A new polymer material created by researchers at Carnegie Mellon University and Kyushu University that can repeatedly heal itself at room temperature when exposed to ultraviolet light presents the tantalizing possibility of products that can repair themselves when damaged.

Self-healing materials have been made before, mainly polymers and composites. But most of those have relied on tiny capsules that are filled with a healing agent. When the polymer cracks, the capsules break open and release the healing agent, which becomes polymer solid and seals the crack and restores the material’s properties. But once the capsules are depleted, the material can no longer mend itself.