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Induced smectic phases of 5CB-EBBA binary mixtures were investigated with respect to the structures, stabilities, and molecular motion. The highest stability of the ordered smectic phase was obtained when 5CB and EBBA were mixed at 1:2. At the same ratio, the transferred charges between 5CB and EBBA took the maximum, indicating the direct correlation of the induced phase to the charge-transfer interaction. Whereas, the molecular motion monotonically slowed down with increasing EBBA, which is ascribed to the decrease of the free volume. The stability and the slow molecular reorientation may be independently controlled in the induced smectics. [ABSTRACT FROM AUTHOR]

We developed photo-healable composite gels consisting of liquid crystal, microparticles, and gold nanorods. Upon irradiation with near-infrared light, the temperature of the composite gels rapidly increased above a gel-sol transition temperature by the photothermal effect of gold nanorods. Then, we successfully performed photoinduced gel-sol transition of composite gels based on the phase transition of liquid crystals induced by the photothermal effect. In addition, we achieved photo-healing of surface cracks made on the composite gels by means of the photothermal gel-sol transition. [ABSTRACT FROM AUTHOR]

Azobenzene liquid crystals, possessing two chiral moieties at both of the peripheral ends of the molecular structure, show characteristic chirality-originated liquid-crystalline and physical properties: emergence of stable smectic Q phases, a photoinduced phase transition between 3D liquid crystal phases, and induction of birefringence in the “liquid” phase. A dichiral compound, of which rigidity of the core is reduced by the introduction of ester groups, showed no smectic Q phases, but exhibited the antiferroelectric smectic C phase. The “liquid” phase of the less-rigid azo-compound was found to show electrically induced birefringence. [ABSTRACT FROM PUBLISHER]

Photonic control of defect structures and colloidal chains has been performed in azobenzene-containing liquid crystals dispersed with glycerol or water droplets. When we dispersed the colloidal droplets into the host liquid crystals, we could observe, at an initial state, Saturn ring and hedgehog around the glycerol and water droplets, respectively, indicating that normal alignment of liquid crystal molecules was induced on the droplets by the adsorption of the azobenzene molecules onto the droplets. In the case of the glycerol droplets, we achieved photochemical manipulation of the defect structures between Saturn ring and boojums on irradiation with ultra-violet and visible light. For the water droplets, an inter-droplet distance of the self-organized colloidal chain could be controlled by changes of the defect size on the photoirradiation. Photoinduced structural changes in the topological defects can be explained by the modulation of surface anchoring of the droplets by means of the cis-trans photoisomerization of the adsorbed azobenzene molecules. [ABSTRACT FROM AUTHOR]

We investigated photoresponsive behavior of azobenzene-containing liquid crystals dispersed with glycerol or water droplets. At an initial state, Saturn ring and hedgehog defects were formed around the glycerol and water droplets, respectively, indicating that homeotropic anchoring was induced by adsorption of the azobenzene molecules onto the droplets. For the glycerol droplets, we observed structural transformation between Saturn ring and boojums on irradiation with ultra-violet and visible light. For the water droplets, an inter-droplet distance varied by changes of the defect size on the irradiation. These phenomena would result from modulation of anchoring conditions by the photoisomerization of the adsorbed dyes. [ABSTRACT FROM AUTHOR]

Both peripheral ends of some straight-shaped mesogenic compounds, possessing a biphenyl or azobenzene as a central rigid core, have been systematically modified, and the effect on the liquid-crystalline properties investigated. A fluorinated moiety introduced into the peripheral alkyl chains stabilized the smectic phase, whereas that into the terminally positioned phenyl rings resulted in the appearance of the nematic phase. Introduction of phenyl rings into the middle of the flexible chains produced a well-defined smectic layered structure. Further introduction of another phenyl ring at each terminal end was found to show a significant effect on the determination of the clinicity. [ABSTRACT FROM AUTHOR]

We perform molecular dynamics simulations using a simple model system of liquid crystal substance on air-water interface. A system of soft spherocylinders, which do not show smectic C phase in bulk, exhibits a tilted smectic phase when interacting with a model water plane. We observe not only macroscopic properties such as the pressure-surface area curve, but also correlation functions and diffusions as well. [ABSTRACT FROM AUTHOR]

Unique characteristics were observed in phase-type gratings which were formed in polymer liquid crystal (PLC) films. We have investigated the formation and the properties of the holographic gratings recorded in PLCs with azobenzene moieties (photoresponsive unit). Two types of PLCs were examined: homopolymers of azobenzene monomers (PALC) and copolymers with a tolane moiety (mesogenic unit with a high birefringence) in the side chain. The diffraction efficiency (η) was enhanced in the LC phase. We obtained the value of η of 31% while it was less than 1% in a glassy state in the Raman-Nath regime. This difference may be due to the modulation of refractive index (Δn) based on alignment change of mesogens in the PLC film. In addition, we attempted the holographic image storage of three-dimensional (3-D) objects in the PLC film. The 3-D object was reconstructed with high resolution (>5,000 lines/mm). [ABSTRACT FROM AUTHOR]