Anomalous elasticity of an ordered lamellar liquid foam
نویسندگان
چکیده
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 μm. 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.
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