Eur. Phys. J. E 8, 485-497 (2002)
DOI: 10.1140/epje/i2001-10109-4

The effect of shear flow on the Helfrich interaction in lyotropic lamellar systems

S.W. Marlow and P.D. Olmsted

Polymer IRC and Department of Physics & Astronomy, University of Leeds, Leeds LS2 9JT, UK

physwm@irc.leeds.ac.uk
p.d.olmsted@leeds.ac.uk

(Received 15 December 2001 and Received in final form 31 May 2002 Online publication 1 October 2002)

Abstract
We study the effect of shear flow on the entropic Helfrich interaction in lyotropic surfactant smectic fluids. Arguing that flow induces an effective anisotropic surface tension in bilayers due to a combination of intermonolayer friction, bilayer collisions and convection, we calculate the reduction in fluctuations and hence the renormalised change in effective compression modulus and steady-state layer spacing. We demonstrate that non-permeable or slowly permeating membranes can be susceptible to an undulatory instability of the Helfrich-Hurault type, and speculate that such an instability could be one source of a transition to multilamellar vesicles.

PACS
64.70.Md - Transitions in liquid crystals.
83.80.Qr - Surfactant and micellar systems, associated polymers.
87.16.Dg - Membranes, bilayers, and vesicles.


© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002