Elastomer-immobilized tunable colloidal photonic crystal films with high optical qualities and high maximum strain

High-quality elastomer-immobilized colloidal crystal films with low particle volume fractions can be prepared using hydrogel-immobilized single-crystalline colloidal crystal films processed by shear flow. The solvent-free elastomer film demonstrated a full-colour change from red to blue with high uniformity over a cm2 scale, achieved by varying the mole fraction of monomers in the hydrogel. Owing to the low particle volume fraction, the elastomer film exhibited a colour change from red to blue upon stretching, and the maximum strain reached 120%. The film provided reversible and repeatable colour changes during extension without residual strain. The prepared films have the potential to be used in simple strain sensors to express invisible strains through colour change.