Fast relaxation of a hexagonal Poiseuille shear-induced near-surface phasein a threadlike micellar solution

The dynamics of near-surface conformations in complex fluids under flow sho uld dramatically affect their rheological properties. We have made the firs t measurements resolving the decay kinetics of a hexagonal phase induced in a threadlike polyionic micellar system under Poiseuille shear near a quart z surface. Upon cessation of shearing flow, this minimum interference cryst alline phase formed within similar to 20 mu m of the surface "melts" to a m etastable two-dimensional liquid of aligned micelles in similar to 0.7 s. T his is some three orders of magnitude shorter than the time required for bu lk (Couette) shear-aligned micelles in this system to reach a fully entangl ed state. [S1063-651X(99)50808-8].