Scientists from the University of Sheffield in the UK have developed intensely coloured polymer materials that do not use pigments, but instead achieve coloration by creating highly ordered layers from a block copolymer. The scientists think the materials could be used to create anti-counterfeit devices on passports or banknotes due to the difficulty in copying. In nature, coloration is often achieved through structure, not pigment, for example in beetle shells and butterfly wings. Dr Andrew Parnell, from the University of Sheffield's Department of Physics and Astronomy, said: “Our aim was to mimic the wonderful and funky coloured patterns found in nature, such as peacock feathers. We now have a painter's palette of colours that we can choose from using just two polymers to do this. We think that these materials have huge potential to be used commercially.” Parnell told European Plastics News that the research work has involved a polystyrene-polyisoprene block copolymer. This was chosen because the component materials are relatively inexpensive and block copolymers are already produced in large quantities for thermoplastic elastomers. The blending of the block copolymer results in the material self-assembling into a lamellar structure, causing optical effects similar to opals. The colour also changes depending on the viewing angle. By blending the polymers in different quantities, a range of colours can be produced. Parnell said commercialisation will require adaptation of the material for a particular processing route, like ink jet printing or slot die printing. The researchers have received approaches from a number of potential commercial partners wanting to assess the material. As well as bank notes and passports, mass produced products may benefit from the technique in the future. Developing more hierarchical structures in the materials would enhance their effectiveness as security markers, said Parnell. The researchers are now experimenting with shear and rheology to understand how to manipulate the materials.