Chemical Technology March 2016

NANOTECHNOLOGY

to suppress stray light. Solar collectors are used to absorb radiation and convert it into heat. And there are a fewmore: spectroscopy used in medical diagnostics (eg, in blood tests), cinematography (both on production and in projec- tion), and in architecture. One of Surrey NanoSystems latest developments is a spray paint version. This only absorbs 99,8 % of incident light (compared to their main product’s 99,965 %) but it can be applied at room temperature to any object. The British Science Museum currently has a display one can visit. Ben Jensen, at Surrey NanoSystems, makes a minor dig at NASA in his comments about the display: “Vantablack S-VIS is so effective that its performance far outstrips any other known paint or super-black coating, achieving a reflectance of just 0,20 %. This is significantly less reflective than, for example, the super-black paint used for managing stray-light in the Hubble Space Telescope.” Sir Anish Kapoor, an architect and sculptor, intends us- ing VantaBlack in a new artwork (after he gets his security certification because this is a listed product). Both NASA’s super-black and Surrey NanoSystems’ Van- tablack have a very wide light absorption range, including for non-visible light (many space-based sensors operate be- yond even the infrared and ultraviolet ranges). So do radar systems. Black coatings that can go on any surface, survive extreme conditions, and which reflect almost no light are rather useful in converting almost any aircraft into a stealth vehicle. But let’s put those unhappy thoughts aside for the moment and think instead of art. As Sir Anish Kapoor said when discussing his plans for VantaBlack, “Imagine a space that’s so dark that as you walk in you lose all sense of where you are, what you are, and especially all sense of time.” And that’s plenty scary on its own, wouldn’t you say?

one in nanotech: atomic layer deposition (ALD). Used most commonly in the production of microprocessors, by alternat- ing a sequence of gas deposition on a substrate, complex nanoscopic components can be created. (Chemical vapour deposition is similar to ALD but here the different vapours are never present simultaneously.) NASA’s problem is that its approach requires the oxide- coated objects to be baked at 750 °C . That seriously limits the nature of the objects they can coat as well as introduces new problems. A new spectrograph added to Hubble in 1997 underwent thermal expansion and shortened the lifespan of the instrument. In 2014, researchers at Surrey University released a paper entitled “The partial space qualification of a vertically aligned carbon nanotube coating on aluminium substrates for Earth Orbit applications”. Evangelos Theocharous, Christopher Chunnilall and their colleagues described the low-temperature fabrication of “NanoTube Black, a Verti- cally Aligned carbon NanoTube Array (VANTA) on aluminium substrates”. Low-temperature in their case means 400 °C. This massively increases the range of materials they are able to coat. Their first commercial orders were delivered to clients in July 2014. Clients in the aerospace industry tested the material for mass loss, outgassing, shock, vibration and temperature cycling. It passed happily. The Hubble is reaching the end of its work life and its successor, the James Web Space Telescope, is being de- veloped with a launch target of 2018. It’s highly likely that VantaBlack will be used as a coating. Fortunately for Surrey NanoSystems, there’s more work out there than the occasional space telescope. There are a large number of sensors which measure light but need

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Chemical Technology • March 2016