When you hear the words "sustainable paint" you might think of one with no VOCs, but there's a new coating in town that promises to be even more eco-friendly. Like many great innovations, this new paint was discovered by accident. It was a mirror-making fail that structurally mimics naturally occurring colors found on animals. The scientists who created it say it's lighter and longer-lasting than traditional paint, and it offers a cooling effect.
Clearly, there are a lot of possible applications for such a product, which the creators call ultralight plasmonic structural color paint, whether or not you understand how it works. But let's try to shed some light on this new development.
Before diving into plasmonic paint, it may help to review how regular paint works and has worked for millennia.
To make paint, pigments like minerals, metals or chemicals are mixed with liquid, usually oil. It's the pigments that give paint its color, and they work by absorbing some light wavelengths and reflecting others. What gets reflected is what we see as color.
The problem with this tried-and-true method of making paint is that it may be made with toxic chemicals, is chemically unstable and can fade overtime. It also traps heat. Even white paint does not fully reflect sunlight.
A Happy Accident
A team of researchers at University of Central Florida (UCF) was working on making an aluminum mirror and noticed frustrating "clumps of aluminum atoms tiny enough to be invisible yet large enough to disrupt the mirror's shine," according to Wired.
Although it was bad news for their mirror project, they realized the tiny atoms oscillated in white light and reflected light. The size of the atoms determined which color they reflected.
That meant the researchers could generate different colors simply by using different sizes of aluminum particles. When the particles are attached to mirror and converted into color flakes, they can be mixed with liquid to create paint.
This type of color production is called "structural," and it is the way many species produce their color, according to researcher Debashis Chanda, a professor in UCF's NanoScience Technology Center.
"The range of colors and hues in the natural world [is] astonishing — from colorful flowers, birds and butterflies to underwater creatures like fish and cephalopods," Chanda said in the journal UCF Today. "Structural color serves as the primary color-generating mechanism in several extremely vivid species where geometrical arrangement of typically two colorless materials produces all colors. On the other hand, with man-made pigment, new molecules are needed for every color present."
"But nature has a very different way of creating color than we do," Chanda said. The colors displayed by butterflies, for example, are created by nature without pigment. The surfaces of butterfly wings diffract light to create structural color that is pigment-free and that lasts longer.
In the new paint, the colorless materials are aluminum and aluminum oxide.
How Structural Paint Is Better Than Pigment
That's all cool, but how does structural paint surpass pigment paint? According to the researchers, the advantages are significant.
Because it controls the way light is "reflected or scattered" instead of absorbing it, structural paint is more stable over time, meaning the colors won't fade. That means there is no need to repaint a surface every few years. Another environmental benefit is that these new paints would be manufactured with only metals and oxides rather than artificial pigments and chemicals.
Most exciting, thanks to its structure, plasmonic paint is lighter in two ways.
First, it reflects light and absorbs less heat, keeping its surface 25 to 30 degrees Fahrenheit (minus 3.8 to minus 1.1 degrees Celsius) cooler than a surface painted with standard commercial paint, according to UCF Today. This can have big benefits for keeping buildings cooler, thereby requiring less use of indoor cooling mechanisms.
Second, the paint weighs a lot less than traditional paint. In fact, "the structural color paint offers 100 percent reflection with only a single ultrathin layer of pigment," noted the researchers. The weight of paint might not seem like a big concern, but it is if you are an airplane. According to ScienceAlert, it would be a difference of about 1,000 pounds (454 kilograms) on a Boeing 747, which would result in huge savings in the use and cost of fuel on each flight.
Now That's Interesting
Scientists have developed engineered-structure colors in the past; however, they haven't been able to consistently display a specific color, and their fabrication techniques have made them too costly for commercial viability, according to the researchers.
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