title: Orientational order and finite strain in nematic elastomers.
abstract: Nematic elastomers exhibit large, spontaneous shape changes at the transition from the high-temperature isotropic phase to the low-temperature nematic phase. These finite deformations are studied here in the context of a nonlinear, properly invariant, variational theory that couples the orientational order and elastic deformation. The theory is based on the minimization of a free-energy functional that consists of two contributions: a nematic one due to the interaction of the mesogenic units and an elastic one arising from the stretching of the cross-linked polymer chains. Suitable choices for these two contributions allow for large, reversible, spontaneous shape changes in which the elastic deformation can affect the isotropic-nematic transition temperature. The change in transition temperature as well as the magnitude of the resulting spontaneous deformation is illustrated for various parameter values. The theory includes soft elasticity as a special case but is not restricted to it.
authors.affiliation: Department of Mechanical and Aerospace Engineering, Washington University in St. Louis, 1 Brookings Drive, Box 1185, St. Louis, Missouri 63130-4899, USA. efried@me.wustl.edu
authors.forename: Eliot
authors.initials: E
authors.lastname: Fried
authors.forename: Shaun
authors.initials: S
authors.lastname: Sellers