A newly created material has the bizarre property

Jun 17, 2009 20:31 GMT  ·  By

Researchers at the University of California in Riverside (UCR) have managed to successfully design a mechanism that can help induce rapid color modifications to materials being subjected to a magnetic field. The microscopic polymer beads have the ability to shift their orientation according to the direction of the magnetic field, so each time it's moved, the colors change. The find could open up new avenues of research into creating things as rewritable color display units, or environmentally friendly color paints, the experts say.

The beads, scientifically known as magnetochromatic microspheres, are very stable, the team shares. They are able to withstand various dispersal mediums, including water, alcohol, hexane and even polymer solutions, which essentially means they maintain their ability to shift colors in a large variety of chemical mediums. The more environments they can survive, the wider the array of possible applications for the new material, the scientists explain.

“Unlike many conventional approaches, the instantaneous color change occurs with no change in the structure or intrinsic properties of the microspheres themselves. What changes instead are the magnetic fields acting externally on the orientation of these microspheres, these photonic crystals. Our work provides a new mechanism for inducing color change in materials. Now, for the first time, stable photonic materials with tunable colors can be fabricated on a large scale,” UCR Assistant Professor of Chemistry Yadong Yin says. He has been the leader of the research group comprised of researchers from the US and the Seoul National University (SNU), in South Korea.

“The new technology has a great potential for a wide range of photonic applications because the on/off switching of the diffraction color by the rotating photonic sphere is fast, greatly simplifying the pixel structures. Therefore, the new technology is suitable for very large-scale displays, such as active signage,” biophotonics and nanoengineering expert Sunghoon Kwo, from the SNU, adds. His lab has collaborated closely with the UCR team for the new study, which appears in the June 15th issue of the Journal of the American Chemical Society.

“Conventional methods to produce tunable structural color rely on changing the periodicity of the array or the refractive index of the materials – changes that are difficult to achieve or involve slow processes. In our method, the color is tuned by changing the relative orientation of the periodic arrays in the microspheres by conveniently using external fields. The use of magnetic fields as external stimuli has the additional benefits of instant action, contactless control and easy integration into electronic devices already in the market,” Yin concludes. Further details on the material can be found here.