|Broken polymer chains reform to repair a crack in a polymer material when it is pressed together and exposed to UV light.(Photo by Krzysztof Matyjaszewski, Carnegie Mellon University)|
A new polymer material that can repeatedly heal itself at room temperature when exposed to ultraviolet light could eventually lead to the development of self-mending medical implants. Created by researchers at Carnegie Mellon University (CMU; Pittsburgh) and Kyushu University (Fukuoka, Japan), the polymer heals itself when a crack is pressed together and exposed to UV light.
As reported in MIT's Technology Review, separate pieces of the material can be fused together to form a single solid piece. That same piece can also be cut into pieces and reassembled at least five times. And with further refinement, the material could mend itself many more times, remarks CMU chemistry professor Krzysztof Matyjaszewski, the research team's leader.
The new polymer contains carbon-sulfur bonds that promote the self-healing process. "There are thousands of chemical bonds here, and even if you lose a small percent, one can think about potentially repeating the healing a hundred times," Matyjaszewski comments.
The quest for self-repairing polymers has already led scientists to develop materials that heal when exposed to heat or certain chemicals. But because the CMU team's polymer operates at room temperature, is easy to acquire and handle, can target specific areas for repair, and is a noncontact material, it is superior to self-repairing materials requiring heat or chemicals. However, the new material has two drawbacks: it requires pressure, and the repair process takes hours.
Despite its limitations, Matyjaszewski stands by the novel polymer. "You can make materials that are harder or softer," he says. "Every self-healing material is somehow unique and has advantages over the other ones. It depends on the properties and area of application.