Dayna Baumeister, co-director of the Center for Biomimicry at Arizona State University, isn’t surprised that paint has so many hidden functions. It’s a great demonstration of what’s possible,” she says.
all Nothing beats that imperfection, paint. People have used pigments for thousands of years, so the tricks to getting the right look have been mastered by paint makers. They can lighten it up or tone it down — they’ve been figuring this out for hundreds of years,” says Chanda.
New forms of paint must innovate not only in aesthetics, but also in the realm of physics. Still, members of Chanda’s lab stumbled upon their innovation by chance. They hadn’t set out to make paint. They wanted to make a mirror, specifically a long continuous aluminum mirror built using an instrument called an electron beam evaporator. But in every attempt they noticed a small “nano-island”. These are clumps of aluminum atoms that are too small to be seen, but large enough to disturb the brilliance of mirrors. Nano-islands now appeared frustratingly across the surface of what was no longer a continuous mirror. “It was really annoying,” recalls Chanda.
Then came an epiphany: the chaos was doing something usableWhen ambient white light hits the aluminum nanoparticles, it excites the electrons in the metal to vibrate or resonate. But when dimensions reach the nanoscale, atoms become even more noisy. Depending on the size of the aluminum nanoparticles, their electrons oscillate only for certain wavelengths of light. This makes the ambient light bounce off as part of the original color: a single color. The colorful effect was amplified by layering aluminum particles on the mirror-like reflective surface they were trying to create.
what color? It depends on the size of the nano-islands. “Just by shifting the dimensions, we can actually create all color,” says Chanda. Unlike pigments, which require different base molecules for each color, like cobalt or purple snail slime, the base molecule for this process is always aluminum, bits of different sizes that vibrate to light at different wavelengths. is cut to
It’s time to paint. The group’s process begins with a very thin sheet of double-sided mirror. The researchers covered each side with a clear spacer material that helps amplify the color effect. We then grew islands of metal nanoparticles on both sides of the sheet. To make this material compatible with the binders or oils used in paint, they melted the large sheets into colorful flakes as fine as powdered sugar. Finally, once I had created enough colors for the little rainbow, I was able to draw the butterfly.
Chanda sees this as a game changer for airlines, as structural colors can cover entire surfaces with just a thin, ultralight layer.A Boeing 747 requires about 500 kilograms of paint. He estimates that his paint can cover the same area with his 1.3 kilograms. This equates to more than 1,000 pounds of weight savings from him per plane, reducing the amount of fuel required per trip.
