Title: Molecular Dynamics Simulation Insight into Water Condensation as a Function of Surface Hydrophobicity

Biography:

Abstract

Water condensation plays a major role in a wide range of industrial applications. Over the past few years, many studies haveshown interest in designing surfaces with enhanced water condensation and removal properties; lotus leaf-like super-hydrophobic surfaces (SHS) and hydrophilic directional slippery rough surfaces (SRS) are some of the examples. To advance these designs a molecular scale understanding of the water behavior as a function of surface hydrophobicity is strongly needed. Since the approaches to quantify wetting at the macroscale do not always translate to the nanoscale, there is a need for new methods to characterize hydrophobicity at small scale. Using molecular dynamics computer simulations of well-characterized alkanethiol self-assembled monolayers with different head group chemistries, here we quantify the role of surface hydrophobicity on water condensation. We measured the water condensation rates on different surfaces and linked that behavior to well established surface characteristics to give a more complete picture of the role of surface hydrophobicity on the behavior of water. We showed that using our techniques, even small changes in the surface hydrophobicity are readily apparent. We also observed a remarkable correlation between our results and the role of surface hydrophobicity on the water compressibility, interfacial thermal conductance and contact angle when we compare data across different studies. Examining the total interaction energy between water and the surface, density fluctuations near the surface, the formation, growth mechanism and stability of water clusters, and the wetting process on thesurface we are able to provide insight into the water condensation process on different surfaces as a function of surface hydrophobicity.