Wetting Behavior of Water near Nonpolar Surfaces

Abstract

We use molecular simulation to study the wetting behavior of water near flat nonpolar surfaces. The interface potential approach is used to capture the evolution of various interfacial properties over a broad range of temperature and substrate strength. Three model substrates are considered: an atomistically detailed face-centered cubic (FCC) lattice, a graphite lattice, and a structureless wall. We first examine the evolution of the contact angle with substrate strength for conditions ranging from near drying to complete wetting at select temperatures. A notable characteristic of all systems is the presence of a surface strength at which the contact angle is independent of temperature. We also identify an analogous point in which the quantity γ lv cos θ is temperature invariant. We discuss the relationship between this point and the excess entropy of the solid−liquid interface. We next consider the temperature dependence of interfacial properties. We find the contact angle to decrease with temperature at relatively strong surfaces and increase with the temperature at relatively weak surfaces. The work of adhesion is found to be a useful quantity for describing the interfacial properties of water. The enthalpic and the entropic contributions to the work of adhesion are obtained from its temperature dependence. These properties are found to be directly related to the affinity of water for a solid surface and therefore serve as useful measures of the hydrophobicity of a surface. Finally, we examine the effect of surface strength and temperature on the density depletion associated with water at hydrophobic surfaces. We study various metrics that quantify the density and compressibility of water in the vicinity of hydrophobic surfaces. Comparisons are drawn between the behavior of water and simple nonpolar fluids at solvophobic surfaces.

Dry-Surface Simulation Method for the Determination of the Work of Adhesion of Solid–Liquid Interfaces

“…[8][9] Kumar and Errington recently provided an overview of the numerous works that have been carried out to address this question. 10 These authors concluded that "the enthalpic and the entropic contributions to the work of adhesion [...] are found to be directly related to the affinity of water for a solid surface and therefore serve as useful measures of the hydrophobicity of a surface", thus illustrating the key role of quantities such as W adh or W SL .…”

“…10,[25][26] The test-area method was introduced to calculate γ LV 27 and was extended to the calculation of γ SL in Lennard-Jones systems. 28 We have introduced the phantom-wall method based on thermodynamic integration to obtain W SL .…”

Understanding the influence of Coulomb and dispersion interactions on the wetting behavior of ionic liquids

“…Similar wetting behavior has also been observed in the recent Monte Carlo simulation studies performed within our group involving the Lennard-Jones fluid 2 and water. 16,17 In this work, we show how the strength of Coulombic interactions influence the temperature dependence of contact angles over a range of substrate-fluid interaction strengths.…”

“…The trends noted above for cos θ have also been reported in previous theoretical and computational studies featuring the LJ fluid 2, 13-15, 44 and water. 16,17 We now explore how the characteristics of these isotherms are related to the nature of the fluid-fluid interaction and temperature. It is noted that the value of ε wf at which the contact angle is effectively independent of temperature increases with increasing α.…”

Magnetically separable g‐C3N4 hybrid nanocomposite: Highly efficient and eco‐friendly recyclable catalyst for one‐pot synthesis of α‐aminonitriles

“…[5] Two-dimensional g-C 3 N 4 , which is the most stable allotrope of carbon nitride, is of great interest to the catalytic community owing to its unique properties derived from the quantum confinement effect in the plane. [6][7][8][9][10] Due to its special physical and chemical properties, nontoxicity, excellent chemical stability and unique optical and electronic properties, it has attracted widespread attention for various applications such as materials science, environmental remediation photovoltaic solar cells, chemical sensors and photocatalysis. [11][12][13] Furthermore, g-C 3 N 4 can be easily prepared on a large scale via the hydrothermal method without any organic solvents from low-cost materials such as melamine or urea derivatives and it is insoluble in most solvents.…”