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Coating that repairs itself in the sun

Coating that repairs itself in the sun

According to an article published in BBCNews, scientists have created a coating that, when scratched, repairs itself with exposure to sunlight. When a scratch occurs, ultraviolet light triggers a chemical reaction that patches the damage.

The work, conducted by researchers at the University of Southern Mississippi, has been published in the journal Science.

The researchers designed the molecules by combining ring-shaped molecules called oxetane with chitosan.

The custom-made molecules were added to a standard blend of polyurethane, a popular varnish material that is also used in other products, from textiles to swimwear.

Scratches or other damage to the polyurethane coating breaks the oxetane rings, leaving loose ends that are highly prone to chemically reacting.

In ultraviolet light from the sun, the chitosan molecules split in two, adding to the reactive ends of oxetane.

Professor Marek Urban, director of the university's school of high-performance polymers and materials, and graduate student Biswajit Ghosh, observed that their coatings were able to completely self-repair in just 30 minutes.

Several self-healing compounds have been developed in recent years, but many of them rely on the inclusion of capsules or hollow fibers filled with materials that act as glue. When a scratch occurs, the capsules or fibers containing the glue break and the glue repairs the damage.

According to Professor Urban, these approaches are quite elaborate and often not economically feasible.

The new approach, by contrast, only requires adding a tiny number of repair molecules to the mix.

"There is still a lot of work to do, but we are on the right track," Urban said.

Source: BBC Science

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