Critical Stripe-Domain Instability of Nematic Elastomers

We present an experimental and theoretical investigation of the critical formation of stripe domains in monodomain nematic elastomers. Domains with alternating sense of director rotation are formed when the material is stretched perpendicular to the initial director alignment. A wide range of differing samples are shown to have a singular onset to director rotation at a threshold deformation and a second singular point at the end of the stripe domain region. All the data collapses onto a master plot revealing a universal behaviour. We analyse theoretically the threshold properties of the stripe phase. The analysis of free energy yields a first order transition into a fully-coarsened texture without any intermediate state of sinusoidal modulation