Surface tension profiles in vertical soap films

Adami, Nicolas; Caps, Hervé

doi:10.1103/physreve.91.013007

Cited by 11 publications

(9 citation statements)

References 25 publications

(88 reference statements)

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“…Combining the present study to the recent predictions by Saulnier et al 46 for surface tension gradients in the upper nonstationary part of soap lms, it is now possible to forecast the surface tension difference across the whole lm. For a C 12 E 6 solution at 3 cmc and Ca z 6 Â 10 À5 , this total surface tension difference is found of the order of 1 mN m À1 , which is small compared to the surface tension of usual surfactant solutions, but well in line with recent experimental work on surface tension gradients in soap lms by Caps et al 47…”

Section: Surface Tension Gradientsupporting

confidence: 89%

Surfactant-induced rigidity of interfaces: a unified approach to free and dip-coated films

et al. 2015

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The behavior of thin liquid films is known to be strongly affected by the presence of surfactants at the interfaces. The detailed mechanism by which the latter enhance film stability is still a matter of debate, in particular concerning the influence of surface elastic effects on the hydrodynamic boundary condition at the liquid/air interfaces. In the present work, "twin" hydrodynamic models neglecting surfactant transport to the interfaces are proposed to describe the coating of films onto a solid plate (LandauLevich-Derjaguin configuration) as well as soap film pulling (Frankel configuration). Experimental data on the entrained film thickness in both configurations can be fitted very well using a single value of the surface elasticity, which is in good agreement with independent measurements by mean of surface expansion experiments in a Langmuir through. The analysis shows how and when the soap films or dip coating experiments may be used to precisely and sensitively measure the surface elasticity of surfactant solutions.

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Section: Surface Tension Gradientsupporting

confidence: 89%

Surfactant-induced rigidity of interfaces: a unified approach to free and dip-coated films

et al. 2015

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“…This remains to be understood but is supported by recent papers on Frankel's experiment predicting a very small value of Dg along the lm. [41][42][43]…”

Section: Discussionmentioning

confidence: 99%

A study of generation and rupture of soap films

et al. 2014

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What are the lifetime and maximum length of a soap film pulled at a velocity V out of a bath of soapy solution? This is the question we explore in this article by performing systematic film rupture experiments. We show that the lifetime and maximal length of the films are fairly reproducible and controlled only by hydrodynamics. For surfactants with high surface elastic modulus, we argue that the rupture is triggered by the expansion of a thinning zone at the top of the film. The length ltz of this zone expands with time at a velocity equal to V/2, which can be obtained by a balance between gravity and viscous forces. The film lifetime is then found to decrease with the pulling velocity V, which implies that the surface tension gradient along the film increases with V. This surface tension gradient is found to be surprisingly small. Finally, the lifetime of films stabilised by solutions with small surface elastic modulus turns out to be much shorter than the ones for films with rigid interfaces.

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“…The prediction of the velocity field, taking into account this interface extension, would require an experimental determination of the coupling between the film extension and the dynamical surface tension. This is still an experimental challenge [14,20]. However, we believe that a model based on the original assumption of Mysels et al of an inextensible interface, as the one developped below, may capture a large part of the physics.…”

Section: Fig 1 Sketch Of Our Experimental Setupmentioning

confidence: 96%

Velocity Field in a Vertical Foam Film

et al. 2017

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The drainage of vertical foam films governs their lifetime. For a foam film supported on a rectangular solid frame, when the interface presents a low resistance to shear, the drainage dynamics involves a complex flow pattern at the film scale, leading to a drainage time proportional to the frame width. Using an original velocimetry technique, based on fluorescent foam films and photobleaching, we measure the horizontal and vertical components of the velocity in a draining film, thus providing the first quantitative experimental evidence of this flow pattern. Upward velocities up to 10 cm/s are measured close to the lateral menisci, whereas a slower velocity field is obtained in the center of the film, with comparable downwards and horizontal components. Scaling laws are proposed for all characteristic velocities, coupling gravitational effects, and capillary suction.

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Surface tension profiles in vertical soap films

Cited by 11 publications

References 25 publications

Surfactant-induced rigidity of interfaces: a unified approach to free and dip-coated films

Surfactant-induced rigidity of interfaces: a unified approach to free and dip-coated films

A study of generation and rupture of soap films

Velocity Field in a Vertical Foam Film

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