Researchers from science institute Riken and the University of Tokyo have succeeded in creating a polymer film that bends when exposed to light, providing hope for the development of new muscle-like devices and battery materials.
The research was conducted using azobenzene molecules, which are known to deform when irradiated. Azobenzene is an orange dye whose molecular structure changes and shrinks when exposed to ultraviolet light. It returns to its original state when visible light is applied. The shrinkage is minute — about four-ten millionths of a millimeter.
Takanori Fukushima, a team leader at the Riken Advanced Science Institute, and the other researchers created a structure called a “polymer brush” using a “hair” with three azobenzene molecules. This brush had a diameter of one-fifty thousandth of a millimeter and a length of one-ten thousandth of a millimeter. Polymer brushes were then aligned and processed into a film, and when light was applied to this new material, the material was found to bend.
University of Tokyo graduate student Nobuhiko Hosono discovered by accident that sandwiching polymer brush powder between two fluoropolymer sheets and hot-pressing them together aligned the brushes neatly, and this led to the creation of the new material.
The bending process resembles the function of muscles of living organisms, in which countless structural changes on the molecular level combine to produce one large movement. It is also hoped that the technology can be applied to produce a material dramatically increasing the generating efficiency of solar batteries.
