Treelike branched structures formed in dewetting thin films of a binary solution

Abstract

The authors present evidence for treelike patterns which developed during solvent evaporation from a phase separated bilayer resulting from a binary polymer solution spin coated onto a solid substrate. Initially, a bilayer structure containing a poly(isobutyl methacrylate) (BMA) solution layer on top of a nitrocellulose (NC) solution layer. During subsequent solvent evaporation, the top BMA solution layer becomes unstable and transforms into short ridges. Finally, solvent evaporation from the NC solution layer connects the BMA ridges to treelike patterns.