Hierarchical wrinkling on elastomeric Janus spheres

Abstract

Hierarchical wrinkling on elastomeric Janus spheres is permanently imprinted by swelling, for different lengths of time, followed by drying the particles in an appropriate solvent. First-order buckling with a spatial periodicity (λ₁₁) of the order of a few microns and hierarchical structures comprising of 2^nd order buckling with a spatial periodicity (λ₁₂) of the order of hundreds of nanometers have been obtained. The 2^nd order buckling features result from a Grinfeld surface instability due to the diffusion of the solvent and the presence of sol molecules.