PERIODIC TEXTURES OF NEMATIC POLYMERS AND ORIENTATIONAL SLIP

Nonlinear numerical analysis predicts that when a uniformly oriented nematic polymer, placed between parallel isotropic untreated surfaces, is subjected to a sufficiently strong magnetic field normal to the initial polymer orientation, a transient periodic pattern develops. The transient nematic polymer orientation at the surface is found from the Euler-Lagrange equation for surface motion. The dynamics of the polymer at the surface is characterized by the ratio of the surface-polymer characteristic time to the bulk characteristic time, B. The actual response is limited by that of an orientational free surface (B = 0) and that of fixed polymer surface orientation (B double line arrow pointing right infinity). The magnitude of B has no effect on the field dependence of the observed wavelength. In the high-field regime, the dynamics of the velocity and bulk orientation and the final polymer orientation are independent of B. In the low-field regime, the dynamics of the velocity and bulk orientation, the strength of the flows, and the final polymer orientation are strongly dependent on B.