Europhys. Lett.
Volume 66, Number 6, June 2004
Page(s) 888 - 894
Section Interdisciplinary physics and related areas of science and technology
Published online 01 June 2004
Europhys. Lett., 66 (6) , pp. 888-894 (2004)
DOI: 10.1209/epl/i2003-10260-6

Equilibrium onions?

L. Ramos1, D. Roux2, P. D. Olmsted3 and M. E. Cates4

1  Groupe de Dynamique des Phases Condensées (UMR CNRS-UM2 5581), CC26 Université Montpellier 2 - 34095 Montpellier Cedex 5, France
2  Centre de Recherche Paul Pascal - avenue Schweitzer, 33600 Pessac, France
3  Department of Physics and Astronomy & Polymer IRC, University of Leeds Leeds LS2 9JT, UK
4  School of Physics, University of Edinburgh, JCMB Kings Buildings Mayfield Road, Edinburgh EH9 3JZ, UK

(Received 30 July 2003; accepted in final form 15 April 2004)

We demonstrate the possibility of a stable equilibrium multi-lamellar ("onion") phase in pure lamellar systems (no excess solvent) due to a sufficiently negative Gaussian curvature modulus. The onion phase is stabilized by non-linear elastic moduli coupled to a polydisperse size distribution (Apollonian packing) to allow space-filling without appreciable elastic distortion. This model is compared to experiments on copolymer-decorated lamellar surfactant systems, with reasonable qualitative agreement.

82.70.Uv - Surfactants, micellar solutions, vesicles, lamellae, amphiphilic systems (hydrophilic and hydrophobic interactions).
68.18.Jk - Surface and interfaces; thin films and low-dimensional systems (structures and nonelectric properties): Phase transitions.
61.30.St - Lyotropic phases.

© EDP Sciences 2004