Researchers Develop Nanoparticle Paint Inspired by Butterfly Wings

Plasmonic paint applied to the wings of metal butterflies (Credit: University of Central Florida) Every paint in the world today takes on a specific color due to the presence of pigment molecules. They absorb some wavelengths of light and reflect others, but University of Central Florida researcher Debashis Chanda has devised an entirely new kind of paint inspired by butterfly wings. The so-called plasmonic paint uses nanoscale particles to create different colors without requiring multiple pigments.

Some pigments have been used for thousands of years, and others are more recent synthetic creations. The main drawback to this kind of coloration is that you need a new molecule for every color. In addition, some pigment molecules are rare or even toxic. For example, Cobalt Blue is one of the most popular shades of blue, but this mix of cobalt oxide and aluminum oxide is dangerous if ingested or inhaled.

Chanda based the plasmonic paint on butterfly wings, which have a property known as structural color. In butterflies, the geometric arrangement of colorless materials can reflect, scatter, and absorb light to produce different colors. The paint works in a similar way using aluminum and aluminum oxide nanoparticles. Chanda and his team created the starting material by coating a mirror with nanoparticles. The distance between the particles determines how it interacts with light and, therefore, the color we perceive when looking at it. To turn those surfaces into paint, the team chipped the nanoparticles off and mixed the flakes with a commercial binding agent.

Traditional paint fades over time due to the pigment molecules losing their ability to absorb photons. That’s not a problem with the nanotech paint described in the new study. The nanoparticles don’t change over time — they always refract light the same way. “Once we paint something with structural color, it should stay for centuries,” says Chanda.

Color flakes are mixed in a solution to create paint (Credit: University of Central Florida)

Photonic paint has some other useful qualities. Because it has a large area-to-thickness ratio, you need less paint to get the job done (a layer about 150 nanometers thick). Chanda estimates you’d need just three pounds of plasmonic paint to cover a Boeing 747, which usually requires more than 1,000 pounds of standard paint. That could mean major fuel savings. Plus, plasmonic paint reflects the entire infrared spectrum, keeping the material underneath 25 to 30 degrees Fahrenheit cooler compared with commercial paint, reducing energy usage on cooling.

Next, the team plans to conduct more research on the potential energy-saving properties of the paint and prove that it can be a viable commercial product. Currently, plasmonic paint can only be made in small batches with laboratory equipment, but commercial paint needs to be produced in much larger quantities.

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