Beetle inspires ultra-white coating
You may think that a sheet of plain paper is already pretty white, but scientists from the University of Cambridge have created an eco-friendly material that's reportedly 20 times whiter. In order to do so, they copied the scales of a Southeast Asian beetle.
Ordinarily, bright colors are produced using pigments that absorb some wavelengths of light while reflecting others. To produce the color white, though, all wavelengths need to be reflected at the same efficiency. In man-made items, this is typically achieved by incorporating highly refractive particles of pigments such as titanium dioxide or zinc oxide.
That's where the Cyphochilus beetle comes in. Its scales get their white coloration not from pigment, but from a light-scattering network of the naturally-occurring molecule chitin.
Working with colleagues from Finland's Aalto University, the Cambridge team was able to copy the structure of that network in the form of flexible membranes composed of carefully-arranged cellulose nanofibrils (tiny strands). Not only is cellulose cheap, plentiful and non-toxic, but unlike titanium dioxide and zinc oxide, it's also fully sustainable and biocompatible.
Because they scatter light and produce the color white so effectively, the membranes are able to be ultra-thin – just a few millionths of a meter thick. According to the researchers, once the production process is optimized, they could likely be even thinner. It is hoped that the technology could ultimately be applied to things like paints, cosmetics and even foods.
A paper on the research was recently published in the journal Advanced Materials.
Source: University of Cambridge