Diffusion-Controlled, Self-Organized Growth of Symmetric Wrinkling Patterns

Symmetric instability patterns in the UV-ozone crosslinked surface of a polystyrene film grow radially outward from local defect sites in the presence of solvent vapor. The diffusion kinetics of the solvent governs the pattern morphology by establishing stress fields that favor the orientation of wrinkles in a dendritic-like spoke pattern (left) or in a target pattern consisting of concentric rings (right).