摘要:

Using X-ray diffraction technique, we investigated the modulation of the bicontinuous cubic structure of monoacylglycerol (monoolein)-water systems by the presence of solutes. X-ray diffraction results demonstrated that chaotropic solutes (NaSCN, NaI, and urea) expand the lattice constants of fully hydrated monoolein in Pn3m cubic phase and on the other hand, that kosmotropic solutes (Na2SO4, NaCl, and sucrose) reduce the lattice constants. These results can be interpreted as suggesting that kosmotropes reduce the interfacial area and that chaotropes expand the interfacial area, by assuming independence of the molecular length of monoolein on the presence of solutes.

ISSN:1058-725X    

DOI:10.1080/10587250008024844

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The cubic D (CubD) and structured liquid (I1) phases of 4′-n-alkoxy-3′-nitrobiphenyl-4-carboxylic acids (ANBC-n, wherenis the number of carbons in the alkoxy group) have been investigated by X-ray diffraction techniques. The type of the CubD phase was identified asIa3dfor the homologues withn=15, 19, 20, 22, and 26, similarly to those ofn=16 and 18. On the basis of the model proposed by Luzzati and Spegt, the diameter (D/Å) and the length (L/Å) of the constituent rod are estimated and discussed. The structure of the I1phase and its dependence onnare also discussed. Forn=26, very surprisingly, another cubic phase withIm3msymmetry was observed at the lower temperature side of theIa3dcubic phase on heating.

ISSN:1058-725X    

DOI:10.1080/10587250008024845

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Heat capacities of optically isotropic mesogens, BABH(8), ANBC(16) and ANBC(18), have been measured by adiabatic calorimetry. The existence of solid-solid phase transitions with large entropy change seems to play a characteristic role for formation of the isotropic mesophase. Entropies of transition between the isotropic mesophases and the neighboring liquid crystalline phases are quite small. On the basis of the entropies of transition the possibility is suggested that the molecules might be aggregated in an identical manner in these two phases.

ISSN:1058-725X    

DOI:10.1080/10587250008024846

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Dielectric and13C-NMR measurements have been made to investigate the optically isotropic (IsoX) phase in dichiral compounds. The dielectric dispersions in the IsoX phase was found to be almost the same as that in the isotropic liquid (Iso) phase. The similar dynamic behavior in the Iso and IsoX phases is also observed in the13C-NMR measurement. These experimental facts suggest that the IsoX phase is not only optically isotropic but also has no cooperative motion, as in the Iso phase. An endothermic enthalpy change from the SmC* to IsoX phases associated with marked supercooling suggests that the formation and growth of the IsoX phase cannot be made in the Iso phase. Based on the phase diagrams of the binary mixtures of the stereoisomers, molecular chiral recognition was suggested to exist to form the IsoX phase.

ISSN:1058-725X    

DOI:10.1080/10587250008024847

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Liquid crystalline binary systems, consisting of poly(vinylalcohol) and an amphiphilic compound with hydrophobic nitroazobenzene and hydrophilic ethyleneimine units, were prepared, and their thermal and liquid crystalline properties were estimated. The amphiphilic compound exhibited a smectic A phase with a focal conic fan texture. The liquid crystalline binary systems showed a thermotropic smectic A mesophase. In the smectic A phase, a smectic layer structure with hydrophobic and hydrophilic sublayers was formed.

ISSN:1058-725X    

DOI:10.1080/10587250008024848

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This special volume of Molecular Crystals and Liquid Crystals contains the Proceedings of the first Anglo-Japanese Seminar on Liquid Crystals held in Nara, Japan, on 26th-28thMay 1999. The seminar was arranged to bring together members of the liquid crystal communities of Japan and the United Kingdom. The research undertaken by these two communities is at the forefront of international activities in many areas of this exciting subject. However, much of this research is of a complementary nature and so closer collaborations between the two communities would help to create a research base which would be considerably more competitive at the international level than simply the sum of the parts. The Seminar was envisaged as an invaluable forum in which to initiate co-operation between centres of liquid crystal research in our two countries as well as helping to enhance existing collaborations. It is to be expected that all such interactions would lead to the development of novel areas of liquid crystal science and technology.

ISSN:1058-725X    

DOI:10.1080/10587250008024823

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor