'Chameleon' crystals allow for colour-changing clothes, cars

Researchers have developed a new method of controlling crystals using light and chemistry that could make clothing or cars change colour on demand.
University of Michigan researchers developed the method which involves shining a laser on tiny latex particles to make them assume a 3D crystalline shape or pattern, such as a letter M.
When the laser is switched on or off, the crystals appear or disappear.
"Unlike for chameleons or octopuses, creating man-made materials that change colour on demand is really difficult," said Mike Solomon, a chemical engineer at the University of Michigan in Ann Arbor and senior researcher of the study.

"Wouldn't it be neat if you could change some attribute - such as a display, part of car, or clothing - on demand?" Solomon told 'LiveScience'.
Solomon and his graduate student, Youngri Kim, found a way to achieve shape- and colour-changing effects using latex paint microparticles - tiny particles about 0.001 millimetres in diameter - in a kerosene-like fluid, by shining a laser on them.

By manipulating these "camouflage crystals," the researchers were able to construct a letter "M," for the University of Michigan. They have also experimented with making optical lenses.
"We can shine the light in a certain region, and the particles create a crystalline region where they all come together and create this crystal structure," Kim said.

The new method of making materials change their shape or colour has many exciting applications. For instance, it could be integrated into clothing or automobile paint, for camouflage purposes, or just for aesthetic reasons.
The research will be published in the journal Nature Communications.