How Solid–Liquid Adhesive Property Regulates Liquid Slippage on Solid Surfaces?

Abstract

The influence of solid-liquid adhesive property on liquid slippage at solid surfaces has been investigated using experiment approach on well-defined model surfaces as well as theoretical analysis. Based on a classical molecular-kinetic description for molecular and hydrodynamic slip, we propose a simple theoretical model that directly relates the liquid slip length to the liquid adhesive force on solid surfaces, which yields an exponential decay function. Well-defined smooth surfaces with varied surface wettability/adhesion are fabricated by forming self-assembled monolayers on gold with different mole ratios of hydrophobic and hydrophilic thiols. The adhesive force of a water droplet and the molecular slippage on these surfaces are probed by surface force apparatus and quartz crystal microbalance measurements, respectively. The experiment results are well consistent with our theoretical prediction. Our finding benefits the understanding of the underlying mechanism of liquid slippage on solid surfaces at molecular level and the rational design of microfluidics with an aim to be frictionless or highly controllable.

Relation between boundary slip mechanisms and waterlike fluid behavior

“…Even though the no-slip boundary condition is good to describe confinement up to microchannels [24][25][26][27][28], this might not be the case for nanoconfined geometries [29][30][31][32]. Different slip condition mechanisms might occur as the relative velocity between the fluid and the wall is changed.…”

“…Confined water in microchannels presents a slip length of the order of nanometers [24][25][26][27][28] and therefore no-slip boundary conditions are not applicable. As the channel size decreases, the water mobility increases [29][30][31][32].…”

Effect of critical thickness on nanoconfined water fluidity: review, communication, and inspiration

“…This is because the molecular dynamic simulation is able to build any ideal water-wall system, which is easy to avoid a lot of uncontrollable factors (e.g., smoothness of wall, adsorbed gases on walls or any other unknown contaminants) (Wu et al 2017). As a result, the deviations of the simulated results from experiments are relatively large (Ortiz-Young et al 2013;Wu et al 2017;Xue et al 2014;Bouzigues et al 2008;Cottin-Bizonne et al 2008Maali et al 2008;Honig and Ducker 2007;Joly et al 2006;Cho et al 2004;Vinogradova et al 2001;Ahmad et al 2015).…”

Boundary conditions with adjustable slip length for the lattice Boltzmann simulation of liquid flow

“…One of ways to reduce friction 40 is to make use of superhydrophobic surfaces [3,4,5]. The development of the chemical science engineering makes it possible to obtain superhydrophobic surfaces with special chemical properties and microstructures [6,7,8,9]. Superhydrophobic surfaces possess numerous micro-grooves, which entrap air when the surfaces are fully submerged in liquid [10,11].…”

“…Firstly, we analyse three half-way schemes: Eqs. (8), (9) and (10). Wang et al [36] adopted the Couette flow with linear velocity gradient to deduce the relation between the combination parameters of BSR scheme with the 295 slip length.…”