Interfacial rheology

Although the concepts of surface viscosity and elasticity date back to the Belgian scientist Plateau in the 19th century, they have only later been formalized mathematically and subsequently been used in quantitative descriptions of surface flows. The concepts of surface viscosity and elasticity (Marangoni) effects are intimately related, and are not always distinguishable in an experimental setting. One such setting is the drainage of lamella in foams that we first investigated [1]. Another setting is the Landau-Levich-Derjaguin dip-coating flow, wherein a film of liquid is ‘deposited’ onto a solid substrate as it is withdrawn from a bath. This process is so fundamental to coating flows that it is ubiquitous in today’s coating technology. It is commonly assumed that, as for pure liquids, there is no thickening for liquids containing large amounts of soluble surfactants, i.e. the substrate withdrawal does not induce Marangoni stresses. However, in some cases thickening does occur, as demonstrated experimentally by collaborators at LPS, Orsay [3]. On the theoretical front, we have shown that thickening in the absence of Marangoni effects can be rationalized by surface viscosity [2].

[6] Champougny L., Scheid B., Restagno F., Vermant J. & Rio E., Surfactant-induced rigidity of interfaces: a unified approach to free and dip-coated filmsSoft Matter 11, 2758 (2015)
[5] Scheid B., Zawala J. & Dorbolo S., Gas dissolution in antibubble dynamics, Soft Matter 10, 7096 (2014)
[4] Scheid B., Dorbolo S., Arriaga L.R. & Rio E., Antibubbles dynamics: the drainage of an air film with viscous interfaces, Physical Review Letters 109, 264502 (2012)
[3] Delacotte J., Montel L., Restagno F., Scheid B., Dollet B., Stone H.A., Langevin D. & Rio E., Plate coating: influence of concentrated surfactants on the thickening, Langmuir 28, 3821 (2012)
[2] Scheid B., Delacotte J., Dollet B., Rio E., Restagno F., van Nierop E. A., Cantat I., Langevin D. & Stone H. A., The role of surface rheology in liquid film formation, Europhysics Letters 90, 24002 (2010)
[1] van Nierop E., Scheid B. & Stone H.A., On the thickness of soap films: An alternative to Frankel’s law, Journal of Fluid Mechanics 602, 119-127 (2008)  Corrigendum: Journal of Fluid Mechanics 630, 443-444 (2009)