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Aug 06, 2023

Butterflies Inspire Paint Without Pigments

The bright colors in most paints come from pigments. But over time these paints

The bright colors in most paints come from pigments. But over time these paints often lose their color, and some pigments can be toxic in certain applications. Now, researchers have developed a method to create paint colors without using any pigments and it's inspired by the same science that gives butterfly wings their bright hues.

The blue color in butterfly wings is not a blue pigment, but reflections of blue light. The same ... [+] physics inspired structural paint. (Photo by Peter Travers/Digital Camera Magazine/Future via Getty Images)

If light falls on an object, either from the sun or from artificial light, it tends to absorb some of the light and reflect the rest of it. If all light is absorbed, the object looks black. If everything is reflected, it's white (or the color of the original light source). But when we see an object in color, that often means that only certain wavelengths were reflected. Pigments in paints are each specifically tailored to capture certain wavelengths only, and the remaining reflected light determines the colors you see. That's how color works when you look at your walls, clothes, books, plants, or your pet's fur. But there is another way to create color.

Some colors in nature, such as butterfly wings, have distinct colors not solely because of the light they absorb, but mainly because they reflect specific wavelengths. Instead of pigments, the color you see is caused by detailed arrangements of reflecting structural features in the wings.

Inspired by the butterfly wings, the research group of Debashis Chanda at the NanoScience Technology Center of the University of Central Florida (UCF) developed a method to create paints that also use light reflection from small structures to generate their colors.

Unlike conventional pigment-based paints, these structural paints do not fade after they’ve been exposed to too much sun. "Normal color fades because pigment loses its ability to absorb photons," Chanda told UCF. "Here, we’re not limited by that phenomenon. Once we paint something with structural color, it should stay for centuries."

Other benefits of structural paint are that it is lightweight, so that you don't need as much paint to cover a surface. It also absorbs less heat than conventional paint, which means that it keeps surfaces cooler and could be used to reduce the cost and energy of air conditioning in summer.

But to test these benefits at a larger scale, the paint would need to be created in bigger facilities than a university research lab.

"At this moment, unless we go through the scale-up process, it is still expensive to produce at an academic lab." Chanda says. So the next step for him is to learn more about the unique aspects of the paint. "We need to bring something different like, non-toxicity, cooling effect, ultralight weight, to the table that other conventional paints can't."

This is not the first time researchers have developed paint based on the physics of butterfly wings. Lexus launched a similar type of paint, Lexus Structural Blue, in 2017. However, car lovers noticed that it could be challenging to repair even the smallest scratch with this unusual paint, so that's perhaps another thing to consider with any new type of structural paints as well.