Skin is spectacular stuff. Nick it with a razor or scrape it on the sidewalk, and it heals itself quickly. Synthetic materials are another story, although it’s not for lack of effort on the part of scientists.

Chemists have tried for years to develop self-healing polymer coatings for use on cars, furniture and other objects. Recent efforts use microspheres containing bonding chemicals. These tiny capsules are embedded in the coating. When a crack or scratch occurs, the spheres break and the chemicals flow into the void, patching it.

Image Credit... Chris Gash

Biswajit Ghosh and Marek W. Urban of the University of Southern Mississippi have come up with another approach, which they describe in a paper in Science. With their method, what breaks is not a sphere, but a ring-shaped chemical, oxetane, that is incorporated in the polyurethane polymer. Another compound in the polymer, chitosan, forms cross-links at the places where the oxetane breaks, healing the scratch.