Motionally induced asymmetry parameter in NMR spectral patterns from a lyotropic lamellar phase

A large asymmetry parameter in the deuterium spectral pattern is idetified for the first time near the gel position of the of the potassium palmitate-water system. This asymmetry, measured at the deuterated terminal methyl position of the hydrocarbon chain, implies biaxial order suggesting cooperative tilt of the chains in the bilayer.     

Grating polarizers in waveguide miter bends

Rectangular grooved gratings have been fabricated on mirrors of waveguide miter bends. When the HE₁₁ mode was propagated in corrugated waveguide with diameter equal to approximately 12 wavelengths, these gratings performed in the same manner as predicted using plane wave theory. Two gratings with different groove depths in successive miter bends are sufficient to generate a rather wide range of polarizations. These gratings are particularly convenient in waveguide, which offers ease of alignment, compact transverse dimensions, and the possibility of vacuum operation.     

Mesomorphic Behavior of Some New Fluorene Compounds

Several new fluorene derivatives have been synthesized and their liquid crystalline polymorphic behavior examined. Specifically, 2-fluorenylmethylidene-4′-n-alkylanilines with different alkyl groups are compared with corresponding compounds wherein the alkyl groups have been replaced either by the alkoxy or other different groups. In addition, some of the 4-alkyl and alkoxybenzylidene-2-aminofluorenes have also been prepared for comparison. Many of these compounds show not only the nematic phase but also two smectic phases. The presence of a lateral substituent in analogous compounds decreases the nematic-isotropic transition by about 60[ddot]C.     

Electrooptic properties of polymer dispersed liquid crystals

An investigation of the electrooptic properties of polymer dispersed liquid crystals (PDLC) is presented. These materials are light modulating systems. They show a reversible optical response from an opaque state to a highly transmitting state under the action of an appropriate electric field which aligns the liquid crystal director. The switching voltage required to establish such an electric field has been monitored as a function of (i) the starting materials used for the preparation of the PDLCs, (ii) the ageing (curing time) of the PDLC cells. Other physical properties, such as the electrical resistivity and the dielectric constant of the materials, have been measured. The correlations between these properties have been studied. The PDLC switching voltage appears to be strongly correlated with the resistivity. Our data suggest that ionic impurities play a dominant role with respect to the electrooptic response of PDLC films.     

Liquid crystals and some of their applications

This paper is a brief review of some of the properties and applications of liquid crystals. By studying the references, a reader can gain a more extensive insight into the liquid crystalline state. Classifications of liquid crystalline materials and nomenclature characteristic of the field give the reader a working knowledge of the subject. Polymorphism is one of the common properties of liquid crystalline materials; the subject is covered in the text and summarized in tabular forms. The fundamental properties of liquid crystals are correlated with some of the behaviors and uses of liquid crystals. Optical properties, curvature elastic properties, surface effects, external field effects and hydrodynamics of the liquid crystalline state are discussed as necessary to describe recent practical applications; these include displays, storage of images and other electrooptic devices. Some of the results presented in this review were obtained under NSF Grant No. GH-34164X.