May 10, 2014 4:24 PM GMT
Materials that heal themselves are going bigtime. Scientists have cooked up a chemical concoction that can patch a 9-millimeter-wide hole in a sheet of plastic, a self-repair orders of magnitude larger than ever demonstrated before. The finding could lead to new kinds of airplane wings and spacecraft components that can repair themselves midflight.
“It’s exciting; I think it’s a big step forward in being able to autonomously heal structures without intervention,” says University of Michigan, Ann Arbor, mechanical engineer Ellen Arruda. She calls the researchers’ scheme “the polymer equivalent of a blood clot.”
Complex life could never have evolved without the ability to heal itself. When an animal suffers a puncture wound, for example, compounds flow from blood vessels to the wound site, where they feed the growth of new tissue to fill the damaged area. The process, however, requires a vascular system to deliver the needed components. Because most nonliving materials lack this complexity, repair typically requires human intervention.
Recently, though, scientists and engineers have begun designing materials that can patch up small defects. In one such scheme, narrow channels similar to animal blood vessels deliver compounds that seal small fissures in a material made of fiberglass and polymer resins. So far, such systems have only repaired fractures so small that opposite sides of the wound nearly touch. When the damage site is larger—say, the size of a bullet hole—liquid compounds tend to leak out before they can form a seal.