Body temperature reactive polymer created

A polymer that changes shape due to body heat has been created by a team of US scientists.

The material – a type of shape memory polymer – is programmed to retain a temporary shape until activated by heat and then returns back to its original form.

Professor Mitch Anthamateen, from the University of Rochester in New York, said: “Tuning the trigger temperature is only one part of the story. We also engineered these materials to store large amount of elastic energy, enabling them to perform more mechanical work during their shape recovery"

Understanding how to control crystallisation when the polymer was cooled or stretched was the first step to creating the polymer. Crystallites – small segments of the polymer that align in the same direction when the polymer chain is stretched – are formed when the material is deformed. As this happens it is harder for the polymer to revert back to its original state meaning the polymer becomes stable.

The scientists used molecular linkers to connect the individual polymer strands, and altering the number and types of linkers used allows the trigger temperature to be tuned.

Professor Anthamatten said: “Our shape-memory polymer is like a rubber band that can lock itself into a new shape when stretched. But a simple touch causes it to recoil back to its original shape."

The polymer can be optimised to store as much elastic energy as possible meaning it can lift an object one thousand times its weight. Sutures, artificial skin, body heat assisted medical dispensers and self-fitting apparel are some examples of what the polymer could be used for.

The findings were published in Journal of Polymer Science Part B: Polymer Physics.