Drop-Wise and Film-Wise Water Condensation Processes Occurring on Metallic Micro-Scaled Surfaces

TL;DR

This study compares water condensation mechanisms on superhydrophobic and superoleophobic micro-rough aluminum surfaces, revealing how surface chemistry influences whether condensation occurs via film-wise or drop-wise processes.

Contribution

It demonstrates that surface energy barriers determine the condensation pathway, with superoleophobic surfaces promoting drop-wise condensation due to higher Cassie-Wenzel state barriers.

Findings

Drop-wise condensation occurs on superoleophobic surfaces.

Film-wise condensation occurs on superhydrophobic surfaces.

Triple-stage droplet growth kinetics are observed on superoleophobic surfaces.

Abstract

Water condensation was studied on silanized (superhydrophobic) and fluorinated (superoleophobic) micro-rough aluminum surfaces of the same topography. Condensation on superhydrophobic surfaces occurred via film-wise mechanism, whereas on superoleophobic surfaces it was drop-wise. The difference in the pathways of condensation was attributed to the various energy barriers separating the Cassie and Wenzel wetting states on the investigated surfaces. The higher barriers inherent for superoleophobic surfaces promoted the drop-wise condensation. Triple-stage kinetics of growth of droplets condensed on superoleophobic surfaces is reported and discussed.