There is a new polymer that self-heals in a minute. There is already a polymer, made by Biswajit Ghosh and Marek W. Urban, that heals itself in an hour. It involves a a covalent element that splits apart and then reconnects under ultraviolet light in an hour.
But the new polymer is made by Mark Burnworth and his colleagues of rubbery oligomers with attached ligands. The healing relies on significant localized heating (caused by the chemical reactions in response to UV light) and on metal-ligand interactions. Two separate 30-second exposures to UV light repair the polymer.
This works because chromophoric reactions occur, which is to say that a specific light frequency causes them to heat up. This increased energy state depolymerizes the area around itself. Cooling re-establishes the polymer. Different wavelengths could be used for different damaged materials.
The Burnworth approach creates significant heat. For appliations where this is a problem, the cooler Ghosh and Urban method might be more appropriate, if slower, for healing to occur.
– A more thorough explanation with some diagrams is at: http://arstechnica.com/science/news/2011/04/new-elastic-polymer-self-heals-in-just-one-minute.ars
No comments:
Post a Comment