According to a study, beetle scales keep the secret on creating a durable paint from recycled plastic

Scientists at the University of Sheffield have discovered that the structure of the ultra-white beetle scales could be the key to making a bright white durable paint with the help of recycled plastic waste. .

The scales of Cyphochilus beetles are one of the brightest whites in nature and their ultra-white appearance is created by the nanostructure in their tiny scales, as opposed to the use of pigments or dyes.

Experts have now been able to recreate and improve this structure in the laboratory using inexpensive materials, thanks to a technique that could be used as a sustainable alternative to titanium dioxide in white paint.

Andrew Parnell, of the Department of Physics and Astronomy at the University of Sheffield, who led the research, said: "In the natural world, whiteness is usually created by a foamy structure similar to a cheese Swiss, consisting of a strong interconnected network and air.However, the structure and development of these structures and the evolution of their light scattering properties remained a mystery .

"After understanding these structures, we were able to take the plastic and structure it in the same way, ideally we could recycle the plastic waste that would normally be burned or sent to the landfill, structure it like the scale, then use them for white paint, which would allow painting with a much smaller carbon footprint and help meet the challenge of recycling single-use plastics. "

The results show that the foamy structure of beetle scales has the right proportion of voids, which optimizes the diffusion of light, thus creating an ultra-white coloration.

Conventional white paint contains nanoparticles of titanium dioxide, which strongly disperse light. However, the use of titanium dioxide is harmful for the environment because it contributes to nearly 75% of the carbon footprint of each paint box produced.

The researchers used a technique called X-ray tomography, similar to CT, but on a tiny scale. Scientists have used the X-ray imaging facilities of the ID16B instrument of the European Synchrotron Research Facility (ESRF) in Grenoble, France.

The intense X-ray source at the ESRF made it possible to measure intact whole scales, which was essential to understand them and to model the way they scatter light. To track how the synthetic material formed, they again used the ESRF to confirm the formation mechanism when the layer dried and structured.

Stephanie Burg, Ph.D. A researcher from the University of Sheffield said: "This research answers long-standing questions about how the structure within these scales is formed and we hope these lessons learned of nature will help illuminate the future of sustainable paint making. "

The team also used the Larmor instrument from the spallation neutron source ISIS, which measured the nanostructure of the synthetic whites they made. It was at the Rutherford Appleton Laboratory, in Oxfordshire, which is part of the Science and Technology Facilities Council.

The work was done in collaboration with the coatings company AkzoNobel, paint manufacturer Dulux. The paper Liquid-liquid phase separation morphologies at the scale of the ultra-white beetles and a synthetic equivalent were published today (29 August 2019) in Nature Communications Chemistry.

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