Shape-Shifting Plastic Powers Motors

A new polymer that changes shape and returns to its previous form, depending on the temperature could use ambient heat to drive tiny motors. The new shape-shifting polymer could be used as window blinds that open and close automatically without a battery or any other power source. Previous shape memory polymers lose their ability to “remember” their original shape after only a few cycles.

But the new polymer, designed by researchers from the Institute of Biomaterial Science at Germany’s Helmholtz Center, Geesthacht, is able to flip back and forth between two stages 250 times.Since they can change shape over and over, the polymers can drive motors. The Hemholtz center team demonstrated one, called a heat engine, in which a gear is turned as the temperature rises and falls. As the polymer mix is heated or cooled, some of the molecules inside crystallize and expand, while others start to flow and contract. That is what makes the movement and provides direction.

Using the polymer, the researchers demonstrated window blinds (photo above) that open when temperatures are warm and close when temps are cooler.

The work was published online in the July 8 issue of the Proceedings of the National Academy of Sciences.