Linear viscoelasticity and director dynamics of nematic liquid crystalline polymer melts

We describe the linear viscoelastic response of monodomains of unentangled nematic liquid crystalline polymers, using a generalized Rouse model. We calculate the dynamic relaxation functions analogous to the Leslie viscosities. As a consequence of the coupling of the macroscopic director orientation n to Rouse relaxation of the chain conformations, we predict: 1) a non-monotonic evolution of the director orientation after a step deformation and continuous tumbling in steady shear for extended chains (with no hairpins), and flow alignment of anisotropic Gaussian chains (with many hairpins), and 2) a phenomenon of "director recoil" in the response of n to a transient magnetic field.