Plastic that grows back after damage

Can you imagine a mangled car bumper that repairs itself within minutes of an accident? This can soon be a reality as researchers in the US have developed materials that not only heal but regenerate.

Until now, self-repairing materials could only bond tiny microscopic cracks.

The new regenerating materials fill in large cracks and holes by regrowing material.

The restorative material is delivered through two, isolated fluid streams (dyed red and blue).

The liquid immediately gels and later hardens, resulting in recovery of the entire damaged region.

"We have demonstrated repair of a non-living, synthetic materials system in a way that is reminiscent of repair-by-regrowth as seen in some living systems," said Jeffry S. Moore, a professor of chemistry at University of Illinois.

Such self-repair capabilities would be a boon not only for commercial goods but also for parts and products that are difficult to replace or repair, such as those used in aerospace applications.

The regenerating capabilities build on the team's previous work in developing vascular materials.

Using specially formulated fibres that disintegrate, the researchers can create materials with networks of capillaries inspired by biological circulatory systems.

"Vascular delivery lets us deliver a large volume of healing agents - which, in turn, enables restoration of large damage zones," said Nancy Sottos, a professor of materials science and engineering.

The vascular approach also enables multiple restorations if the material is damaged more than once.

The team demonstrated their regenerating system on the two biggest classes of commercial plastics: thermoplastics and thermosets.

They envision commercial plastics and polymers with vascular networks filled with regenerative agents ready to be deployed whenever damage occurs, much like biological healing.

The research appeared in the journal Science.