Netherlands. Drawing inspiration from birds, beetles and butterflies, researcher Jessica Clough of Wageningen University's division of Physical Chemistry and Soft Matter developed a painting that does not lose its coloration regardless of its exposure to the elements.
Colors are usually created by pigments that absorb certain parts of light and reflect others. We only see the light being reflected. However, when light is absorbed, a chemical reaction also occurs that breaks down the pigment.
The scientist says it was discovered that in butterfly wings and peacock feathers, any light that is not reflected passes directly through it instead of being absorbed. This creates a "photonic color," which retains its intensity for a long time: "Some insect fossils are as colorful as they were millions of years ago," he notes.
This finding was published in the scientific journal Advanced Optical Materials, where it is also revealed that the researchers managed to reproduce these nanostructures of the animal kingdom in the laboratory by stacking small plastic beads. Between the beads, they put silica, and when heated, the plastic beads disappear and the silica hardens, creating a structure with air bags where the beads used to be. The size of the beads determines the color: blue for the smaller beads, then green and purple for the larger beads.
To prove that painting works, Jessica Clough made a painting (see photo) based on the work of Vincent van Gogh. "This paint maintains its color and contains no toxic pigments, which makes it harmless to humans," Clough explains.
At the moment, the range of colors is limited. "Blue and green work well," Clough says, "but structures that reflect red also reflect blue, which creates purple." In nature there are also no red photonic colors. For example, red feathers on parrots are the result of a chemical color. In the future, the researchers hope to remedy this with a mix of small and large beads that don't reflect blue.
Source: Resource WUR.
