Light Scattering and Photon Correlation Spectroscopy of Filled and Confined Liquid Crystals

We present the results of photon correlation spectroscopy investigations of the influence of the confinement and interfaces on the behavior of nematic liquid crystals (NLC) filled with aerosil particles as well as dispersed in porous matrices of different pore geometry and size. The experiments show significant changes in physical properties of LC in such confinements and suggest that there is some evidence for glass-like dynamical behavior, although bulk LC do not have glassy properties. In NLC with nanoparticle network, at least two well identified decays were observed. We attribute the first decay to the director fluctuations of the bulk NLC. The second, glass-like decay, could be related to director dynamics in surface layers at aerosil - LC interface. The mode corresponding to motions of individual aerosil nanoparticles was not detected. This confirms that the aerosil particles form a network in the LC.