Materials that repair their own defects

Materials that repair their own defects

According to an article published this month in Technology Review, new protective coatings developed at the University of Illinois repair their own scratches without any outside intervention, protecting the metal they cover. These coatings, marketed by Autonomic Materials of Champaign, Illinois, could be on the market in as little as four months.

The materials, described online this week in the journal Advanced Materials, were developed by Paul Braun and Scott White, both professors at the Beckman Institute at the University of Illinois, Urbana-Champaign. The self-healing system consists of two kinds of microcapsules: one filled with polymer building blocks and the other with a catalyst. Because the capsules, made of polyurethane, keep reactive chemicals isolated inside, they can be mixed into a wide range of coatings. When the coatings are damaged, the microcapsules break and their contents flow into the scratches, forming siloxane, a polymer that Braun compares to bath putty. Unlike other self-healing systems, these coatings do not require high temperatures and humidity to fix.

The researchers scratched some steel plates, some coated with the material and others with a conventional coating; and then they were soaked in salt water for five days. The metal coated with the new material was protected from oxidation, while scratches from the conventional coating allowed significant oxidation.

Christopher Bielawski, assistant professor of engineering and materials science at the University of Texas, Austin, highlights the practicalities of these new coatings, made from cheaper and widely available chemicals. And Braun says the new additives could be used in a wide range of applications in coatings that repair at temperatures as low as 150ÂșC. The group demonstrated the operation of the self-repair system on various coatings, including commercialized paint from a military vessel.

Source: Technology Review

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