Color is an important source of sensations, and it has motivated humans to develop more and better colorants. The search for purer, fade-resistant, and ecologically acceptable colorants has lasted from Paleolithic cave paintings until the development of synthetic dyes. Colorant research has found applications in display technologies, optical storage, sensing and treatments, and functional coatings throughout the last few decades.
Color engineering can be achieved by controlling the colorant’s absorptive or reflective response to white light, while structural colorants hold how the light is reflected or scattered. The study aims to create the first environmentally friendly, large-scale, multicolor, and self-standing platform for imparting nanostructured coloration to any surface, bridging the gap from proof of concept to industrial production.
Inspired by butterflies, University of Central Florida researcher Debashis Chanda has created the first environmentally friendly, large-scale, and multicolor alternative to pigment-based colorants, which can contribute to energy-saving efforts and help reduce global warming.
Chanda said, “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. Structural color serves as the primary color-generating mechanism in several extremely vivid species where a geometrical arrangement of typically two colorless materials produces all colors. On the other hand, with manmade pigment, new molecules are needed for every color present.”
The newly innovated plasmonic paint utilizes a nanoscale structural arrangement of colorless materials, aluminum, and aluminum oxide instead of pigments to create colors.
While pigment colorants control light absorption based on the electronic property of the pigmenting material, and hence every color needs a new molecule, structural colorants prevent the way light is reflected, scattered, or absorbed based purely on the geometrical arrangement of nanostructures. They are environmentally friendly as they only use metals and oxides, unlike present pigment-based colors that use artificially synthesized molecules.
The researchers have combined their structural color flakes with a commercial binder to form long-lasting paints of all colors.
He said, “Normal color fades because pigment loses its ability to absorb photons. Here, we’re not limited by that phenomenon. Once we paint something with structural color, it should stay for centuries.”
The researcher said, “As a kid, I always wanted to build a butterfly. Color draws my interest.”
The paint reflects the entire infrared spectrum. It absorbs less heat, resulting in the underneath surface staying 25 to 30 degrees Fahrenheit cooler than if covered with standard commercial paint. The paint is also extremely lightweight, thanks to its large area-to-thickness ratio.
He added, “Over 10% of total electricity in the U.S. goes toward air conditioner usage. 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 paint is the lightest in the world, with a thickness of only 150 nanometers. It is so lightweight that only 3 pounds of plasmonic paint could cover a Boeing 747, which usually requires more than 1,000 pounds of conventional paint.
He also said. “The conventional pigment paint is made in big facilities where they can make hundreds of gallons of paint. Unless we go through the scale-up process, producing at an academic lab is still expensive. We need to bring something different, like non-toxicity, cooling effect, ultralight weight, to the table that other conventional paints can’t.”
The vibrancy of butterflies inspires the research, and the project’s next steps include further exploration of the paint’s energy-saving aspects to improve its viability as commercial paint.
The result shows that Nature presents a variety of chemical and structural compositions.
- Daniel Franklin, Debashis Chanda, et al.Ultralight plasmonic structural color paint. Science Advances. DOI: https://doi.org/10.1126/sciadv.adf7207