Complexity in Wetting Dynamics

Abstract

The spreading dynamics of a droplet of pure liquid deposited on a rigid, nonsoluble substrate has been extensively investigated. In a purely hydrodynamic description, the dynamics of the contact line is determined by a balance between the energy associated with the capillary driving force and the energy dissipated by the viscous shear in the liquid. This balance is expressed by the Cox-Voinov law, which relates the spreading velocity to the contact angle. More recently, complex situations have been examined in which dissipation and/or the driving force may be strongly modified, leading to sometimes spectacular changes in wetting dynamics. We review recent examples of effects at the origin of deviations from the hydrodynamic model, which may involve physical or chemical modifications of the substrate or of the wetting liquid, occurring at scales ranging from the molecular to the mesoscopic.

Surface Activity, Wettability, and Aggregation Behavior of Ecofriendly Fluorocarbon Surfactant Based on Double Perfluorinated Branched Short Chains

“…According to Young’s equation and as mentioned above, the solid–liquid interfacial tension of SFDC should be significantly smaller than that of SFDC-L. It is generally accepted by current researchers that the solid–liquid interfacial tension tends to be smaller when the liquid phase exhibits superior wettability on the surface of the solid. − Therefore, we conclude that SFDC has better wettability than SFDC-L for the PTFE materials.…”

Wetting on silicone surfaces

“…, the drop footprint); however, the dissipation in the wetting ridge is the dominant source of sliding friction. 75,84–86 Hence, to quantify the sliding friction, it is sufficient to only focus on the wetting ridge.…”

“…On elastomeric surfaces, the wetting ridge dissipation is more complex. 66,74,86,223 Dissipation in elastomers is non-Newtonian and depends on the (oscillatory) strain rate ω . The crosslinks add (visco)elasticity to the material fabric.…”

“…46,78–83 Contact friction mostly dissipates in the ridge. 74,75,84–86 Therefore it is critical for lubrication and drop sliding. However, it also accumulates surface material, and contacting objects may entrain surface material in the wetting ridge.…”