Surface relaxation of lyotropic lamellar phasesH. Bary-Soroker1 and H. Diamant2
1 School of Physics & Astronomy, Raymond & Beverly Sackler Faculty of Exact Sciences Tel Aviv University - Tel Aviv 69978, Israel
2 School of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences Tel Aviv University - Tel Aviv 69978, Israel
received 19 July 2005; accepted in final form 23 January 2006
published online 8 February 2006
We study the relaxation modes of an interface between a lyotropic lamellar phase and a gas or a simple liquid. The response is found to be qualitatively different from those of both simple liquids and single-component smectic-A liquid crystals. At low rates it is governed by a non-inertial, diffusive mode whose decay rate increases quadratically with wave number, . The coefficient A depends on the restoring forces of surface tension, compressibility and bending, while the dissipation is dominated by the so-called slip mechanism, i.e., relative motion of the two components of the phase parallel to the lamellae. This surface mode has a large penetration depth which, for sterically stabilised phases, is of order (dq2)-1, where d is the microscopic lamellar spacing.
61.30.St - Lyotropic phases.
68.03.Kn - Gas-liquid and vacuum-liquid interfaces: Dynamics (capillary waves).
82.70.Uv - Surfactants, micellar solutions, vesicles, lamellae, amphiphilic systems (hydrophilic and hydrophobic interactions).
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