Color is an important source of sensations and has motivated people to develop more and better dyes. The search for purer, fade-resistant, and ecologically acceptable dyes has lasted from Paleolithic cave paintings to the development of synthetic dyes. Dye research has found applications in display technologies, optical storage, sensing and treatments, and functional coatings over the past few decades.
Coloring technique can be achieved by controlling the absorbing or reflecting response of the dye to white light, while structural dyes hold how the light is reflected or scattered. The study aims to create the first environmentally friendly, large-scale, multicolored and self-contained platform for giving nanostructured coloring to any surface, bridging the gap from proof of concept to industrial production.
Inspired by butterflies, researcher Debashis Chanda of the University of Central Florida has created the first eco-friendly, large-scale, multi-color alternative to pigment-based dyes, which could contribute to energy conservation 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 such as fish and cephalopods. Structural color serves as the primary color-generating mechanism in several extremely vibrant species where a geometric arrangement of typically two colorless materials produces all colors.On the other hand, man-made pigments require new molecules for each color present.”
The recently revamped plasmonic paint uses a nanoscale structural arrangement of colorless materials, aluminum and alumina instead of pigments to create colors.
While pigment dyes control light absorption based on the electronic property of the pigmenting material, and therefore each color needs a new molecule, structural dyes prevent the way light is reflected, scattered, or absorbed based purely on the geometric arrangement of nanostructures. They are environmentally friendly as they use only metals and oxides, unlike today’s pigment based colors which use artificially synthesized molecules.
The researchers combined their structural color flakes with a commercial binder to form long-lasting paints in all colours.
He said, “Normal color fades because pigment loses its ability to absorb photons. Here we are not limited by that phenomenon. Once we paint something with structural color, it should last for ages.
The researcher said, “As a child I always wanted to build a butterfly. Color attracts my interest.”
The paint reflects the entire infrared spectrum. It absorbs less heat, keeping the underlying surface 25 to 30 degrees Fahrenheit cooler than when covered with standard commercial paint. The paint is also extremely lightweight, thanks to its large surface area to thickness ratio.
He added, “More than 10% of the total electricity in the US goes to the use of air conditioning. The temperature difference that plasmonic paint promises would lead to significant energy savings. Using less electricity for cooling would also reduce carbon dioxide emissions, reducing global warming.”
The paint is the lightest in the world, with a thickness of only 150 nanometers. It is so light that just 3 pounds of plasmonic paint can 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 large factories where they can make hundreds of liters of paint. Unless we go through the scale-up process, producing in an academic lab is still expensive. We need to bring something different, like non-toxicity, cooling effect, ultra-light weight, 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 a commercial paint.
The result shows that nature presents a variety of chemical and structural compositions.
Magazine reference:
- Daniel Franklin, Debashis Chanda, et al. Ultralight Plasmonic Structural Color Paint. Scientific progress. DOI: https://doi.org/10.1126/sciadv.adf7207
