Shape shifter
Scientists have created polymer rods that, even after being grossly deformed, will revert toward their original shape when exposed to ultraviolet (UV) light.
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Andreas Lendlein at GKSS Research Center in Teltow, Germany, and his colleagues bestowed this shape-memory property on a polymer blend by adding photosensitive molecules. When exposed to UV light of a certain wavelength, these molecules link, cinching the polymer’s own constituent chains in place. A dose of UV light of a different wavelength cleaves the bonds.
In a demonstration of the new material’s capabilities, the researchers twisted a rod-shaped sample into a spiral and exposed it to UV light, fixing the shape. When they subsequently exposed the spiral to UV light of a different wavelength, the polymer and stretched out to almost its original form.
The material could find applications in minimally invasive surgery, the researchers suggest. A surgeon could thread a thin piece of plastic through a small incision and into a blocked blood vessel. A fiber-optic probe could activate the material with light, triggering the polymer to spring into a shape that would keep open the vessel.
The researchers describe their new material in the April 14 Nature.