Researchers have developed advanced shape-memory polymers that could find uses as expandable stents and fasteners that close themselves. The researchers who developed self-tying sutures that change shape when exposed to light have now made morphing structures that can take on three consecutive shapes in response to changes in temperature. The shape-changing polymers could eventually be employed as removable stents and self-closing fasteners used in assembling complex parts. The structures are made of shape-memory polymers, a class of materials that change from one preset shape to another in response to a new condition, such as increased heat. In the past few...