US researchers have developed a new nano-coating that only requires a very thin layer to produce sufficient color effects
Scientists in the United States have invented a new type of nano-coating that can be made into a very light coating using only a very small amount of material, only 0.4 grams per square meter, setting a record.
The team of the University of Central Florida recently published an article in the American journal Science Advances, saying that the traditional paint of the Boeing 747, about 500 kilograms, can be replaced by paint weighing only 1.3 kilograms. The production method is quite simple and applicable to various surfaces. This nano-coating uses a color generation technology called "structural color", which uses the physical and optical properties of the material's microstructure to present colors without the use of pigments.
Structural color phenomena exist naturally in many forms, including butterfly wings and peacock feathers. All coating systems used in various stages of commercialization rely on pigments and produce color effects by absorbing specific wavelengths of light by pigment molecules. Nanostructured color coatings should be more stable than pigment coatings, never fade, and cause less pollution. Existing methods for preparing these coatings have always been expensive and inefficient, and are not suitable for large-scale production. At the University of Central Florida, researchers used an aluminum mirror layer as a substrate, coated it with aluminum oxide, and then deposited aluminum nanoparticles on the substrate using a technique commonly used in the semiconductor industry to form unconnected archipelagos of "nano-islands".
The sandwich structure consisting of this "nano-island" particle layer, aluminum oxide layer and aluminum mirror has some unique optical properties. The distance between each "nano-island" and the thickness of the aluminum oxide layer determine which wavelength of light the structure can resonate with and what color it presents. Different deposition speeds change the color of the color material. During the preparation process, the entire structure is attached to a thick layer of water-soluble polymer film. After preparation, the polymer is removed to form a fragmented nanostructured color material. The researchers mixed this material with linseed oil to develop a coating that may be suitable for a variety of surfaces.
The results show that a coating of 100 to 150 nanometers can present a full-color effect, while traditional coatings require a thickness of several microns (1 micron = 1000 nanometers) to present a full-color effect. In addition, due to some inherent characteristics of the structural color phenomenon, such materials often have a rainbow effect, that is, the color seen from different angles is different, which makes it unacceptable in many coating applications. The new material overcomes this shortcoming to a certain extent and therefore has further application prospects.
