Researchers managed to reproduce the effect of nature’s purest white color, having developed non-toxic material from cellulose nanofibrils.
The secret of Cyphochilus beetle has long deprived researchers of sleep: its white color is whiter than that of the sheet of the whitest paper. Thus, in 2007, Pete Vukusic, Optical Physicist at Exeter University (the UK), reported that the mystery of beetle is cracked…
Let’s first recall some facts about optics. Surfaces of various colors diffuse, absorb, and reflect light fluxes of different wavelengths. Thus, absolute black color able to absorb any light fluxes. Vantablack, the blackest ever developed material consisting of vertically aligned carbon nanotube arrays absorbs 99,965% of all the radiation in the visible spectrum. In theoretical terms, ideal mirrored surface may completely reflect all the radiation. However, the surface of ideal white color shall diffuse light the radiation of waves of any length exactly in the same way – but in this case our eyes will perceive it as white colored.
Having studied the scales of white beetles using electron microscopes, Mr. Vukusic concluded as follows: scales scatter light through a complex web of a biological structure called chitin. This structure is so tiny that microstructures of scales diffuse light nearly ideal. And now, a decade later, the team of researchers inspired by this creation of nature has developed material that works by the same principle.
As you may know, to paint a wall white you shall apply the paint in several layers. Olimpia Onelli, Lead Researcher of working group at University of Cambridge (the UK) said that it is sufficient to apply a layer of 10 μm thick of cellulose nanofibril membranes (ten times thinner than a human hair) to get a white color on any surface.
This material was developed by using a centrifuge, where cellulose was spun till the receipt of fibers of the proper width. Then these fibers were separated from the suspension and formed textured nanomaterial suitable to turn any surface into an ideal white – it is some 20 to 30 times whiter than the whitest paper. What matters is that this material is 100% eco-friendly – this is pure cellulose that may be applied to skin or even consumed with no damage to human health.