Multilayer liquid spreading on superhydrophilic nanostructured surfaces

Abstract

A phenomenon is presented where a propagating liquid on an array of nanopillars with scalloped features can separate into multiple layers of liquid films. The scallops were found to act as energy barriers that favor liquid separation into several layers over spreading in a uniform film. An analytical model based on surface energy was developed to explain the phenomenon. Additional tailored pillar geometries were fabricated and tested to validate the theory and model. The results provide design guidelines for geometries that promote multiple layer separation and offer opportunities to control liquid film thickness on superhydrophilic surfaces.