What's the News: Researchers have developed the fastest yet self-healing polymer: The new class of materials dubbed "metallo-supramolecular polymers" heal after only one minute under UV light even when they're repeatedly cut. This could eventually lead to self-repairing floor varnishes, automotive paints, and other applications. University of Illinois at Urbana researchers Nancy Sottos and Jeffrey Moore say these these healable polymers "offer an alternative to the damage-and-discard cycle" that is rampant in our consumer society, and could pave the way for products "that have much greater lifespans than currently available materials." (You can see the process below in a press video from Case-Western Reserve University.) http://www.youtube.com/watch?v=h-fka0wfY8w How the Heck:
Unlike most polymers, which are composed of long molecular chains, metallo-supramolecular polymers are made of "short chains that are glued together with metal ions."
Scratches break up the polymer chains of metallo-supramolecular polymers. By shining intense UV light on and near the scratch, the metal ions heat to over 220°C in 30 seconds, depolymerizing the material.
While still depolymerized, the unglued particles act like a liquid and flow together again, smoothing out scratches in the process.
And when the intense UV light is removed, the metal quickly cools, and the now-smooth surface solidifies in seconds.
The polymer is made up from many bonded molecules of a complicated macromonomer custom designed to separate under the proper conditions.
What's the Context:
Most self-healing polymers depolymerize via heat, which makes the self-repairing process difficult because it's hard to isolate heat to a specific (and small) area. According to University of Fribourg, Switzerland, polymer chemist Christoph Weder, "By using light, we have more control over the process … since light can be applied very locally, that is, only in the vicinity of a defect. This leaves the other portions of an object untouched, so it can continue to serve its function while the damaged portion is healed."
In 2009, other researchers developed a polymeric material that self-repaired in about one hour, but instead of relying on the quick depolymerizing characteristics of metal, this old research relied on chemical bonding between organic compounds.
Other scientists have worked on getting airplanes to heal themselves.
And don't forget the self-healing rubber made from vegetable oil and a pee ingredient.
Not So Fast: Don't expect to purchase a self-healing car anytime soon. "What we have reported is not something that I expect to be commercialized tomorrow or next year," Weder told MSNBC. "It's really a first generation of a class of materials that need further refinement." The Future Holds: The present study healed cars using only intense ultraviolet light; now they're looking into whether other light wavelengths are more effective. Reference: Mark Burnworth, Liming Tang, Justin R. Kumpfer, Andrew J. Duncan, Frederick L. Beyer, Gina L. Fiore, Stuart J. Rowan & Christoph Weder. "Optically healable supramolecular polymers." Nature. doi:10.1038/nature09963
