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Soft Matter and Biological Physics


Eur. Phys. J. E 4, 337-341

Anomalous elasticity of an ordered lamellar liquid foam

J. Leng, F. Nallet and D. Roux

Centre de Recherche Paul-Pascal, CNRS, Avenue du Docteur Schweitzer, F-33600 Pessac, France

leng@ph.ed.ac.uk

(Received 7 August 2000)

Abstract
We investigate experimentally the linear viscoelastic properties of a lamellar liquid foam as a function of the cell size and spatial organisation. The system consists of multilamellar vesicles generated by a simple shear flow on a lyotropic lamellar phase. The vesicles can be prepared either in an amorphous or a spatially ordered state. Their size is easily tunable in the range R=0.5-$15 \mu$m. Whereas the shear modulus of the amorphous lamellar foam is alike that of usual liquid foams or concentrated emulsions and scales linearly with 1/R, the elastic modulus of the ordered foam is almost independent of the cell size. This result -probably the first describing the elasticity of an ordered foam-like system-remains unexplained.

PACS
62.20.Dc - Elasticity, elastic constants.
83.50.Fc - Linear viscoelasticity.
83.70.Jr - Liquid crystals; nematic, cholesteric, smectic, discotic, etc..


© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001