Fall and rise of small droplets on rough hydrophobic substrates

Abstract

Liquid droplets on patterned hydrophobic substrates are typically observed either in the Wenzel or the Cassie state. Here we show that for droplets of comparable size to the roughness scale an additional local equilibrium state exists, where the droplet is immersed in the texture, but not yet contacts the bottom grooves. Upon evaporation, a droplet in this state enters the Cassie state, leading to a qualitatively new self-cleaning mechanism. The effect is of generic character and is expected to occur in any hydrophobic capillary wetting situation where a spherical liquid reservoir is involved.

6 pages, 6 figures, version as published in EPL

References in corpus (4)

• Modelling droplets on superhydrophobic surfaces: equilibrium states and transitions
• Spontaneous Breakdown of Superhydrophobicity
• The collapse transition on superhydrophobic surfaces
• Wetting gradient induced separation of emulsions: A combined experimental and lattice Boltzmann computer simulation study

Cited by in corpus (3)

• Efficient and accurate simulations of deformable particles immersed in a fluid using a combined immersed boundary lattice Boltzmann finite element method
• Parameter passing between Molecular Dynamics and continuum models for droplets on solid substrates - The static case
• Roughness gradient induced spontaneous motion of droplets on hydrophobic surfaces: A lattice Boltzmann study