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SCIENTISTS AT THE University of Illinois in the US have created a self-healing polymer coating which they say could be used for a wide range of purposes  from car paint to patio furniture.

The coating contains microcapsules less than 100 µm in diameter. Some capsules are filled with a catalyst, others with a healing agent, and incorporated into the coating medium, which could be just about any liquid coating material. If the coating is scratched, the capsules break open causing the catalyst and the healing agent to react, repairing the damage. This could take minutes or hours, depending on conditions.

The system was tested by scratching steel plates with a razor blade, some treated with the self-healing coating, others with just an ordinary coating. The samples were then left in a salt solution. Those with the self-healing coating had not corroded even after 120 hours, those without were extensively corroded after 24 hours.

“Our dual capsule healing system offers a general approach to self-healing coatings that operates across a broad spectrum of coating chemistries. The microcapsule motif also provides a delivery mechanism for corrosion inhibitors, antimicrobial agents, and other functional chemicals,” says Paul Braun, professor of materials science and engineering, who co-wrote the research paper.