| Abstract: | In liquid-crystal elastomers, the simultaneous presence of rubber elasticity due to the crosslinked backbone chains and of optical birefringence due to the mesogens in the side chains lead to exceptional physical properties. An elastic deformation of the network influences the order of the mesogens and, therefore, the optical properties. A theory based on a Landau-de Gennes expansion of the free energy is proposed. In the opaque polydomain phase, the local orientation is given by a compromise between the external mechanical field and a local anchoring interaction. As the field is increased, it becomes energetically favorable for the mesogens to align parallel to the mechanical field, and a transition to a transparent monodomain structure occurs. Results for the average orientation, the stress and the chain conformation are given. |
