The first plastics capable of being deformed and temporarily fixed in a new shape by light illumination have been created, reported the latest issue of the journal Nature on Wednesday.

The achievement, published on the April 14 issue of Nature, will have potential applications in a variety of fields, said the researchers at Massachusetts Institute of Technology (MIT) and German GKSS research center.

"This is really a new family of materials that can change from one shape to another by having light shined on them," said Robert Langer, professor at MIT and co-author of the paper.

Key to the work is so-called "molecular switches," or photosensitive groups, that are grafted onto a permanent polymer network.

The resulting photosensitive polymer film is then stretched with an external stress, and illuminated with ultraviolet light of a certain wavelength. This prompts the molecular switches to crosslink, or bind one to another.

When the light is switched off and the external stress released, the crosslinks remain, maintaining an elongated structure. Exposure to light of another wavelength cleaves the new bonds, allowing the material to spring back to its original shape.

A variety of other temporary shapes can be produced in addition to elongated films, said the researcher.

"While the deformation is well-fixed for (the irradiated) layer, the other keeps its elasticity. As a result, one contracts much more than the other when the external stress is released, forming an arch or corkscrew spiral shape," said the authors.

The authors also said the temporary shapes are very stable for long times even when heated to 50 degrees C.

Currently, the researchers are developing medical and industrial applications using photosensitivity of the plastics.