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Liquid Crystal Mixture (liquid + crystal_mixture)
Selected AbstractsPhotoswitchable Gas Permeation Membranes Based on Liquid CrystalsADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Eric G, owacki Abstract We have fabricated switchable gas permeation membranes in which a photoswitchable low-molecular-weight liquid crystalline (LC) material acts as the active element. Liquid crystal mixtures are doped with mesogenic azo dyes and infused into commercially available track-etched membranes with regular cylindrical pores (0.40 to 10.0 ,m). Tunability of mass transfer can be achieved through a combination of (1) LC/mesogenic dye composition, (2) surface-induced alignment, and (3) reversible photoinduced LC-isotropic transitions. Photo-induced isothermal phase changes in the imbibed material afford large and fully reversible changes in the permeability of the membrane to nitrogen. Both the LC and photogenerated isotropic states demonstrate a linear permeability/pressure relationship, but they show significant differences in their permeability coefficients. Liquid crystal compositions can be chosen such that the LC phase is more permeable than the isotropic,or vice versa , and can be further tuned by surface alignment. Permeability switching response times are 5 s, with alternating UV and >420-nm radiation at an intensity of 2 mW/cm2 being sufficient for complete and reversible switching. Thermal and kinetic properties of the confined LC materials are evaluated and correlated with the observed permeation properties. We demonstrate for the first time reversible permeation control of a membrane with light irradiation. [source] Electrically Tuneable Liquid Crystal Photonic BandgapsADVANCED MATERIALS, Issue 38-39 2009Su Seok Choi Electrically controlled color tuning of the photonic bandgap and electrically induced multiple photonic bandgaps from a chiral nematic liquid crystal mixture doped with a ferroelectric liquid crystal. [source] Synthesis and functional properties of green fluorescent poly(methylmethacrylate) for use in liquid crystal systemsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 9 2003Ivo Grabchev Abstract The copolymerization of six 4-aminosubstituted-1,8-naphthalimide dyes comprising an allylic polymerizable group with methylmethacrylate has been investigated. The utility of the copolymers prepared as fluorescent component in polymer/liquid crystal systems has been examined. The photophysical and photochemical properties of the systems monomeric dye/liquid crystal and copolymer/liquid crystal have been also discussed. It has been shown that in a liquid crystal mixture 1,8-naphthalimide dyes and respective copolymer/liquid crystals have yellow,green fluorescent color with good photostability. Copyright © 2003 John Wiley & Sons, Ltd. [source] Photochromic composites based on porous stretched polyethylene filled by nematic liquid crystal mixturesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 2 2010Alexey Bobrovsky Abstract A number of the novel photochromic polyethylene (PE)-based liquid crystal composites were prepared and studied. The oriented stretched porous polyethylene films were used as the polymer matrices. Commercial liquid crystals doped with new photochromic compounds were introduced into PE films and photo-optical properties of the obtained composites were investigated. It was shown that a director of nematic liquid crystals is highly oriented along the stretching axis of PE films resulting in noticeable linear dichroism of the PE composite films. New approaches for reversible or irreversible image recording on PE LC composites by UV irradiation were demonstrated. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||