Coated in nano-controversy?

Materials World magazine
1 Nov 2009

Nano-enabled coatings have been widely championed over the last decade with properties ranging from UV protection through to abrasion resistance and self-cleaning surfaces. But this has not been enough to overcome the inertia of the manufacturing community and promote change, according to the UK Nanotechnology Knowledge Transfer Network (NanoKTN). To-date, applications commercialised successfully have been small volume, high added value products.

Delegates at the Nano-enabled Coatings event, held on 23 September in London, UK, believe the time has arrived for the breakthrough into large volume, mass applications, although several obstacles still need to be overcome before this goal can be achieved. The seminar, hosted by the NanoKTN, acted as a forum for those wishing to build or develop supply chains to expedite commercialisation.

‘Nanomaterials have been hamstrung with health and safety concerns, confusion over terminology and a general perception as “materials in search of an application”, all of which need to be overcome before they can truly become the default choice for formulators’, said Andrew Jackson of Information Research, based in London, UK.

‘From a health and safety perspective, the difficulties the sector faces are exemplified by the polarisation created by carbon nanotubes. These are among the most well known nanoadditives to date, due to their ability to reinforce film structure, improve scratch resistance, flaking and delamination characteristics,’ he explained. ‘However, their similarity to asbestos fibres has raised serious concerns about including them in coatings formulations, especially as particles may be abraded during refinishing processes. Until conclusive evidence can endorse their safety, most, if not all, nanomaterials designed are viewed with suspicion’.

Talking to Materials World after the event Jackson added, ‘So far, there has been marginal progress in the way of a resolution. However, nearly all of the coatings industry agrees that there is no inherent risk of exposure to harmful moieties once the coating is cured, whereupon they become locked inside the coatings’ polymer matrices.’

One delegate argued that a second factor preventing widespread uptake is the confusion surrounding the definition of what qualifies as a ‘nano’ coating. He said until governing bodies can develop a coordinated plan of action to draw a line under what a nanomaterial, and in turn a nanocoating, actually constitutes, there would be continued debate.

Jackson agreed, joking that the only way forward would be to have a moratorium to turn off the coatings industry in order to establish what can and cannot be allowed.

‘There is a huge issue with respect to the nomenclature of nanotechnology within the industry’, he said. ‘I think the most likely solution will be to drop the  “nano” prefix to allow the materials to be categorised as just “another” additive. Effectively there will be a paradigm shift and these materials will gradually displace current offering.’

On a slightly different note, Diana Barbosa, Managing Director of SEAS Nanosolutions, based in  Bristol, UK, presented the company’s work on photocatalyst coatings that can be sprayed on surfaces to prevent the spread of desease by inhibiting the build up of bacteria. The self-sanitising barrier is said to last up to five years.

‘By diminishing the need to use water and chemical disinfectants, use of the new, non-toxic coatings reduces the amount of waste chemicals going into the ecosystem, as well as reducing cleaning and disinfection time,’ explained Barbosa.

This technology uses the antimicrobial, self-cleaning and air purification properties of nano-titanium dioxide, which breaks down organic chemical pollutants and destroys the cells of micro-organisms, giving it an antibacterial quality that is even stronger than chlorine or peroxide, she says.

Further information: NanoKTN 

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