Understanding shape-shifting polymers
Shape-memory polymers are not a new discovery, as anyone who has played with Shrinky-Dinks or who has used heat-shrink tubing for wires in an electronic circuit can testify. But now, thanks to new analysis by researchers at MIT, the behavior of these interesting materials has been mathematically modeled in detail, which should make it easier to use the materials in new ways; potential applications include implantable biomedical devices and space structures that could be launched in a compact form and then unfurled once in orbit.Shape-memory materials share an unusual property: They can be squished, twisted or bent into a variety of configurations, but when heated above some threshold temperature (for example, by being dunked in warm water or heated in an oven) they revert to the original shape in which they were made. Metal alloys such as nitinol (an alloy of nickel and titanium) were the first such materials studied,...