Here comes the lightest paint
Researchers in the United States have developed a new nano-paint that needs only an extremely thin layer to produce a sufficient color effect. At just 0.4 grams per square meter, it is the lightest coating available.
A team at the University of Central Florida reported in the journal Science Advances that a Boeing 747 would need only 1.3kg of conventional paint, compared with about 500kg of conventional paint. The new paint production process is relatively simple and can be applied to a variety of surfaces.
The nano paint uses a color rendering technique known as "structural color," which uses the physico-optical properties of a substance's microscopic structure to render colors without the need for pigments. Structural color phenomena exist widely in nature, such as butterfly wings, peacock feathers and so on.
Current commercial paints are based on pigments, which produce color effects by absorbing specific wavelengths of light from pigment molecules. Nanostructured color paints are more stable than pigment paints, do not fade and pollute less. But previous methods of preparing such coatings tended to be costly and inefficient, making them unsuitable for mass production.
Researchers at the University of Central Florida used a mirror layer of aluminum as a substrate, coated with aluminum oxide, and then used electron beam evaporation, a technique widely used in the semiconductor industry, to deposit aluminum nanoparticles onto the substrate, forming unconnected "nanoislands." This "nano-island" particle layer is composed of alumina layer and aluminum mirror sandwich structure has unique optical properties. The distance between the nanoislands, as well as the thickness of the alumina layer, determines what wavelength of light the structure resonates with and what colour it appears. Adjusting the deposition rate can change the colour of the material.
During preparation, the entire structure is attached to a layer of water-soluble polymer, which is removed after preparation to obtain a fragmented nanostructured color material. The researchers mixed the material with linseed oil to create a paint that could be applied to a variety of surfaces. The results show that a coating between 100 and 150 nanometers thick can achieve a full color effect, compared with a few microns (1 micron = 1,000 nanometers) for traditional coatings.
In addition, due to the inherent nature of the structural color phenomenon, in the past such materials tended to have an irido effect, that is, different colors are seen from different angles, which is not appropriate in many coating applications. The new material overcomes this shortcoming to a large extent and thus has a broader application prospect.
