Wetting and evaporation of salt-water nanodroplets: A molecular dynamics investigation

Abstract

We employ molecular dynamics simulations to study the wetting and evaporation of salt-water nanodroplets on platinum surfaces. Our results show that the contact angle of the droplets increases with the salt concentration. To verify this, a second simulation system of a thin salt-water film on a platinum surface is used to calculate the various surface tensions. We find that both the solid-liquid and liquid-vapor surface tensions increase with salt concentration and as a result these cause an increase in the contact angle. However, the evaporation rate of salt-water droplets decreases as the salt concentration increases, due to the hydration of salt ions. When the water molecules have all evaporated from the droplet, two forms of salt crystals are deposited, clump and ringlike, depending on the solid-liquid interaction strength and the evaporation rate. To form salt crystals in a ring, it is crucial that there is a pinned stage in the evaporation process, during which salt ions can move from the center to the rim of the droplets. With a stronger solid-liquid interaction strength, a slower evaporation rate, and a higher salt concentration, a complete salt crystal ring can be deposited on the surface.

Formation, dissolution and properties of surface nanobubbles

“…We simulated the interfacial tension of the water-air interface of the nanobubbles at the atmospheric density and at the nanobubble density, which represent the surface tensions for bulk systems and for nanobubbles, respectively. The results reveal that the interfacial tension for the nanobubble case (50.7 ± 1.6 mN/m) is smaller than that for water-air interface at atmospheric conditions (57.6 ± 3.0 mN/m), where the latter value is in agreement with the model prediction from MD simulations [40,41]. The relatively smaller surface tension of nanobubbles than that in the equivalent system under atmospheric conditions indicates the strong effect of the gas phase.…”

Evaporative Crystallization in Drops on Superhydrophobic and Liquid-Impregnated Surfaces

“…32 Superhydrophobic surfaces reduce contact-line pinning and should force formation of condensed deposits, as has been observed for colloids (Figure 1B). 33 However, we hypothesize that the formation of crystals will alter this behavior.…”

Atomistic Molecular Dynamic Simulation of Dilute Poly(acrylic acid) Solution: Effects of Simulation Size Sensitivity and Ionic Strength

“…Molecular dynamics (MD) simulation, on the other hand, has proven to be a valuable tool to study the self-assembly of polymers at the microscopic level, which could reveal detailed three dimensional conformational and structural behaviour [40][41][42][43] . The physical structure and thermodynamics properties of NaCl in water have been abundantly investigated in prior investigations using both experimental and numerical methods [44][45][46][47][48][49][50][51] . For long-chained PAA, Reith et al 52 adopted a coarse-grained model and the results were supported by DLS data.…”