Traditional paint is made from a binding agent (such as oil) and heavy metal pigments—cobalt, ocher, and cadmium—which produce blue, red, and yellow colors, respectively. But researchers at the University of Central Florida (UCF) tried to follow nature’s lead in creating vibrant palettes – and accidentally created the world’s lightest paint.
Animals acquire color in a variety of ways—for example, the submicroscopic projections and contours of peacock feathers diffract light, creating iridescent blues and greens. This is the so-called structural coloration, which is also used by many species of beetles and butterflies – and scientists from Florida have developed a paint that can imitate it.
Initially, the researchers tried to create a long aluminum mirror using an electron beam evaporator. After numerous failures, they noticed that the aluminum particles “stick together” to create microscopic “nanoislands”, which prevented the creation of a surface with a high level of light reflection.
The team also noticed that aluminum’s electrons were “excited” whenever light hit the nanoparticles, causing them to vibrate. In addition, the electrons resonated with different wavelengths of light depending on the size of the nanoparticles: white light hitting the uneven surface was reflected around its ridges before finally being reflected in a single color.
“Just by changing the size of the nanoparticles, you can actually create different colors,” said Debashis Chanda, co-author of the study.
The researchers set about creating different colors of paint by growing aluminum “nanoislands” in a double-sided mirror and turning them into a powder-like consistency. Next, the material was mixed with a binding agent to obtain the finished paint.
Structural scattering is the mechanism that was used to create the UCF ink. Lamellar nanostructures found in butterfly wings (and peacock feathers) scatter the blue components of light, producing a distinctive metallic blue color.
Chanda said that due to the structural nature of the material, a very thin layer is required to paint the surface. Drops the size of raisins can be enough to stain doors on both sides. This property makes the paint ultra-light, a potentially useful invention for the aviation industry.
A Boeing 747 requires about 450 liters of conventional paint, but with the paint the Florida researchers invented, it only takes 1.3 liters. This seems insignificant for an aircraft that weighs several hundred tons, but even a small weight saving is accompanied by huge fuel savings.
“Given that fuel is a significant part of operating costs [около 30% в прошлом году]airlines are interested in improving fuel efficiency,” said a spokesman for the International Airline Association.
For example, American Airlines calculated that it saved 400,000 gallons of fuel and $1.2 million a year by removing 30kg of pilot benefits from its aircraft. The company claims to have saved another 300,000 gallons in 2021 by switching to a lighter paint that dropped 28kg off the 737s.
Another advantage of this type of paint is its durability. Airlines repaint their planes up to four times a year due to the influence of the sun – structural paints do not fade.
Finally, the paint will help keep the temperature down. Most planes are built white to reflect as much light as possible. Preliminary tests show that the team’s dye maintains surface temperatures 20-30℉ lower than traditional paint, regardless of color. Therefore, it is ideal for painting airplanes, cars, houses and other buildings – if it can lower the temperature inside even a few degrees, this will save a lot of energy used for air conditioning.
The only problem researchers are currently facing is scalability. They have the equipment to make small bottles, but for real commercialization, they will have to produce much more. The laboratory is looking for partners who would help bring the product to market.
The study was published on March 8 in the scientific journal Science Advances.
Source: UCF, Techspot
