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Critter Chemistry

February 24, 2003

From Butterflies to New Materials

The striking colors of butterfly wings, like those shown, come from light diffracting off the ordered microstructure of their scales. The biological nanostructure also benefits the butterfly by shedding water and dirt. Researchers in Japan have now made materials that mimic these properties of butterfly wings [Angew. Chem. Int. Ed., 42, 894 (2003)]. Chemistry professor Osamu Sato at Kanagawa Academy of Science & Technology and coworkers prepared "inverse opal" films from polystyrene spheres several hundred micrometers in diameter and silica nanoparticles 6 nm in diameter. The mixture self-assembles into a regular hexagonal array with the smaller silica particles filling in the gaps between the closely packed polystyrene spheres. Burning off the polystyrene leaves an ordered array of holes that appears brilliant blue, green, or red, depending on the size of the original spheres. The hydrophobicity of the films is enhanced by treating them with a fluoroalkylsilane. The films could form the basis of self-cleaning decorative materials, the authors suggest.

Chemical & Engineering News
ISSN 0009-2347
Copyright © 2010 American Chemical Society