SHEAR ORIENTATION OF LYOTROPIC HEXAGONAL PHASES

The shear orientation of the hexagonal liquid crystal phase of nonioni c surfactant/water mixtures was investigated by means of different tec hniques, namely, microscopy, small-angle light and neutron scattering, (SALS, SANS), birefringence, and nuclear magnetic resonance (NMR). On a microscopic length scale probed by NMR, SANS, and birefringence, th e shear flow results in an alignment of rodlike micelles along the flo w direction. The 10 plane was parallel to the shear plane. On a mesosc opic length scale, studied by microscopy and SALS, a stripe texture wa s observed. This is due to an undulation of the director which is on a verage aligned in flow direction. The corresponding SALS pattern shows a better orientation correlation perpendicular to the flow direction.