Shear-Induced States of Orientation of the Lamellar Phase of C12E4/Water

The shear-induced states of orientation of the lamellar lyotropic mesophase of tetraethylene glycol monododecyl ether (C 12 E 4 ) in water are investigated by polarizing microscopy, viscometry, small-angle light scattering, and deuteron NMR spectroscopy. The solution containing 40 w/w % surfactant shows a continuous transition from a state of aligned layers, whose normal is parallel to the velocity gradient, to a close packing of multilamellar vesicles (onion state). The size of the vesicles (diameter d ) is controlled by the shear rate γ̇, following the relationship d ∝ γ̇ a with a ≈ −0.5.