Sliding friction of nematic elastomers

We discuss steady-state mechanical dissipation at the interface between a nematically ordered elastomer and a substrate of hard asperities. A 'resin-like' approximation is invoked, according to which the nematic director is assumed to be rigidly coupled to the strain tensor in the elastomer. The resulting nematic correction to the friction coefficient scales with the degree of nematic order as Q². If the elastomer intercedes at a sheared substrate-fluid interface, there is an associated shortening of the effective hydrodynamic slip length seen by the fluid. This scenario is relevant to the biological functioning of slug pedal mucus.