Experimental Characterization of Water Condensation Processes on Self-Assembled Monolayers Using a Quartz Crystal Microbalance with Energy Dissipation Monitoring

Water condensation on solid surfaces is a universal phenomenon that plays an essential role in many interfacial phenomena, such as friction, corrosion, adsorption, etc. Thus far, the initial states of water condensation on surfaces with varying chemical properties have yet to be fully explained at the nanoscale. In this study, we performed a real-time characterization of water condensation on self-assembled monolayers (SAMs) with different functional groups using quartz crystal microbalance with energy dissipation monitoring (QCM-D). We found that the kinetics of water condensatison is critically dependent on the head group chemistries. We discovered that the condensed water’s viscoelasticity cannot be predicted from macroscopic water contact angles, but they were shown to be consistent with the predictions of molecular simulations instead. In addition, we also found a highly viscous interfacial water layer on hydrophilic protein-resistant SAMs. In contrast, the interfacial water layer/droplet on either hydrophilic protein-adsorbing or hydrophobic SAMs exhibited lower viscosity. Combining our and previous findings, we discuss the influence of interfacial hydration on the viscoelasticity of condensed water.