Designer colours

Military clothing that changes colour to warn of chemical attack, or food packaging that shifts in tone to indicate just how long it has been on the shelf are just two of the applications for a technology currently under development in the UK.

Researchers are producing materials with bright, vibrant colours that are created through the manipulation of nanoparticles rather than using harmful toxic dyes, which are of increasing concern for their impact on the environment.

This new flexible plastic material could be designed to degrade safely over time and could have numerous applications in mobile electronics, fashion and automotive industries.

The new technique manipulates tiny polymer spheres which refract light in certain ways depending on how they are stacked together. Each of the spheres is only about around 200nm wide, or roughly the same size as the wavelength of light.

When light strikes them it is reflected around inside the structure, in much the same way that opals reflect light, according to lead researcher, Prof Jeremy Baumberg, head of the quantum, light and matter group in the Department of Physics at