Consumer goods, from laptops to cars, could one day be coated in a new plastic with self-healing capabilities.
You’re late for the meeting, running up the concrete stairs two steps at a time. Then you slip, drop your new shiny laptop – and look with horror at the hairline crack in the lid. It’s almost impossible to get these things repaired and you know IT won’t just give you a new one…
Well, don’t worry. Just shine a light on it and watch the crack disappear.
It’s a nice idea, isn’t it? The thought that plastic could heal itself, just like a person. Now, a new material has been developed by Professor Marek Urban, of the University of Southern Mississippi, that does just that; mimicking skin by ‘healing’ its own surface.
It works like this. The plastic contains long chains of small molecular bonds, or ‘bridges,’ that are severed when the material is damaged. Breaking certain copolymer (a mixture of different monomer units) bonds in these chains results in changes that cause the affected area to turn red or ‘bleed’, so that the defect can be located.
When exposed to external stimuli such as specific frequencies of light, or a change in pH or temperature, there is sufficient energy for the bonds to reform, repairing the plastic and causing the red colouring to disappear – signalling that the damage is fixed. This can be done manually (by simply applying the right wavelength light to the damage for example) or even by natural effects, such as sunlight or the temperature of the plastic’s surroundings.
The developers hope the material can be used in consumer goods such as laptops, mobile phones and cars, which would save money and resources, and increase the quantity of recyclable plastic. It’s the latest development in a growing trend for self-healing materials, which are already appearing in sectors such as aerospace engineering or architecture.
Further development is required however, to ensure the plastic can be used efficiently, says Sam Neuser, who is specialising in the study of self-healing materials at the École Polytechnique Fédérale de Lausanne. “In many cases, it will remain easier – and cheaper – to replace a damaged part than invest in a self-repairing version”, he says. “One should also not forget the trade-off in weight which comes with many self-repair systems”. In other words, the more robust the piece of kit, the heavier it will be.
He suggests that “self-healing materials will first only be found in very specific, high value applications”, but adds that Urban’s research could help accelerate their application to the broader market. – Edwin Colyer