Dynamics of soft and semisoft nematic elastomers

We analyze analytically and numerically the dynamics of how a nematic elastomer-an anisotropic rubber-responds elastically and orientationally to an imposed strain. Because positional and orientational degrees of freedom are coupled, the response is not the simple exponential one might expect for a viscous system. Indeed as a result of this nonlinear coupling, the different modes decay in two qualitatively different ways: with either two distinct or with the same exponential laws, depending, respectively, on whether there is or there is not complete reorientation of the molecular long axes. In addition, at the special values of the strain that form the boundaries between different equilibrium behaviors, relaxation is much slower, i.e., it follows a power law. [S1063-651X(99)05107-7].