Abstract: New photonic properties are produced in materials which are assembled from diverse combinations of metals, semiconductors and dielectrics that are periodically structured on the 100nm-scale, with a wealth of potential applications ranging from communications to bio-sensing. However producing such nanomaterials on the mass-scale is far from trivial as three-dimensional structures are very hard for traditional lithography, and self-assembly has to date been a lab-scale tricky process.
Here we concentrate on a new range of structural colour nanomaterials which can be mass produced as films on the kilometre scale. While most man-made (and natural) colours exploit dye absorption, there is strong interest in avoiding these carcinogenic and UV-bleached chemicals. Alternative structural colours are produced from periodic wavelength-scale-sized transparent components, and thus are benign, long-lived, and possess new optical features. We create polymer photonics crystals made of cross-linked polymer spheres dispersed in a soft elastomeric matrix, using a novel industrially-scalable shear-based nano-assembly. Simply tuning the size of the spheres changes the colour across the entire visible spectrum, while optimised shearing creates single-domain opal films. Stretching these unusual elastomeric photonic crystals breaks their traditional optical scattering selection rules, and enables many applications. We demonstrate a wide variety of new optical properties based on the resonant scattering phenomena.
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