Wenzel and Cassie-Baxter states of an electrolytic drop on charged surfaces

Abstract

In this paper, we provide a theory for the Wenzel and the Cassie-Baxter states of an electrolyte drop on charged surfaces. An electric double layer (EDL) develops when the electrolyte drop comes in contact with the charged surface. Therefore, the EDL free energy affects these states by triggering a hydrophilicity-inducing tendency. Consequently, an originally hydrophilic condition leads to a superhydrophilic Wenzel state, and an originally hydrophobic condition leads to a less hydrophobic Wenzel state. For the Cassie-Baxter state, this gives rise to the most remarkable situation of a hydrophilic (as compared to the original) Cassie-Baxter state.