At the American Chemical Society’s National Meeting & Exposition this week in San Diego, researchers described a novel type of plastic that has a property of human skin. The plastics can heal scratches and cuts so they may be useful as self-repairing materials on cell phones, laptops, cars, and other consumer products. The plastics change color when scratched or cut and then fix themselves when exposed to light.
According to an ACS press release:
‘Mother Nature has endowed all kinds of biological systems with the ability to repair themselves,’ explained Professor Marek W. Urban, Ph.D., who reported on the research. ‘Some we can see, like the skin healing and new bark forming in cuts on a tree trunk. Some are invisible, but help keep us alive and healthy, like the self-repair system that DNA uses to fix genetic damage to genes. Our new plastic tries to mimic nature, issuing a red signal when damaged and then renewing itself when exposed to visible light, temperature or pH changes.’
Urban is at the University of Southern Mississippi in Hattiesburg and described his work at a press conference at the ACS meeting on Monday, March 26. He envisions a variety of applications for this new kind of highlight-and-fix plastic. For example, scratches on a car fender could be repaired by simply exposing the damaged area to light. On airplanes, the plastic can change color to warn engineers if an important machine part is damaged.
This new class of plastic is designed to overcome a critical flaw of plastics: Once damaged, plastics are very hard to fix and often just have to be replaced. For this reason, self-repair plastics have been one active area of research in materials science.
The plastics created by Urban’s group have small molecular links that stretch across the long chemical chains that make up the plastic. When a scratch or cut happens, these links break and change their shape. The shape change generates a visible color change as a red patch around the defect. When the damaged plastic is exposed to sunlight or light from a light bulb, pH changes or temperature, the molecular links connect up again, fix the damage, and remove the red mark.
Urban says the new class of plastics can self-repair repeatedly. He adds that the new plastics are also more environmentally friendly than most other plastics because its production is based in water rather than organic solvents. The Urban team now focusing on making self-repair plastics that can tolerate heat.
Source: “New plastics ‘bleed’ when cut or scratched — and then heal like human skin,” American Chemical Society, 03/26/12
Source: “New plastics ‘bleed’ when cut or scratched — and then heal like human skin,” ACS_Live UStream (video)
Image by donielle used under the Creative Commons license
Rajendrani "Raj" Mukhopadhyay is a science writer and editor who contributes news stories and feature articles on scientific advances to a variety of magazines. Raj holds Ph.D. in biophysics from Johns Hopkins University.