Liquid crystal-crystal phase

Liquid Crystal Third Phase. In addition to micelles and microemulsion droplets, surfactants may form Hquid crystals. A Hquid crystal is a separate phase, which comes out of solution, not like the micelles or microemulsion droplets, which are microscopic entities within the solution. 

Separation of Stereoisomers Osing Liquid Crystal Stationary Phases... 

Thermotropic cholesterics were officially discovered2 in 1888 by the Austrian botanist Friederich Reinitzer, while studying the melting of cholesterol esters cholesteryl benzoate first melted to give a cloudy liquid that, at higher temperature, turned into an ordinary clear liquid. The cloudy liquid (the mesophase) was a thermotropic cholesteric liquid crystal. These phases... 

Under certain conditions, stiff rod-like helical polymers can spontaneously form lyotropic or thermotropic cholesteric liquid crystal (TChLC) phases. 

Metallotropic liquid crystals LC phases can also be based on low-melting inorganic phases such as ZnCl2 that have a structure formed of linked tetrahedra and... 

The systematic synthesis of non amphiphilic l.c.-side chain polymers and detailed physico-chemical investigations are discussed. The phase behavior and structure ofnematic, cholesteric and smectic polymers are described. Their optical properties and the state of order of cholesteric and nematic polymers are analysed in comparison to conventional low molar mass liquid crystals. The phase transition into the glassy state and optical characterization of the anisotropic glasses having liquid crystalline structures are examined. 

Figure 9. Expanded view of spectra to either side of the D-X interface in the decyldimethylphosphlne oxide/water system. The top spectrum is of the dry crystal (X), while the bottom spectrum is of the coexisting lamellar liquid crystal (D) phase.

Janini, G.M., Recent usage of liquid crystal stationary phases in gas chromatography, Adv. Chromatogr., 17, 231, 1979. 

Smith, T.R. and Wozny, M.E., Gas chromatographic separation of underivatized steroids using BPhBT liquid crystal stationary phase, J. High Resolut. Chromatogr. Chromatogr. Commun., 3, 333, 1980. 

A commercially available semetic phase composed of biphenylcarbox-ylate ester attached to the polysiloxane backbone of a fused silica column has been shown to be ideal for the separation of geometric isomers of polycyclic aromatics of various classes of compounds [14,15]. This column exhibits a wide semetic temperature range of 100-300°C and has been shown to be stable to at least 280°C. Liquid-crystal stationary phases have also been employed in SFC [16]. 

S. Rokushika, K. Naikwadi, et al., Liquid crystal stationary phases for gas chromatography and supercritical fluid chromatography, HRC CC J. High Res. Chromatogr. Chromatog. Commun., 5 480-484(1985). 

Betts, T.J., Charmaine, M.M. and Tassone, A.I. (1991) Use of a liquid crystal stationary phase at temperatures below its melting point for the gas chromatographic study of some volatile oil constituents, journal of Chromatography A 547, 335-344. 

Using 34, a Type I molecule, one can orient these molecules in liquid crystal (LC) phase such as a nematic ZLI-2452 (LC phase commercially available from Merck Co). Using polarized light, a different ratio D of the absorption E y and E is possible. The dichroic ratio... 

To improve the effectiveness of the chromatographic separation, a comparison study has been carried out on cyclodextrin and liquid crystal stationary phases Both materials function as "ordered" media with cyclodextrins the inclusion complex formation predominates, whereas the liquid crystals enable interaction of compounds with the ordered structure of the mesophase ... 

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