Despite its many advantages, plastic can be difficult to fix, since even minor fractures can compromise its strength. But what if plastic could heal itself? Nancy Sottos and her team at the University of Illinois at Urbana-Champaign have developed composites that can repair themselves.

An early self-healing plastic developed by the team had microcapsules embedded throughout it. When a crack occurred, the capsules would burst, releasing resin and a catalyst to fill the crack.

According to Popular Science: "For things made entirely of composites, like car bumpers or airplane wings, microcapsules won’t cut it. Once the capsules are spent, no more healing can occur there. One of Sottos’ newest composites is laced with channels that can deliver the self-healing agent to fill cracks again and again. The material was able to heal the same spot 30 times in the lab. But Sottos says it could be 20 years before it’s reliable enough for safety-critical applications (i.e., we’ll have self-healing bumpers long before self-healing airplanes).

Materials in extreme environments require even more ingenuity. Instead of relying on an onboard catalyst, engineer Melik Demirel of Pennsylvania State University created a polymer whose healing reaction is triggered by water, along with heat and pressure. Its proteins mimic those of squid teeth, which heal themselves by reconnecting broken hydrogen bonds."

To learn more, read "This Plastic Can Repair Itself" from Popular Science.