  Dense rubbery networks are highly entangled polymer systems, with significant
topological restrictions for the mobility of neighbouring chains and crosslinks
preventing the reptation constraint release. In a mean field approach,
entanglements are treated within the famous reptation approach, since they
effectively confine each individual chain in a tube-like geometry. We apply the
classical ideas of reptation dynamics to calculate the effective rubber-elastic
free energy of anisotropic networks, nematic liquid crystal elastomers, and
present the first theory of entanglements for such a material.
