Effect of the Network on the Director Fluctuations in a Nematic Side-Group Elastomer Analysed by Static and Dynamic Light Scattering

Abstract

Static and dynamic light scattering experiments were performed on monodomains of a crosslinked nematic side-group polysiloxane. The depolarized scattering caused by fluctuations of the nematic director was analysed. Due to a superposed strong static scattering produced by heterogeneities the fluctuating part of the scattering intensity was found to be rather small. In contrast 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 coupling to the network elasticity which dominate those originating from the Frank elasticity. Quantities describing the coupling as well as effective viscosities for the director reorientation were obtained.