Researchers have uncovered shape-memory properties in a commercially available polymer that is widely used to make fuel-cell membranes. The polymer, Nafion, can take on four different shapes in response to temperature changes, according to the [removed]findings[/removed] published in Nature.  Previously, researchers have made triple-shape polymers.

The polymers are being developed for self-adjusting orthodontic braces.

Shape-memory polymers go from a predefined shape to another in response to triggers such as temperature, light, or magnetic field. Most of these materials have one temporary shape and a permanent state they revert to when triggered.