A protective coating that stops corrosion as soon as it starts has been developed by European scientists. The new coating is activated by daylight and is less toxic than before, they claim.  

Ekaterina Skorb and colleagues from the Max Planck Institute, Potsdam, Germany, encased a known corrosion inhibitor, benzotriazole, inside the pores of light-sensitive titanium nanoparticles. When exposed to UV light, a change at the nanoparticle surface switches the containers to the open state, releasing the inhibitor. This was amazing because we can see in real time, after irradiating the surface, these containers open immediately,' says Skorb. 

A self healing protective coating could prevent corrosion

 
By adding silver nanoparticles, the photosensitive range of the containers is altered making them responsive to infrared and visible light radiation, explains Skorb. So, under normal daylight conditions, any cracks or damage to the coating are healed by the release of the corrosion inhibitor directly inside the damaged area, she says.

'This work presents very promising results,' says Christian Simon, an expert in surface science and functional coatings at SINTEF (The Foundation for Scientific and Industrial Research), Trondheim, Norway. 'Especially, the fast healing effect observed after light illumination shows great potential in corrosion protection,' he adds.

The new coating has the added benefit of being safer than previous anticorrosion coatings as it avoids the use of hexavalent chromium, which can have detrimental effects on human health and the environment, adds Skorb. 

The team are now looking for other applications for these light-responsive containers. 'This strategy could be applied for the controlled release of a number of active agents,' says Skorb 'these could be biocides, lubricants or wetting agents.' 

Nicola Cogan

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