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Lyotropic Liquid Crystals (lyotropic + liquid_crystal)
Selected AbstractsFerromagnetic Mesostructured Alloys: Design of Ordered Mesostructured Alloys with Multicomponent Metals from Lyotropic Liquid Crystals,ANGEWANDTE CHEMIE, Issue 42 2009Yusuke Yamauchi Prof. Hoch geordnete, mesostrukturierte Mehrkomponentenlegierungen mit einstellbarer Zusammensetzung wurden synthetisiert (siehe TEM-Aufnahme mit Elektronenbeugungsmuster). Die Sättigungsmagnetisierung der Legierungen lässt sich über das Verhältnis der Metallkomponenten steuern. Durch das Legieren sind neuartige magnetische Funktionen zugänglich, über die Ein-Metall-Systeme nicht verfügen. [source] Crosslinked Bicontinuous Cubic Lyotropic Liquid-Crystal/Butyl-Rubber Composites: Highly Selective, Breathable Barrier Materials for Chemical Agent Protection,ADVANCED MATERIALS, Issue 24 2006X. Lu A breathable material that can act as a barrier to chemical agents is presented. The material is composed of butyl rubber and a crosslinkable lyotropic liquid crystal. Under the right synthesis conditions, a cubic phase with the desired selectivity properties results (see figure). The material is highly permeable to water vapor, but strongly impermeable to a mustard gas simulant. Application of the material for effective personal protection against such chemical agents is envisaged. [source] Synthesis of Nanohole-Structured Single-Crystalline Platinum Nanosheets Using Surfactant-Liquid-Crystals and their Electrochemical CharacterizationADVANCED FUNCTIONAL MATERIALS, Issue 4 2009Tsuyoshi Kijima Abstract Nanohole-structured single-crystalline Pt nanosheets have been synthesized by the borohydride reduction of Na2PtCl6 confined to the lyotropic liquid crystals (LLCs) of polyoxyethylene (20) sorbitan monooleate (Tween 80) with or without nonaethylene-glycol (C12EO9). The Pt nanosheets of around 4,10,nm in central thickness and up to 500,nm or above in diameter have a number of hexagonal-shaped nanoholes ,1.8,nm wide. High-resolution electron microscope images of the nanosheets showed atomic fringes with a spacing of 0.22,nm indicating that the nanosheets are crystallographically continuous through the nanoholed and non-holed areas. The inner-angle distributions for the hexagonal nanoholes indicate that the six sides of the nanoholes are walled with each two Pt (111), Pt (11) and Pt (010) planes. The formation mechanism of nanoholed Pt nanosheets is discussed on the basis of structural and compositional data for the resulting solids and their precursory LLCs, with the aid of similar nanohole growth observed for a Tween 80 free but oleic acid-incorporated system. It is also demonstrated that the nanoholed Pt nanostructures loaded on carbon exhibit fairly high electrocatalytic activity for oxygen reduction reaction and a high performance as a cathode material for polymer-electrolyte fuel cells, along with their extremely high thermostability revealed through the effect of electron-irradiation. [source] Formation of Lipid Emulsions and Clear Gels by Liquid Crystal EmulsificationINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2007T. Suzuki Recently developed emulsion technologies for the formation of fine emulsions, lipid emulsions and clear gels by liquid crystal emulsification were reviewed. As a basic information on liquid crystal emulsification, the structures and characteristic behaviours of lyotropic liquid crystals were summarized. Formation of a liquid crystalline phase was often seen in emulsions and biological systems. The significance of liquid crystal formation during emulsification was analysed by comparing the states and stabilities of emulsions prepared by different processes. Then uses of liquid crystals for formation of the characteristic emulsions and gels were also discussed. In liquid crystal emulsification, an oil phase is dispersed directly into the lamellar liquid-crystalline phase composed of surfactant, glycerol and water to prepare a gel-like oil-in-liquid crystal emulsion. This is followed by dilution with the remaining water to produce an emulsion. From the phase behaviour during emulsification and analysis of the local motion of the liquid crystal membrane by fluorometry, it was confirmed that the interaction between surfactant and a polyol molecule such as glycerol promotes hydrogen bonding and enhances the strength of the lamellar liquid crystal membranes, which results in the formation of oil-in-liquid crystal emulsions. The interaction between the liquid crystal and oil was analysed from the changes in molecular motion of the membrane at the oil-liquid crystal interface using the spin label technique of electron spin resonance (ESR). The fluidity of the liquid crystal membrane did not change when oil was added, and therefore oil-in-liquid crystal emulsions of various oils were prepared by the identical process. This lack of dependence of the liquid crystal membrane on oil results in the unique properties of liquid crystal emulsification, which can be used for oils of various polarity and different molecular constituents. When a self-organizing artificial stratum corneum lipid containing pseudo-ceramide was used as a principal component of the oil, a multilamellar emulsion of concentric lamellar structure was formed. The multilamellar emulsion supplements the physiological function of stratum corneum by the identical mechanism as natural intercellular lipids. High-pressure treatment of the lipid emulsion produced a gel-like emulsion crystal, in which the homogeneous nanoemulsion droplets were arranged in a hexagonal array. This review paper was presented at the Conference of the Asian Societies of Cosmetic Scientists 2005 in Bangkok. [source] Synthesis and Liquid Crystalline Properties of Mono-, Di- and Tri- O -alkyl Pentaerythritol Derivatives Bearing Tri-, Di- or Monogalactosyl Heads: The Effects of Curvature of Molecular Packing on Mesophase FormationCHEMISTRY - A EUROPEAN JOURNAL, Issue 19 2007Fabienne Dumoulin Dr. Abstract Self-organisation and self-assembly are critical to the stability of synthetic and biological membranes. Of particular importance is consideration of the packing arrangements of the various molecular species. Both phospho- and glycolipids can pack in ways in which curvature can be introduced into self-organised or self-assembled systems. For instance, it is known that the degree of curvature can affect the structures of any condensed phases that are formed. In this article we report on a systematic study in which we have varied the shapes of glycolipids and examined the condensed phases that they form. In doing so, we have also unified the shape dependency of lyotropic liquid crystals with those of thermotropic liquid crystals. In order to undertake this systematic study a range of different pentaerythritol derivatives was synthesized, which covers combinations of one to three alkyl chains of different lengths (6,7,9,10,11,12,14,16 carbon atoms) and three to one galactosyl heads. Mono- and di- O -galactosyl derivatives were prepared directly by glycosylation of the corresponding alcohols using 2,3,4,6-tetra- O -benzoyl or acetyl - ,- D - galactopyranosyl trichloroacetimidate or bromide as the donors; the tri- O -galactosyl derivatives were synthesized from O -alkyl- O -benzyl di- O -galactosyl pentaerythritol intermediates, followed by de- O -benzylation and glycosylation steps. All of the fully deprotected products were obtained by standard methods, and their self-organising and self-assembling properties examined. [source] | |||||||||||||