Liquid crystal/liquid-crystalline network composite systems: Structure formation and electro-optic properties

Abstract

The supermolecular structure and the electro-optic properties of a composite system consisting of a dense liquid-crystalline network and a low molar mass liquid crystal embedded in the network have been characterized. The composite systems were obtained by a photopolymerization of mixtures of a rigid mesogenic spacerless diacrylate and a low molar mass liquid crystal. They are characterized by a homogeneous distribution of the low molar mass liquid crystal in the network. The network has a cocontinuous periodic spinodal-type structure having a characteristic length scale of the order of 10 nm, if the low molar mass liquid crystal is removed or replaced by other solvents. The electro-optic switching properties are characterized by the fact that the active switching time and the width of the Frederiks transition are shifted to larger values as compared to those of the pure liquid-crystalline state. The decay times, on the other hand, are strongly reduced in the network. © 1992 Taylor and Francis Ltd.