Lyotropic liquid crystalline phases

Like other surfactants, alkanesulfonates generate lyotropic liquid-crystalline phases. But the phase equilibria can only be inadequately described because of the enormous experimental difficulties in, for instance, establishing an appropriate equilibrium. Nevertheless, for simple ternary systems the modeling of surfactant-containing liquid-liquid equilibria has been successfully demonstrated [60],... 

A. Pampel, E. Strandberg, G. Lindblom, F. Volke 1998, (High-resolution NMR on cubic lyotropic liquid crystalline phases), Chem. Phys. Lett. 287, 468-474. 

Nano-electrode arrays can be formed through nano-structuring of the electrocatalyst on an inert electrode support. Indeed, if the current of the analyte reduction (oxidation) on a blank electrode is negligible compared to the activity of the electrocatalyst, the former can be considered as an insulator surface. Hence, for the synthesis of nanoelectrode arrays one has to carry out material nano-structuring. Recently, an elegant approach [140] for the electrosynthesis of mesoporous nano-structured surfaces by depositioning different metals (Pt, Pd, Co, Sn) through lyotropic liquid crystalline phases has been proposed [141-143],... 

G.S. Attard, P.N. Bartlett, N.R.B. Coleman, J.M. Elliott, J.R. Owen, and J.H. Wang, Mesoporous platinum films from lyotropic liquid crystalline phases. Science 278, 838-840 (1997). 

Another feature of surfactant-water systems is that they can also aggregate into lyotropic liquid crystalline phases when Intermicellar interactions are significant. Typically, non-Newtonian behavior is usually found for these liquid crystalline phases. For the 3LDA0/ISDS mixed system, all evidence suggests that they do form liquid crystalline phase. 

A compound that has two immiscible hydrophilic and hydrophobic parts within the same molecule is called an amphiphilic molecule (as mentioned earlier). Many amphiphilic molecules show lyotropic liquid-crystalline phase sequences, depending on the volume balances between the hydrophilic part and the hydrophobic part. These structures are formed through the microphase segregation of two incompatible components on a nanometer scale. Hand soap is an everyday example of a lyotropic liquid crystal (80% soap + 20% water). 

The structure and function of cell membranes have long been associated with lyotropic liquid crystalline phases. Since most of the glycolipids are amphitropic (both thermotropic and lyotropic) their was an increase of interest in the comparison of the structures of both types of mesophases formed by the same compound. 

Interestingly, tobacco mosaic virus, discussed in Section 5.2.1, owing to its rodlike shape forms lyotropic liquid crystalline phases which can be analysed theoretically [66]. 

The appearance of tubular myelin-like structures in swollen lecithin was observed by light microscopy well before the systematic investigation of liposomes [351-352]. Similarly, it was also demonstrated some time ago that the addition of calcium ions converted phospholipid liposomes to cochleate cylinders [353]. Subsequent studies have, however, revealed that the system is extremely complex. For example, examination of the phase-transition behavior of synthetic sodium di-n-dodecyl phosphate [(C12H2sO)2PO2Na+ or NaDDP] and calcium di-n-dodecyl phosphate [Ca(DDP)2] showed the presence of many diverse structures [354]. In particular, hydrated NaDDP crystals were shown to form lyotropic liquid-crystalline phases which transformed, upon heating to 50 °C, to myelin-like tubes. Structures of the tubes formed were found... 

For this water concentration, the micellar region for the bile salt mixture is large for all oleyl compounds except oleic acid. Oleic acid is distinguished from the other compounds in that it does not form a lyotropic liquid crystalline phase spontaneously in water and, similarly, is present as oil droplets in bile salt solution when its micellar solubility is exceeded. Figure 1 shows also that the micellar area of an equimolar mixture of monoolein and sodium oleate is considerably greater than that of an equimolar mixture of monoolein and oleic acid, indicating that fatty acid ionization also enhances micellar solubility when monoolein is present. The equimolar mixture of sodium oleate and oleic acid has a micellar area similar in size to that of monoolein, as does the equimolar combination of all three compounds. 

Micellar and Lyotropic Liquid Crystalline Phases Containing Nonionic Active Substances... 

The present knowledge about molecular organization in lyotropic liquid crystalline phases is summarized. Particular attention is given to biologicaly relevant structures in lipid-water systems and to lipid-protein interactions. "New findings are presented on stable phases (gel type) that have ordered lipid layers and high water content. Furthermore, electrical properties of various lipid structures are discussed. A simple model of l/l noise in nerve membranes is presented as an example of interaction between structural and electrical properties of lipids and lipidr-protein complexes. 

Lyotropic liquid crystalline phases had been utilized technically for a long time before their structures were known. A milestone in the elucidation of their structure was the introduction of the liquid chain concept. In 1958, on the basis of evidence from IR spectroscopy, Chapman pro-... 

The lyotropic liquid crystalline phases relevant to biological systems consist of water and lipids and usually proteins also. The lipids listed in Table I occur in cell membranes all form liquid crystalline phases with water. 

Kinetic studies have been important in many areas of chemistry, but, to date, classic kinetic approaches have not played a major role in the area of colloidal science related to self-organisation of surfactants. Although micellar kinetics were investigated in some detail in the 1970s, related work involving other self-assembly systems, e.g., vesicles, lyotropic liquid-crystalline phases, have been limited. 

Table 1. Examples of stiff-chain polymers able to form a lyotropic liquid-crystalline phase when dissolved in the solvent listed in third column... 

The unusual optical properties of liquid crystals had been remarked upon and described for several centuries before their uniqueness as a state of matter was recognised. Their early reports described the strange melting behaviour and appearance of some naturally occurring materials, either as pure compounds or as gels in water, which have now been shown to be thermotropic or lyotropic liquid crystals. Thermotropic liquid crystalline phases are formed under the action of heat, see Figures 2.1 and 2.2, and the lyotropic liquid crystalline phases are formed by the action of a solvent, such as water, usually with an amphiphilic compound. However, the nature of these materials, or indeed their exact... 

The results showing augmentation of the surfactant alcohol ratio for maximum aqueous solubility with added electrolytes are not amenable to a similarly simple explanation, and the influence of the presence of electrolytes must be discussed against the relative stability of the inverse micelles and of the lyotropic liquid crystalline phase with which the inverse micellar solution is in equilibrium (7). 

Similar to germanium sulfides or selenides, [SiqSeio] adamantine clusters also exist and have been found to form mesostractured semiconductors with Pt + when templated by the lyotropic liquid-crystalline phase of alkylpyridiniinn surfactant [Ci6H33NC5H5]Br. This mesophase designated as CiePyPtSnSe has a band gap of 1.5 eV. 

This chapter focuses on the fixation of lyotropic liquid crystalline phases by the polymerization of one (or more) component(s) following equilibration of the phase. The primary emphasis will be on the polymerization of bicontinuous cubic phases, a particular class of liquid crystals which exhibit simultaneous continuity of hydrophilic — usually aqueous — and hydrophobic — typically hydrocarbon — components, a property known as bicontinuity (1), together with cubic crystallographic symmetry (2). The potential technological impact of such a process lies in the fact that after polymerization of one component to form a continuous polymeric matrix, removal of the other component creates a microporous material with a highly-branched, monodisperse, triply-periodic porespace (3). 

Friberg SE, Wohn CS, Lockwood FE. The influence of solvent on nonaqueous lyotropic liquid crystalline phase formed by triethanolamine oleate. / Pharm Sci 1985 74(7) 771-773. 

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