Two-dimensional observation of drainage and layering transitions in confined liquids

Articles you may be interested inA model of transluminal flow of an anti-HIV microbicide vehicle: Combined elastic squeezing and gravitational sliding Phys. Fluids 20, 083101 (2008); 10.1063/1.2973188Phenomenology of squeezing and sliding of molecularly thin Xe, CH 4 and C 16 H 34 lubrication films between smooth and rough curved solid surfaces with long-range elasticity Squeezing lubrication films: Layering transition for curved solid surfaces with long-range elasticityWe consider the dynamics of squeeze-out of a molecularly thin confined two-dimensional ͑2D͒ liquidlike layer. The squeeze-out is described by a generalized 2D Navier-Stokes equation which is solved exactly for the limiting case where the squeeze-out nucleates at the center of the contact area, and where the ͑perpendicular͒ three-dimensional pressure profile is Hertzian. We also present numerical results for the case where the nucleation is off-center. The theoretical results are in good agreement with recent experimental data by two of us for octamethylcyclotetrasiloxane. In light of our theoretical model calculations, we also discuss the spatially resolved diffusion experiments of Mukhopadhyay et al. ͓Phys. Rev. Lett. 89, 136103 ͑2002͔͒. Here, we obtain a puzzling disagreement between theory and experiment which requires more investigation.

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“…19 The transmitted intensity is converted to thickness using wellestablished techniques for the optical properties of multilayers. 27 FIG. 1.…”

Section: Resultsmentioning

confidence: 99%

Dynamics of squeeze-out: Theory and experiments

Zilberman

Becker

Mugele

et al. 2003

The Journal of Chemical Physics

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“…The mica sheets were silvered on their back sides and thus formed a Fabry-Pérot interferometer. The instrument was illuminated with monochromatic light, the wavelength of which was adjusted to the wing of one of the transmission peaks [10]. Using a video microscope, we recorded two-dimensional video images in transmission.…”

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“…Between the steps, the intensity is approximately constant. Using conventional numerical procedures for multilayer thin film interferometry [10,13], we converted the intensity to the thickness of the liquid layer. The reduction of film thickness in each step was found to be 0:95 0:1 nm.…”

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confidence: 99%

Nanofluidics: Viscous Dissipation in Layered Liquid Films

2003

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We studied the layer-by-layer collapse of molecularly thin films of a model lubricant confined between two atomically smooth substrates. The dynamics of the consecutive expulsion of four molecular layers were found to slow down with decreasing film thickness but showed no evidence for confinement-induced solidification. Using a hydrodynamic model, we show that the sliding friction of liquid layers on top of the solid substrates is approximately 18 times higher than the mutual friction between adjacent liquid layers. The latter was independent of film thickness and in close agreement with the bulk viscosity.

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“…Despite the dominance of the elastic energies in selecting the characteristic wavelength in the initial state of the instability, it is obvious that molecular interaction forces (such as the diverging disjoining pressure due to van der Waals energy and short-range adhesive forces) must play an important role in controlling the final shape. Approximate approaches to this problem are described in refs and . A true quantitative analysis, which is beyond the scope of this article, would require a variational minimization of the total elastic and molecular interaction energy as a function of the shape of the nanodrops under the constraint of constant volume.…”

Section: Modeling and Discussionmentioning

confidence: 99%

Instability of Confined Water Films between Elastic Surfaces

et al. 2009

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We investigated the dynamics of nanometer thin water films at controlled ambient humidity adsorbed onto two atomically smooth mica sheets upon rapidly bringing the surfaces into contact. Using a surface forces apparatus (SFA) in imaging mode, we found that the water films break up into a distribution of drops with a typical thickness of a few nanometers and a characteristic lateral size and spacing of several micrometers. Whereas the characteristic length is found to be independent of the ambient humidity, the characteristic time of the breakup decreases from approximately 1 to 0.01 s with increasing humidity. The existence of characteristic length and time scales shows that this breakup is controlled by an instability rather than a conventional nucleation and growth mechanism for SFA experiments. These findings cannot be explained by a dispersion-driven instability mechanism. In contrast, a model involving the elastic energies for the deformation of both the mica sheets and the underlying glue layer correctly reproduces the scaling of the characteristic length and time with humidity.

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Two-dimensional observation of drainage and layering transitions in confined liquids

Cited by 12 publications

References 19 publications

Dynamics of squeeze-out: Theory and experiments

Dynamics of squeeze-out: Theory and experiments

Nanofluidics: Viscous Dissipation in Layered Liquid Films

Instability of Confined Water Films between Elastic Surfaces

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