Superhydrophobic surfaces with hierarchical structure

The physics related to superhydrophobic surfaces has been investigated with attention of its potential applications in a variety of industrial and research fields. In the present study, we report a facile method for preparing superhydrophobic surfaces based on micro and nano scaled structures. Composite thin films are formed by using SiO2 nanoparticles and poly(dimethylsiloxane) (PDMS). The static contact angle, advancing contact angle, and receding contact angle are measured to investigate the surfaces' water repelling property. The formed SiO2-PDMS composite films, with different nanoparticle concentrations and sizes, can render the surfaces with superhydrophobicicty, exhibiting large contact angles and small contact angle hysteresis. The composite films are observed by using the Scanning Electron Microscope (SEM). It is demonstrated that the hierarchical structure in micro and nano scale on the surface, plays an important role in prompting the superhydrophobic (water-repelling) properties. Wetting phenomena and related theories are also discussed within the paper.

Research highlights
► We prepare superhydrophobic surfaces based on SiO2 nanoparticles and PDMS.
► We examine the surfaces’ water repelling properties and micro & nano-structure.
► Increasing the nanoparticle concentration will enhance the water repelling effect.
► The hierarchical structure is formed and provides the multilayer of roughness.
► The formed surface structure prompts superhydrophobicity.