Hard-core liquid-crystal fibers

Self-organized liquid-crystal filamentary forms arise in many mixtures of the smectogen compounds at the transition from the isotropic melt. In some mixtures, a subsequent phase transition to the crystal or crystal smectic phase occurs at the core of the filaments. The resulting hard-core fibers act as anisotropic cylindrical lenses composed of the crystalline core surrounded by the nematic shell. In this work, the filaments, referred to as nematoids, have been obtained in several binary mixtures based on five mesogens: 4,4'-dipentylazoxybenzene, 4-dodecyloxy-4'pentylbiphenyl, 4-hexyl-4'nonyloxybiphenyl, 4-acetyl-4'-dodecylbiphenyt and 4"-pentylcyclohexyl 4-(4'-pentylcyclohexyl) benzoate within a silicone oil as an inert liquid. To characterize the molecular arrangements within the nematoids, we present the microinterferometric measurements of the refractive index distribution within the fibers and its changes at the phase transitions.