Showing papers on "Lyotropic liquid crystal published in 1977"
TL;DR: The analysis of solubility and Chromatographic data shows that the overall salt effect can be described by the two antagonistic effects of salts on electrostatic and hydrophobic interactions.
850 citations
TL;DR: For a system having an axis of symmetry for the molecular motion which makes an angle ϑ with the external magnetic field, the secular part of the dipolar Hamiltonian is proportional to (1/2)(3 cos2ϑ−1).
Abstract: The shapes of NMR absorption lines, free induction decays, and Jeener echoes in systems such as lyotropic liquid crystals have been investigated theoretically and experimentally. For a system having an axis of symmetry for the molecular motion which makes an angle ϑ with the external magnetic field, the secular part of the dipolar Hamiltonian 〈Hd〉 (ϑ) is proportional to (1/2)(3 cos2ϑ−1). This leads to the characteristic logarithmic absorption line shape for nonoriented systems. The experimental consequences are illustrated with measurements on nonoriented samples of potassium palmitate–water in the lamellar liquid crystal phase.
77 citations
TL;DR: In this paper, methods for the production of high molecular compounds in the liquid crystalline (LC) state are discussed, including crystalline polymer melts, solutions of rigid chain polymers, block copolymer gels and polymers with side groups simulating the structure of liquid crystal molecules.
Abstract: Methods for production of high molecular compounds in the liquid crystalline (LC) state are discussed, including crystalline polymer melts, solutions of rigid chain polymers, block copolymer gels and polymers with side groups simulating the structure of liquid crystalline molecules. Examples of the realization of LC orientational order in melts and solutions of certain polymers are given, which clearly demonstrate the role of preliminary ordering of the macromolecules for the purpose of improving the physicomechanical properties of plastics. The results of work on preparation of polymers with mesogenic side groups are systematized and critically discussed. Methods are discussed for formation of thermotropic, LC polymers, which must be regarded as a special type of highly ordered, polymeric systems with spontaneously arising anisotropy of properties, occupying an intermediate position between amorphous and crystalline polymers.
53 citations
TL;DR: The degree of order forsolubilized specia is related to their chemical structure and the differences in solubilization capacity are shown to follow the disordering induced by the solubILizate.
Abstract: Compositions of water and amphiphilic substances may form liquid crystalline structures, which are characterized by a combination of long-range order and mobility at the molecular level. Different combinations of amphiphilic substances give a rich variety of different structures of the liquid crystals. The present treatment relates these liquid crystalline structures to the structure of the amphiphiles. The degree of order for solubilized specia is related to their chemical structure and the differences in solubilization capacity are shown to follow the disordering induced by the solubilizate. The role of liquid crystals in disperse systems is briefly treated and two examples are described of their importance in biological systems.
38 citations
TL;DR: The comparison between experimental condition in two experiments measuring MBBA bend flexo-coefficient and an analogy with lyotropic liquid crystals lead to the concept that the reason for the big....
Abstract: The comparison between experimental condition in two experiments measuring MBBA bend flexo-coefficient and an analogy with lyotropic liquid crystals lead to the concept that the reason for the big ...
32 citations
TL;DR: In this article, concentrated solutions of sodium salt of deoxyribonucleic acid have been observed under crossed polaroids and tested by means of the small-angle laser light scattering, the ultraviolet and infrared absorptions, the X-ray diffraction, the circular dichroism, and some other physical methods.
Abstract: The concentrated solutions of sodium salt of deoxyribonucleic acid have been observed under crossed polaroids and tested by means of the small-angle laser light scattering, the ultraviolet and infrared absorptions, the X-ray diffraction, the circular dichroism, and some other physical methods. The molecules of this poly-nucleotide aggregate to form rod-like assemblies (molecular clusters) at a certain polymer concentration and eventually form liquid crystalline structures. These liquid crystals are very similar to those found in the concentrated aqueous solutions of deoxygenated sickle-cell hemoglobin or of sodium salt of poly(glutamic acid).
26 citations
TL;DR: In this article, it was found that iodobenzene had the major influence on the alignments of the molecules and that fluorine tended to align the C 2 axis of the fluorobenene molecule at 90° to that preferred by iodobenenzene.
Abstract: Nematic lyotropic liquid crystals prepared from sodium decylsulphate and from decylammonium chloride have been used as solvents for benzene and its monohalogenated derivatives. The results of an N.M.R. investigation of these compounds indicate that vibrational corrections to the ortho dipolar couplings are about 1·5 per cent and that the structure of fluorobenzene in lyotropic solution is different from the microwave structure. It was found that iodine had the major influence on the alignments of the molecules. Fluorine tended to align the C 2 axis of the fluorobenzene molecule at 90° to that preferred by iodobenzene. This effect of substituent on the rotation by 90° decreased in the order I>Br>Cl>F. The preferential orientations were discussed in relation to the orientation of the superstructure of the nematic material. Only fluorobenzene orders, so that the carbon halogen bond is preferentially directed into the hydrocarbon water interface area and this significantly so only in the decylammonium phase.
20 citations
TL;DR: In this article, the formation of different phases of lyotropic liquid crystals is considered as a function of the relative importance of cohesive forces and affinity forces for water, and the conditions governing the state of these monolayers, and particularly of mixed monlayers, are analyzed.
Abstract: The formation of the different phases of lyotropic liquid crystals is considered as a function of the relative importance of cohesive forces and affinity forces for water. The elementary monolayer being the building stone of these phases, the conditions governing the state of these monolayers, and particularly of mixed monolayers, are analyzed. This shows how the composition of lipidic mixture determines its physical state in the presence of water: from the solid to the liquid crystalline state, and finally to complete solubilization in water. As biological applications, the case of he bile with formation of gallstones and that of the lipids in the arterial wall wit hformation of atheroma are given. Finally, the state of teh lipids in the model of the cell membrane is considered from a purely physical and cryatallographic point of view which fits with the biologica concepts.
14 citations
TL;DR: Proton-proton distance ratios and order parameters for partially oriented p-cresol in a lyotropic mesophase derived from potassium laurate were obtained in this article.
Abstract: Proton-proton distance ratios and order parameters for partially oriented p-cresol in a lyotropic mesophase derived from potassium laurate are obtained. The order parameters are the largest yet found for an ordered solute in a nematic-like lyotropic system. The dipolar couplings and structural data were independent of the rotational potential from 0–200 cal mol−1.
4 citations