8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P6.32Fri 911:10-14:00Surfactant-assisted spreading of an emulsion on a liquidbathMatthieu Roché, 1 Zhenzhen Li, 2 Ian Griffiths, 2 Arnaud Saint-Jalmes, 3 and HowardA. Stone 21 Princeton University, G02 E-quad, Olden Street 08544, Princeton, USA2 rinceton University, G02 E-quad, Olden Street 08544, Princeton, USA3 Institut de Physique de Rennes, Rennes, FranceWe studied experimentally the spreading dynamics of a drop of a surfactant-stabilized oil-in-wateremulsion on pure water. After deposition, oil droplets of the emulsion spread at the air/water interfacebecause of a Marangoni flow due to the difference in surface tension between the emulsionand water. The oil droplets eventually stop, forming a ring whose diameter is constant as long asoil droplets are transported. When the initial drop empties, the ring collapses, a phenomenon notyet reported experimentally to our knowledge. Spreading and collapse occur on a few hundredmilliseconds while the ring stage lasts a few seconds. We show that these dynamics result of theout-of-equilibrium surfactant desorption from the surface of the layer. We also bring evidence thatthe surface of the layer is deformed during spreading with a jump in the layer thickness at thelocation of the ring.32