A new class of rubber-like material not only self-stretches upon cooling, but reverts to its original shape when heated, all without physical manipulation.
The material is like a shape-memory polymer because it can be switched between two different shapes. "However, unlike other shape-memory polymers, the material does not need to be programmed each cycle—it repeatedly switches shapes, with no external forces, simply upon cooling and heating," said Mitchell Anthamatten, an associate professor of chemical engineering at the University of Rochester.
Conventional shape-memory polymers need to be reprogrammed after each cycle, but that's not the case with the material developed by Anthamatten and his team. After multiple cycles of cooling and heating, they found that the material assumed its programmed shape and returned to its initial state with no noticeable deviation.
Possible applications are areas in which reversible shape-changes are needed during operations, including biotechnology, artificial muscles and robotics.