More proof, if needed, of how carbon nanotubes are a practical source of raw materials came to light a few days ago when BMW put on display their SUV X6 painted in Vantablack, the world’s darkest black.
Developed by nanotechnology specialists at the University of Surrey in 2014, Vantablack is actually neither a colour pigment nor a paint, but a coating of high aspect-ratio carbon nanotubes (CNTs), equally spaced and aligned into a ‘forest’. A nanocoating that is able to absorb 99.96% of light.
The ‘vanta’ in Vantablack stands for Vertically Aligned Nano Tube Array.
The researchers have since established their nanotube technology as a commercial enterprise called Surrey Nanosystems, whose website describes how the nanocoating is made of, “A CNT array patterned and spaced to allow photons to enter. Most of the light, or radiation arriving at the surface enters the space between the CNTs and is repeatedly reflected between tubes until it is absorbed and converted to heat. This heat (largely undetectable in most applications) is conducted to the substrate and dissipated. The Vantablack array is very largely free space; the volume of CNTs only makes up about 0.05% of the coating.” As a result, “One square metre of coating weighs around 2.5g.”
Such is the depth of blackness in the original nanocoating that the SUV had to be coated in a newer version of the substance called VBX2. Because, as the technology journal The Verge explains, “This Vantablack variant allows for the slightest bit of light reflection while remaining ‘super black’, according to Surrey NanoSystems founder Ben Jensen.”
At present, safety concerns make it unlikely that BMW will be applying the nanocoating to more than the one car that is set to go on display at the Frankfurt Motor Show in September 2019. However, not only is the coating drawing attention to BMW’s range of automobiles, it is also highlighting the wide range of applications for carbon nanotubes.
Already a wide variety of industries are taking advantage of the unique properties carbon nanotubes contain. As a raw material, the ability to control the properties that CNTs will have during manufacturing make them ideal for solving all manner of engineering problems. CNTs can be flexible or rigid, electrically conductive or non-conductive, are lightweight, yet strong, and now come in a variety of colours.
Photo credit: Theoutline, BMW, & Surrey Nanosystems