Invention, Heal Thyself !

We’ve been hearing about self-repairing materials for some time now and every year a new breakthrough is trumpeted. Tomorrow it’s the turn of Professor Duncan Wass, Bristol University School of Chemistry, who will address The Royal Society’s scientific discussion meeting “Catalysis Improving Society”. He will outline the work of his group in the use of catalysts in self-healing composite materials. Sounds boring? – Quite the opposite.

This technology has exciting and far-reaching possibilities. Carbon fibre composites, due to their strength and weight reducing capabilities, are rapidly becoming must-have’s – especially in the aerospace and automotive industries. Trouble is, these materials can be prone to cracking under stress. A somewhat troubling thought for frequent flyers – these composites are used in the manufacture of aircraft wings!

The Bristol team have overcome this by suffusing the materials with microspheres which rupture in the damage areas and release a liquid which, on meeting an already impregnated catalyst, chemically react to ‘heal’ the damage. Laboratory tests have shown that the ‘healed’ materials are as strong as the originals. What’s more exciting is that this is an automatic process – the materials self-repair whilst on-the-go.

It’s not just aircraft wings, we could soon see all manner of self-healing products from tennis racquets to motorcycle helmets. The team have even been contacted by L’Oreal who see the possibilities in self-repairing nail polish. “We’re definitely getting to the stage where in the next five or ten years we’re going to see things like mobile phone screens that can heal themselves if they crack,” says Professor Wass.

The healing agent could also act as a warning of damage for maintenance engineers – the microspheres could also carry dyes to indicate damaged areas. “We’d probably do it with something that is invisible to the naked eye that you’d need to put an ultraviolet light on, because you don’t want an aeroplane wing with a big red splodge on it showing that is has been damaged,” laughs Wass.

As an aside, this artificial bruising reminds me of a finalist in the 2014 James Dyson Awards. The ‘Bruise’ team, from the Royal College of Art, had come up with a ‘smart’ suit which would artificially bruise when, for instance, an athlete had potentially harmed themselves. Not self-healing, I admit – but a useful indicator. Anyway, I digress.

One of the leaders in this field is Autonomic Materials

(http://www.autonomicmaterials.com/technology/) – founded some ten years ago by Dr Scot White at the University of Illinois. The company is looking to extend its current focus on self-healing coatings and expand into: adhesives, sealants, elastomers and structural components. Recently, by using a polymer, they managed to self-repair holes in plastic up to three centimetres in size!

And self-repair isn’t just about plastics and composites. Judging by the number of ‘hits’ on Inventricity, by far and away the most popular finalist in the European Inventor Award 2015 is Hendrik Marius Jonkers, and his self-healing Bioconcrete. It will be interesting to see how he fares in the popular vote when the winners are announced in Paris later this week. Of course, when it comes to self-healing concrete, we shouldn’t forget the pioneering bioremediation work done by Sookie Bang.

Finally, spare a thought for Nissan’s self-healing car paint. This was launched a couple of years ago. It doesn’t work by self-repair – if the paint is scratched through to the metal it stays scratched – but by deformation. When scratched the paint slowly ‘bounces’ back to its original position. I’ll leave you with their clever and amusing promotional video…