Butterflies inspire world’s first energy-saving paint
10 March 2023
A new way to produce coloured paint is more natural, environmentally friendly and lightweight.
University of Central Florida researcher Debashis Chanda, a Professor in UCF’s NanoScience Technology Center, has drawn inspiration from butterflies to create the first environmentally friendly, large-scale and multicolour alternative to pigment-based colourants, which can contribute to energy-saving efforts and help reduce global warming.
“The range of colours and hues in the natural world is astonishing – from colourful flowers, birds and butterflies to underwater creatures like fish and cephalopods,” Chanda says.
“Structural colour serves as the primary colour-generating mechanism in several extremely vivid species where geometrical arrangement of typically two colourless materials produces all colours.
“On the other hand, with manmade pigment, new molecules are needed for every colour present.”
Based on such bio-inspirations, Chanda’s research group innovated a plasmonic paint, which utilises a nanoscale structural arrangement of colourless materials – aluminium and aluminium oxide – instead of pigments to create colours.
While pigment colourants control light absorption based on the electronic property of the pigment material and hence every colour needs a new molecule, structural colourants control the way light is reflected, scattered or absorbed based purely on the geometrical arrangement of nanostructures.
Such structural colours are environmentally friendly as they only use metals and oxides, unlike present pigment-based colours that use artificially synthesised molecules.
The researchers have combined their structural colour flakes with a commercial binder to form long-lasting paints of all colours.
“Normal colour 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 colour, it should stay for centuries.”
Additionally, because plasmonic paint reflects the entire infrared spectrum, less heat is absorbed by the paint, resulting in the underneath surface staying 25 to 30 degrees Fahrenheit cooler than it would if it were covered with standard commercial paint, the researcher says.
“Over 10 percent of total electricity in the US goes toward air conditioner usage,” Chanda says. “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.”
Plasmonic paint is also extremely lightweight, the researcher says.
This is due to the paint’s large area-to-thickness ratio, with full colouration achieved at a paint thickness of only 150nm, making it the lightest paint in the world, Chanda says.
The paint is so lightweight that only about 3lb of plasmonic paint could cover a Boeing 747, which normally requires more than 1,000lb of conventional paint, he says.
Chanda says his interest in structural colour stems from the vibrancy of butterflies.
“As a kid, I always wanted to build a butterfly,” he says. “Colour draws my interest.”
Chanda says the next steps of the project 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,” he 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,” Chanda says.