Elastic polymer mimics opaline light reflection

Discovery News : Opals get their color from the diffraction of light hitting their internal structures, not from any inherent pigmentation. The stones form when spheres of silica coalesce into compact layers as water evaporates, and the resulting structures can produce a wide range of colors. An international collaboration has created an elastic polymer that duplicates that structure using nanoparticles wrapped in rubbery shells. The shells bond the nanoparticles together and produce a sheet that reflects different wavelengths of light as it is stretched and the distance between the particles changes. The colors produced also depend on the size of the nanoparticles used. The material presents possible application as a mechanical strain detector or as a nontoxic and colorfast replacement for dyes. It could also be a cheaper replacement for anticounterfeiting holograms in money.