Effect of the network on the director fluctuations in a nematic side-groupelastomer analysed by static and dynamic light scattering

Static and dynamic light scattering experiments were performed on monodomai ns of a crosslinked nematic side-group polysiloxane. The depolarized scatte ring caused by fluctuations of the nematic director was analysed. Due to a superposed strong static scattering produced by heterogeneities the fluctua ting part of the scattering intensity was found to be rather small. In cont rast to low molar mass nematics, the relaxation rates and strength did not show a significant dependence on the scattering vector. The results can be explained by restoring torques on the director originating from the couplin g to the network elasticity which dominate those originating from the Rank elasticity. Quantities describing the coupling as well as effective viscosi ties for the director reorientation were obtained.