from the I-see-your-true-color-plasmonic-cavity-reflecting-back dept.
An energy-saving coating needs no pigments, and it keeps the surface beneath it 30 degrees cooler:
Color surrounds us in nature, and we re-create it with pigments. You can think of pigments as pulverized minerals, heavy metals, or chemicals that we swish into oil and spread over a canvas or car: Cobalt becomes blue; ochre red; cadmium yellow. "But nature has a very different way of creating color than we do," Chanda says. Some of nature's most vivid looks—the kind worn by peacocks, beetles, and butterflies—do their thing without pigment.
Those colors come from topography. Submicroscopic landscapes on the outer surfaces of peacock feathers, beetle shells, and butterfly wings diffract light to produce what's known as structural color. It's longer-lasting and pigment-free. And to scientists, it's the key to creating paint that is not only better for the planet but might also help us live in a hotter world.
In a paper published this month in Science Advances, Chanda's lab demonstrated a first-of-its-kind paint based on structural color. They think it's the lightest paint in the world—and they mean that both in terms of weight and temperature. The paint consists of tiny aluminum flakes dotted with even tinier aluminum nanoparticles. A raisin's worth of the stuff could cover both the front and back of a door. It's lightweight enough to potentially cut fuel usage in planes and cars that are coated with it. It doesn't trap heat from sunlight like pigments do, and its constituents are less toxic than paints made with heavy metals like cadmium and cobalt.
[...] Because structural color can blanket an entire surface with just a thin, ultralight layer, Chanda thinks this will be a game changer—for airlines. A Boeing 747 needs about 500 kilograms of paint. He estimates that his paint could cover the same area with 1.3 kilograms. That's more than 1,000 pounds shaved off each plane, which would reduce how much fuel is needed per journey.
[...] Structural paint may also last longer. (Some airlines repaint planes every four years.) Pigment molecules break down in sunlight but structural color doesn't—so it doesn't fade. "We have all these ways of trying to fix pigment, to try to prevent it from oxidizing and losing its color. Or it fades and we throw it in the landfill," says Baumeister, who is also a cofounder of consultancy Biomimicry 3.8. "But when you need color to last forever—for the life of the organism—structural color is preferred."
Chanda's team also realized that, unlike conventional paint, structural paint doesn't absorb infrared radiation, so it doesn't trap heat. ("That's the reason your car gets hot in the hot sun," he says.) The new paint is inherently cooling in comparison: Based on the lab's preliminary experiments, it can keep surfaces 20 to 30 degrees Fahrenheit cooler than conventional paint.
Journal Reference:
Pablo Cencillo-Abad, Daniel Franklin, Pamela Mastranzo-Ortega, et al., Ultralight plasmonic structural color paint, Science Advances, 2023. DOI: 10.1126/sciadv.adf7207
(Score: 0) by Anonymous Coward on Tuesday April 11, @02:33AM
Don't ground it up finely? https://en.wikipedia.org/wiki/Tian-tsui [wikipedia.org]
https://store.museumofjewelry.com/collections/tian-tsui [museumofjewelry.com]
https://www.etsy.com/market/tian_tsui [etsy.com]
(Score: 2, Interesting) by pTamok on Tuesday April 11, @08:10AM (1 child)
Paint is often (perhaps mostly) used as protection for the underlying surface, with colour being an incidental by-product or an added option - e.g. Marine anti-fouling paint; paint on wooden buildings to protect them from the climate (the distinctive red colour of many Swedish rural wood cabins is due to the use of a special paint that contains iron oxide [smithsonianmag.com])
While the idea of pigments that don't fade is great, the protective qualities of paint may well mean that the colour needs to be incorporated as a pigment particles in a varnish, which is just a fancy way of saying a kind of 'paint' (note that pigments are insoluble in water, whereas dyes dissolve). This means that the idea of replacing paint on aeroplanes as a weight saving might not be practicable, as the paint is a protective surface as well as a colour. Painting aeroplanes is hard, as it is a brutal environment: High UV, and wild swings in temperature (which means the underlying surface expands and contracts), which makes aeroplane paint rather special. Military aircraft with 'radar-absorbing' paint are a whole additional (and expensive) level of difficulty. The Concorde commercial supersonic plane was white to help deal with heat caused (among other things) by supersonic flight [stackexchange.com] ( See also: https://en.wikipedia.org/wiki/Concorde#Heating_problems [wikipedia.org] ).
There's a general human assumption that light- and white- coloured paints reflect heat, and dark- and black-coloured paints absorb heat. This correlation doesn't always hold, as the infra-red absorption/emission spectra, can be very different to the optical spectrum - a shiny reflective metal surface can have very good infra-red absorptance/emittance.
Nonetheless, having a stable, non-toxic colour-tunable pigment would be great.
(Score: 2) by hendrikboom on Tuesday April 11, @05:57PM
Colour-tunable? Any hope of using it for e-ink?
(Score: 0) by Anonymous Coward on Tuesday April 11, @05:30PM
in 10 years or 20. And as an affordable paint when the patents expire + couple years.
Slava Ukraini! Slay the orcs!
(Score: 2) by sonamchauhan on Wednesday April 12, @05:33AM
Can we not add aluminium nanoparticles to the environment? There evidence of Al toxicity causing Alzheimer's