitosan to withstand scratches is rooted in its structure. The structure of chitosan includes a four-carbon ring called oxetane.

When the material is scratched, these rings break, providing free ends that can react with other molecules. At the same time, chitosan reacts with UV light and begins linking the free ends, mending the gap.

Urban envisions scratches that repair themselves while the vehicle is driven. Preliminary tests have revealed that it takes under an hour to repair the surface. Even though these tests were performed at a microscopic level, with scratches barely visible to the naked eye, the healing process could be used for wider scratches. The prediction arises as links begin forming at the bottom of the closest sides of the scratch. The only apparent drawback is that once the material repairs itself in a spot, it would not mend itself a second time in the same place.

The new material might make it to the market in the near future. In contrast to other self-repairing polymers, this one can be manufactured from readily-available materials and is easily synthesized. The fact that it relies on UV light, mainly provided by the sun, makes it a cheaper alternative. In an interview with Wired Urban showed his confidence in the future of the polymer: "This new material will have a lot of practical applications. It could coat anything that can be scratched,electronics, aircraft, cars, you name it."