Numerical and experimental investigation of static wetting morphologies of aqueous drops on lubricated slippery surfaces using a quasi-static approach

The static wetting behavior of drops on surfaces with thin lubricating films is very different compared to solid surfaces. Due to the slow dynamics of the wetting ridge, it is challenging to predict the apparent contact angles of such drops. It is hypothesized that for a sinking drop on a lubricated surface, quasi-static wetting morphology can be numerically computed from the knowledge of interfacial energies, lubricant thickness, and drop volume. In this study, we use Surface Evolver to numerically compute the static wetting morphology for the four-phase system using a quasi-static approach with a sinking time similar to the early-intermediate times, and the results agree well with the corresponding experiments. We find that the apparent contact angles depend significantly on the lubricant thickness and substrate wettability compared to other parameters.

Automated summary

The static wetting behavior of drops on surfaces with thin lubricating films is different from that on solid surfaces. It is difficult to predict the apparent contact angles of such drops due to the slow dynamics of the wetting ridge. In this study, the quasi-static wetting morphology of sinking drops on lubricated surfaces is numerically computed using Surface Evolver, and the results agree well with experiments. The apparent contact angles are found to be significantly influenced by the lubricant thickness and substrate wettability compared to other parameters.