Squeezing out opal-like colours by the mile

Researchers have devised a new method for stacking microscopic marbles into regular layers, producing intriguing materials which scatter light into intense colours, and which change colour when twisted or stretched.

 

Finding a way to coax objects a billionth of a metre across into perfect formation over kilometre scales is a miracle.
  -  Jeremy Baumberg

The team, led by the University of Cambridge, has invented a way to make such sheets on industrial scales, opening up applications ranging from smart clothing for people or buildings, to banknote security.

Using a new method called Bend-Induced-Oscillatory-Shearing (BIOS), the researchers are now able to produce hundreds of metres of these materials, known as ‘polymer opals’, on a roll-to-roll process. The results are reported in the journal Nature Communications.

Some of the brightest colours in nature can be found in opal gemstones, butterfly wings and beetles. These materials get their colour not from dyes or pigments, but from the systematically-ordered microstructures they contain.

The team behind the current research, based at Cambridge’s Cavendish Laboratory, have been working on methods of artificially recreating this ‘structural colour’ for several years, but to date, it has been difficult to make these materials using techniques that are cheap enough to allow their widespread use.


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Image: Polymer Opals
Credit: Nick Saffell


Reproduced courtesy of the University of Cambridge
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