Transitions and instabilities in liquid crystal elastomers

Solid nematic liquids, formed by cross-linking polymer liquid crystals into elastomers, are shown to display novel and complex elasticity. The internal (nematic) direction suffers a barrier to its rotation and this couples to standard elasticity. By considering imposed strains we illuminate this elasticity and also demonstrate an entirely new nematic phase transition. At a critical strain there is a discontinuity of director rotation.