Deviation from Self-Similarity in Droplets on Soft Solids

Droplets on rigid solids or liquid substrates adopt self-similar shapes with constant interface curvature, dictated by interfacial tension. In contrast, droplets on soft solids deviate from this constant-curvature geometry as interfacial tension couples to elasticity, pulling up the substrate to form a capillary ridge. Here, we dewet thin polystyrene films onto poly(dimethylsiloxane) substrates and find that, unlike droplets on rigid or liquid substrates, the geometry of droplets on soft solids is not self-similar across sizes.