Researchers have developed a new energy-efficient paint that repels heat, is available in any color and should last for centuries. It is also the lightest paint created to date.
Inspired by butterfly wings, this painting is not made of pigment. Instead, the color is created structurally by the arrangement of nanoparticles. The team calls it “plasmonic painting”.
According to their calculations, it would suffice 1.4 kilograms (3 pounds) of plasmonic paint to cover a Boeing 747 – it would take at least 454 kilograms (1,000 pounds) of conventional commercial paint to do the same thing.
This means it could significantly reduce the amount of greenhouse gases needed for flight.
To be clear, this paint was only created in the lab, so we are far from producing it en masse.
But the researchers have already made the paint in different colors using techniques that can easily be scaled up, and that’s what they’ll be working on next.
One of the main motivating factors for bringing this paint to market is that it can also help keep structures cooler: the plasmonic paint structure reflects the full infrared spectrum, so less heat is absorbed.
THE say the researchers that surfaces under new paint stay 13 to 16 degrees Celsius (25 to 30 degrees Fahrenheit) cooler than if coated with regular commercial paint.
“More than 10% of the total electricity in the United States is for the use of air conditioners”, says nanoscientist Debashis Chanda from the University of Central Florida, who led the team that created the painting.
“The temperature difference promised by the plasmonic paint would result in significant energy savings. Using less electricity for cooling would also reduce carbon dioxide emissions, thereby mitigating global warming.”
Currently, pigment-based paints require specific molecules to build color, and typically, in modern paints, these pigments are artificially synthesized.
The electronic properties of each molecule control the amount of light absorbed and, therefore, the color of the paint. This means that there must be a new pigment for each new paint color.
Instead, the plasmonic paint uses the nanoparticles of two colorless materials – aluminum and aluminum oxide. By arranging them in different ways on an oxide-coated aluminum mirror, it is possible to control how light is scattered, reflected or absorbed.
A similar process is responsible for the rich color of butterfly wings.
“The range of colors and hues in the natural world [is] amazing – from colorful flowers, birds and butterflies to underwater creatures like fish and cephalopods” Chanda said.
“Structural color serves as the primary color-generating mechanism in several extremely vivid species where the geometric arrangement of two generally colorless materials produces all colors. On the other hand, with [human-made] pigment, new molecules are needed for each color present.”
The structural color is what makes the paint so light – at a thickness of just 150 nanometers the paint achieves full coloring, making it the the lightest painting ever recorded.
In this research, the team created the structural painting using a electron beam evaporator which heats a substance at a highly controlled rate.
This controlled evaporation allows small groups of aluminum nanoparticles to self-assemble – the aluminum atoms are more attracted to each other than the oxide substrate on which they grow, so they s clump together naturally.
By adjusting the pressure and temperature of the electron beam evaporator, the team can create structures that reflect different colors.
“Essentially, this pressure and temperature controlled process ensures high reproducibility over large areas in a single step, reducing production cost and enabling large-scale manufacturing,” the team writes in their article.
The researchers also combined their structural color flakes with a commercial binder, which means the paint will last for hundreds of years, at least in theory.
“Normal color fades as the pigment loses its ability to absorb photons,” said Chanda.
“Here, we are not limited by this phenomenon. Once we paint something with structural color, it should remain for centuries.”
It’s not the first new type of paint to promise incredible properties. Many of you will have heard of vantablack – one of the blackest paints in the world, capable of absorbing 99.96% of light.
Similar to plasmonic paint, this super blackness is the result of tiny carbon nanotubes, and even blacker paintings have been created on the same method ever since.
There is also super white paint, which reflects 98.1% of all light and promises to significantly reduce air conditioning requirements. But unlike plasmonic paint, ultra-white paint relies on pigments to reflect light, and Vantablack currently only comes in one color.
Still, there’s still a long way to go before we all customize our own plasmonic paint colors and use just one little box to paint an entire house.
“Conventional pigmented paint is made in large facilities where you can produce hundreds of gallons of paint,” said Chanda.
“Right now, unless we go through the scaling process, it’s still expensive to produce in a university lab.”
The research has been published in Scientific advances.