Discotic Micellar Nematic and Lamellar Phases under Shear Flow

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Abstract
Small-angle neutron scattering was employed to study the effect of shear flow on the nematic (N) and lamellar (Lα) phases in aqueous solutions of cesium perfluoro-octanoate. Shear rates as high as ~ 4000 s-1 were used. The N phase was found to align with the director in the direction of the gradient velocity. The Lα phase oriented with lamellae parallel to the shear plane. This change in equilibrium orientation is attributed, primarily, to changes in the value of the Ericksen viscosity parameter α2. Subtle shear-rate-dependent director reorientations were also observed in the proximity of the N-to-Lα phase transition.