Light-scattering study of random disorder in liquid crystalline elastomers

We report on the structural study of a non-uniform (polydomain) director texture in nematic and smectic liquid crystalline elastomers. Polarised light scattering is used to probe the equilibrium director correlations in the region of transition under stress between the opaque polydomain material and the transparent, macroscopically monodomain elastomer. A characteristic four-peak scattering image is obtained in this transient region. The lobes of intensity are oriented along and perpendicular to the axes of crossed polarisers, with anisotropy along the direction of principal extension. We propose a theoretical model, based on the competition between the random disordering field due to the network crosslinks and the external aligning field (mechanical stress) to explain the observations.