Liquid crystal solution

Two solutes were used to study diffusion in liquids, methylbenzene, which is a small molecule that can be approximated as a sphere, and a liquid crystal that is long and rodlike. The two solutes were found to move and rotate in all directions to the same extent in benzene. In a liquid crystal solvent the methylbenzene again moved and rotated to the same extent in all directions, but the liquid crystal solute moved much more rapidly along the long axis of the molecule than it... 

Azurmendi, H. F., Bush, C. A. Tracking alignment from the moment of inertia tensor (TRAMITE) of biomolecules in neutral dilute liquid crystal solutions. J. Am. Chem. Soc. 2002, 124, 2426-2427. 

Solvent viscosity vs, concentration plots for cellulose dissolved in TFA-CH2CI2 (70/30, v/v) do not exhibit a maximum (1I,S1) in contrast to the typicid behavior of polymer liquid crystal solutions. This same behavior is exhibited by other cellulose-solvent systems (52,fiQ). Conio et al. (59) si gest that due to the close proximity of the cholesteric mesophase to its solubility limit, it is only observed in a metastable condition. 

Determined from hexadeutero-l,4-dioxane from the nondeuterated derivative the single line remained sharp down to -150°C in liquid crystal solution H = 9.64 Real mol AS = 0.1 e.u. (83JMR354). 

Our understanding of lyotropic liquid crystals follows in a similar manner. The action of solvent on a crystalline substance disrupts the lattice structure and most compounds pass into solution. However, some compounds yield liquid crystal solutions that possess long-range ordering intermediate between solutions and crystal. The lyotropic liquid crystal can pass into the solution state by the addition of more solvent and/or heating to a higher temperature. Thermotropic and lyotropic liquid crystals, both turbid in appearance, become clear when they pass itno the liquid and solution states, respectively. 

Polymer liquid crystal solutions respond in an interesting way to a transient flow field. For example, a damped oscillatory response was observed upon a flow inception or flow reversal [150,156,157], and the strain was recovered to some extent after a creeping flow [158], These phenomena suggest that liquid crystal solutions have some textured structure, i.e., the spatial variation in the... 

In this article, we have surveyed typical properties of isotropic and liquid crystal solutions of liquid-crystalline stiff-chain polymers. It had already been shown that dilute solution properties of these polymers can be successfully described by the wormlike chain (or wormlike cylinder) model. We have here concerned ourselves with the properties of their concentrated solutions, with the main interest in the applicability of two molecular theories to them. They are the scaled particle theory for static properties and the fuzzy cylinder model theory for dynamical properties, both formulated on the wormlike cylinder model. In most cases, the calculated results were shown to describe representative experimental data successfully in terms of the parameters equal or close to those derived from dilute solution data. 

We have omitted discussing such interesting properties of liquid-crystal solutions as the Frank elastic constants, the Leslie viscosity coefficients, cholesteric pitch, textured structure (or defects), and rheo-optics. Some of them are reviewed in recent literature [8,167], but the level of their experimental and theoretical studies still remains largely qualitative. 

W. R. Burghardt and G. G. Fuller, Role of director tumbling in the rheology of polymer liquid crystal solutions, Macromolecules, 24, 2546 (1991). 

The liquid crystals were deposited in glass capillary columns up to 100 m long, 0 25 mm i.d The columns were whet using the dynamic method, by flowing 1 5 to 20% liquid crystal solutions in chloroform at a flow rate of 1 cm s through the column. The efficiency of the prepared columns was compared with that of common stationary phases (columns 100 m long and 0 25 mm i d exhibited an efficiency of up,to 350 000 theoretical plates for hydrocarbons with k 5) ... 

Several studies of both the H and, 3C-NMR spectra of isoxazoles have been reported. For isoxazole itself the parameters are recorded in Table Xj 278-283 anaiySjs Gf the H-NMR spectrum of isoxazole in a liquid crystal solution also gave the dipole-dipole coupling constants D35 = -64 + 2 Hz D45 = -300 2 Hz D34 = -487 2 Hz.281... 

Here we describe some recent work on liquid crystal solutions of cellulose and cellulose triacetate in TFA-CH2CI2 solvent mixtures. 

Sixou, P. Bosch, A.T. Lyotropic liquid crystal solutions of cellulose derivatives. In Cellulose Structure, Modification and Hydrolysis Young, R.A., Rowell, R.M., Eds. Wiley New York, 1986 205-219. 

This schema can be expanded in many ways. For example, other information about the sample can be added, such as whether the sample is a liquid, crystal, solution, etc. If necessary, a table might be used to store the sample ids of toxic or radioactive compounds, or of compounds monitored by some governmental regulatory agency. Rather than trying to foresee all possibilities and add columns to the sample table, it is much simpler and more robust to add new tables as new information becomes available or necessary. 

Smectic and nematic meso phases can be easily interconverted in the case of low-molar-mass compounds, and this gives melts of these compounds the characteristics of liquids. On the other hand, these melts are optically anisotropic because of their one-dimensional order, and so, have characteristic colors. Consequently, they are also known as liquid crystals. Solutions of rod-shaped macromolecules exhibit similar ordered behavior they are called tactoidal solutions. One-dimensional order can be induced in polymer melts by lowering the temperature below the melt or glass transition temperature, whereby the one-dimensional order is frozen in. The characteristic X-ray diagrams discussed above are then obtained. 

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