Researchers have uncovered shape-memory properties in a commerciallyavailable polymer that is widely used to make fuel-cell membranes. Thepolymer, Nafion (pictured at left), can take on four different shapes in response totemperature 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 responseto triggers such as temperature, light, or magnetic field. Most of thesematerials have one temporary shape and a permanent state they revert towhen triggered.