Disjoining Pressure of Water in Nanochannels

Abstract

Experiments of water wicking in 1D silicon-dioxide nanochannels of heights 59 nm, 87 nm, 124 nm and 1015 nm are used to estimate the disjoining pressure of water which was found to be as high as ~1.5 MPa while exponentially decreasing with increasing channel height. Such a relation resulting from curve fitting of experimentally-derived data was implemented and validated in computational fluid dynamics. This methodology integrates experimental nanoscale physics into continuum simulations thus enabling the numerical study of various phenomena where disjoining pressure plays an important role. Main TextA nanoscale thin liquid film on a surface can have significantly different properties than its bulk form [1]. At such short distances, intermolecular interactions with surface atoms can dominate and define new equilibrium positions/velocities of liquid atoms; as these fundamental parameters are statistically averaged to estimate thermodynamic properties [2], substantial changes in density, pressure, surface tension, viscosity, etc. can occur. Distances at which a surface can affect liquid properties depends on the atomic composition: if either atom is non-polar, the presence of only weak and short-range van der Waal's force limits such changes to <5 nm [3,4]; however, if both atoms are polar, strong and long-range electrostatic forces can alter properties up to tens to hundreds of nanometers from the surface [5][6][7]. The latter scenario often occurs in practical situations involving water on various surfaces.

Interplay of Local Heating, Nanoconfinement, and Tunable Liquid–Wall Interactions Drive Rapid Imbibition and Pronounced Mixing Between Two Immiscible Liquids

“…Some of these applications (as elucidated in great details in section S9 and Figure S19 In summary, in this Letter, we have used MD simulations to propose a unique energy-efficient setting that can promote imbibition and mixing between two immiscible liquids A and B: the liquids need to be confined in a nanochannel and subjected to local heating (at the interface or at other locations), and by subsequent tuning of the particle-A−wall and particle-B−wall interactions one can ensure either a strong imbibition or an enhanced mixing between these two liquids. Given the overwhelming need for energy-efficient manipulation and destruction of the stable interface formed by two immiscible liquids, the precise connection of the findings of the present study to several of such applications (in disciplines ranging from nanofluidic species separation and emulsion formation to improved nanofluidic oil recovery processes), and the potential of realizing the setup probed in our study experimentally (see ref 20), we anticipate that our findings will open up novel avenues for handling immiscible liquids with significant nanotechnological implications.…”

“…In a recent study, Zou et al 20 proposed an experimental system that considered localized heating of a nanofluidic system. In this study, 20 the authors wanted to measure the disjoining pressure of water in a nanochannel.…”

“…In a recent study, Zou et al 20 proposed an experimental system that considered localized heating of a nanofluidic system. In this study, 20 the authors wanted to measure the disjoining pressure of water in a nanochannel. For that purpose, they considered a nanochannel (of height 59 nm) completely filled with water at 300 K. Subsequently, they applied local heating (by imparting a constant heat flux at a specified spot on the nanochannel bottom surface by employing laser heating) in order to nucleate a bubble.…”

Mesoscopic Model for Disjoining Pressure Effects in Nanoscale Thin Liquid Films and Evaporating Extended Meniscuses

“…Wang et al conducted molecular dynamic simulation to assess the applicability of Hertz–Knudsen–Schrage relation in the presence of disjoining pressure. Zou et al determined the disjoining pressure of water by conducting wicking experiments in nanochannels with width ranging from 50 to 1000 nm.…”

Device‐Scale Nanochannel Evaporator for High Heat Flux Dissipation

“…The CA acquired from the meniscus image [18] or Young-Laplace equation [19] in the confined space may not be accurate because it is susceptible to errors in the detection of the three-phase contact line and the limitations associated with the camera/microscope field of view. Consequently, other studies have used the augmented Young-Laplace model, [25] interferometry, [26] and different contact angles for top and side walls of high-aspect-ratio wicks [27] to capture accurate apparent contact angle of fluid. In addition to the reliability of CA measurement, high interfacial heat flux is typically reported for wick distance of just a few microns, [18][19][20][28][29][30] however, such designs are prone to dry out and also may be limited for real-world applications.…”