New materials: brilliant white without pigments
Polymer films that are extremely thin and characterized by a high light-scattering rate are produced by a new process developed by the Karlsruhe Institute of Technology (KIT). The inexpensive material may be applied industrially to various objects to give them an attractive white appearance. Moreover, the process can make products environmentally more compatible.
A brilliant white surface makes furniture and other objects appear clean, bright, and modern. So far, titanium dioxide has been the standard pigment used for white colouring of lacquers, paints, and plastics as well as of cosmetics, foods, chewing gum, or pills. However, the pigment is in the focus of criticism. «Titanium dioxide has a very high refractive index. It reflects incident light almost completely. But it is associated with the drawback that its particles do not degrade and thus pollute the environment in the long term,» says Professor Hendrik Hölscher of KIT’s Institute of Microstructure Technology (IMT). Besides, there have been concerns that titanium dioxide could be harmful to health.
«We avoid the use of pigments that are harmful to health and the environment by producing porous polymer structures of comparably high scattering efficiency,» Hölscher says. He and his team were inspired by the white beetle Cyphochilus insulanus, whose chitin scales appear white thanks to their special nanostructure. «Based on this model, we produce polymer-based solid, porous nanostructures, which resemble a sponge,» says Hölscher, who heads the Biomimetic Surfaces Group of IMT. Similar to the bubbles of shaving or bathing foam, the structure scatters light, which makes the material appear white. The new technology for low-cost and environmentally compatible white optics is suited for various surfaces.
KIT Center Materials in Technical and Life Sciences
D-76344 Eggenstein-Leopoldshafen, www.materials.kit.edu/index.php, www.sek.kit.edu/downloads/Datenblatt-IMT-bionische-Oberflaechen-en.PDF