Debashis Chanda drew inspiration from butterflies to create the innovative new plasmonic paint, shown here applied to metal butterfly wings. Photo: University of Central Florida.
Debashis Chanda drew inspiration from butterflies to create the innovative new plasmonic paint, shown here applied to metal butterfly wings. Photo: University of Central Florida.

Debashis Chanda, a professor in the University of Central Florida’s NanoScience Technology Center, has drawn inspiration from butterflies to create the first environmentally friendly, large-scale, multicolor alternative to pigment-based colorants. These new colorants can contribute to energy-saving efforts and help to reduce global warming. Chandra and his colleagues report their work in a paper in Science Advances.

“The range of colors and hues in the natural world are astonishing – from colorful flowers, birds and butterflies to underwater creatures like fish and cephalopods,” Chanda says. “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.”

Based on such bio-inspirations, Chanda’s research group developed a novel plasmonic paint, which utilizes a nanoscale structural arrangement of colorless materials – aluminum and aluminum oxide – instead of pigments to create different colors.

While pigment colorants control light absorption based on the electronic property of the pigment molecule, and hence every color requires a new molecule, structural colorants control the way light is reflected, scattered or absorbed based purely on the geometrical arrangement of nanostructures. Structural colors are environmentally friendly, as they only use metals and oxides, unlike pigment-based colors that use artificially synthesized molecules.

In this study, the researchers combined their structural color flakes with a commercial binder to form long-lasting paints of all colors.

“Normal color fades because pigment loses its ability to absorb photons,” Chanda says. “Here, we’re not limited by that phenomenon. Once we paint something with structural color, it should stay for centuries.”

Additionally, because plasmonic paint reflects the entire infrared spectrum, less heat is absorbed by the paint, resulting in the surface underneath staying 25–30°F cooler than it would if it were covered with standard commercial paint.

“Over 10% of total electricity in the US goes toward air conditioner usage,” Chanda explains. “The temperature difference plasmonic paint promises would lead to significant energy savings. Using less electricity for cooling would also cut down carbon dioxide emissions, lessening global warming.”

The plasmonic paint is also extremely lightweight. This is due to the paint’s large area-to-thickness ratio, with full coloration achieved at a paint thickness of only 150nm. According to Chandra, this makes it the lightest paint in the world. The paint is so lightweight that only about three pounds could cover a Boeing 747, which normally requires more than 1000 pounds of conventional paint.

Chanda says that his interest in structural color stems from the vibrancy of butterflies. “As a kid, I always wanted to build a butterfly. Color draws my interest.”

The next steps of the project will include further exploration of the paint’s energy-saving aspects to improve its viability as commercial paint.

“The conventional pigment paint is made in big facilities where they can make hundreds of gallons of paint,” Chandra says. “At this moment, unless we go through the scale-up process, it is still expensive to produce at an academic lab.

“We need to bring something different like non-toxicity, cooling effect, ultralight weight to the table that other conventional paints can’t.”

This story is adapted from material from the University of Central Florida, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.