At room temperature, for instance, a plastic tube might have a diameter of 4.5 millimeters. Heat it to 40 degrees Celsius and it might go 6.8 centimeters. Heat it again to 60 Celsius and it might contract to a size between the two other diameters. You could also get plastic sheets that form shapes at one elevated temperature and then anchor themselves at a higher temp. The acrobatics in the photo are the result of different temperature levels.
Someday, these plastics could be used to make stents and other medical devices, or really in all sorts of products where you would want to manipulate the material but can't get at it.
The invention in part came out of a lab at MIT directed by Robert Langer, one of the university's more prolific inventors.