Dual Marangoni effects and detection of traces of surfactants

In an article recently published in Soft Matter Journal, we report controlled and tunable Marangoni flows resulting from concentration gradients that are induced by placing a droplet of volatile solute above the surface of a liquid. Condensation of the solute at the liquid surface results in a surface tension gradient that drives a permanent flow of surface velocity up to a few centimenters per second. Depending on the sign of the variation of surface tension with solute concentration, inward or outward surface flows can be obtained. We show that, in the region close to the vertical axis of the droplet, the flow rate varies with the droplet heigth following a power law, whose exponent depends on the nature of the transfer of the solute in air. In the case of a purely diffusive transfer we establish an analytical law for the velocity rate, which is in very good agreement with the experimental data. In addition, we discuss the effect of convection on the found scaling laws. Finally, we demonstrate that the Marangoni flow is modified by the addition of a very small quantity of surfactants, which themselves induce a Marangoni flow opposing the primary one. We suggest it could provide a simple method to detect traces of surfactants, of increasing sensitivity with decreasing surfactant solubility.

Link to the Soft Matter Journal

Haut de page



À lire aussi...

Le frottement des caoutchoucs dépend de leur déformation

Dans un article récemment paru dans Soft Matter, nous montrons que le frottement local d’élastomères silicones sur des surfaces lisses de verre est (...) 

> Lire la suite...

Foaming of transient polymer hydrogels

Foams made with complex fluids enables to obtain a very good foam stability, however such foams are usually difficult to produce and process : (...) 

> Lire la suite...

 

Informations Pratiques

Sciences et Ingénierie de la Matière Molle - UMR 7615

10 rue Vauquelin
75231 PARIS CEDEX 05

  • Directeur : E. Barthel
  • Directeur adjoint : J.B. d’Espinose
  • Directrice adjointe : G. Ducouret
  • Pôle gestion : F. Decuq, M.-T. Mendy et M. Hirano-Courcot
  • Communication : A. Hakopian et M. Ciccotti
  • Systèmes d’information : A. Hakopian
  • Assistant prévention : F. Martin

Comment venir ?