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New material shines under strain

Stretch material

The copper-infused polymer could provide early warning signs of material failure. 

24 January 2020

A new luminescent polymer developed by researchers at the Okinawa Institute of Science and Technology Graduate University, Japan, could enable engineers to pinpoint stresses on structures ranging from bridges to the frames of aircraft. 


The material is made by incorporating copper complexes into polybutylacrlate – a polymer used to synthesise paints, adhesives and sealants.


While materials that change when triggered by a mechanical force (known as mechanophores) are nothing new in themselves, this new polymer does not rely on stresses irreversibly breaking a weak chemical bond, as is the case with such materials when made from organic compounds.


The new material offers a lower stress threshold than mechanophores currently used, due to its greater sensitivity. It also benefits from being reversible. Currently, sensors using mechanophores can typically only be used once.

Video of polymer being stretched and released from OIST on Vimeo.

The material glows when exposed to UV light, but when it is stretched, the copper complexes glow more brightly. When the material is released from the stretched state, the light dims once again.


Key applications for the material could include stress-sensing acrylic paints to coat bridges, car frames or aircraft , which would offer early, targeted insights into points of stress long before the material fails.


Dr Ayumu Karimata, the first author of the study published in Chemical Communications, explained, ‘A stress-sensing paint would allow hotspots of stress on a material to be detected and could help prevent a structure from failing.’ 

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