Termites and ants can do a lot of damage to buildings, especially in the tropics. Aurélie Féat got her PhD for a study of bio-coatings that the little insects slide off.
Insects damage buildings to the tune of between 2 and 40 billion dollars a year, estimates Féat. Termites are the worst, mainly in Africa and Asia. You can combat them with insecticides, but paint manufacturer AkzoNobel is looking for a less toxic alternative: a paint that the insects cannot get a grip on. This quest brought Féat to Jasper van der Gucht, professor of Physical Chemistry and Soft Matter.
'Biologists in Cambridge discovered how insects walk up walls,' says Van der Gucht. 'They excrete a fluid that works like glue so they can stick to surfaces, or they use their claws to cling on.' So Féat set about creating several kinds of paint on which these tactics wouldn't work.
The best option, which all ants slid off, turned out to be a badly mixed paint. 'Paint is a complex mixture of pigments, polymers and binders,' explains van der Gucht. 'If you mix paint badly, pigment particles stick out from the surface, and those particles get stuck on the ant's feet. After that, the gluey fluid stops working.' A nice cheap solution, concludes the professor: keep ants away with badly mixed paint.
Another successful paints was one with large particles. 'Thanks to those large particles, the surface becomes raw and pores form. We think the ants' sticky fluid gets absorbed by these pores and that makes them fall off the wall.' A bit of chalk in the paint will do the trick, discovered Féat.
It will take a while before insect-resistant paint is for sale, thinks Van der Gucht, because the paint manufacturer still need to fine-tune some other paint characteristics. AS
