摘要:

A homologous series of cholesteryl n-alkyl carbonates has been prepared and their mesophases investigated. Different groups can be distinguished depending on the length of the alkyl chain. The first two members exhibit a monotropic high-temperature color band, the next two members an enantiotropic high-temperature color band, followed by a monotropic low-temperature color band without an interruption in the color sequence the following five members an enantiotropic high-temperature and a clearly separated low-temperature color band, and the last four members a monotropic high-temperature and a separated monotropic low-temperature color band. The mechanical sensitive enantiotropic high-temperature color band could only be observed in reflection under the microscope. The monotropic low-temperature color band, which is essentially induced by disturbance, was found in both reflection and transmission, with the colors of the same intensity.

ISSN:0369-1152    

DOI:10.1080/15421406608083055

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Starting from stigmasterol, phosgene and normal alcohols or alkandiols, two homologous series of stigmasteryl derivatives were synthesized, namely, the n-alkyl stigmasteryl carbonates and the α,λ-polymethylen bis(stigmastery1) carbonates. Some of the chloroformates required as intermediates were prepared and isolated.

ISSN:0369-1152    

DOI:10.1080/15421406608083056

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

A critical review of mesomorphic substances at room temperature is made.

ISSN:0369-1152    

DOI:10.1080/15421406608083057

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Leakage of Na+ across the surface of muscle cells has been observed to obey the Elovich equation, which previously was found to describe various electron transport processes at surfaces of inorganic semiconductors. Analogies between solid state electron transport and liquid or gel state ion transport permit the derivation of the Elovich equation for Na+ transport across the surface of the muscle cell, but only if it is assumed that muscle Na+ exists mostly in a complexed form. Direct experimental verification of this theoretical prediction was obtained by n.m.r. analysis of muscle Na+ The similarities between the behavior of ions in cells and electrons in semiconductors suggest the presence of some degree of order or crystallinity in cells, which suggests the applicability to biology of concepts derived from the study of liquid crystals.

ISSN:0369-1152    

DOI:10.1080/15421406608083058

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The lyotropic liquid crystals which are considered here are obtained with substances or mixtures of substances having amphiphilic molecules, the solvent being water. In order to understand the behaviour of these mixtures of amphiphilic substances it may be helpful to recall the behaviour of similar systems with only one amphiphilic substance, such as soaps or phospholipids. In fact lyotropic systems are also thermotropic and it is the cooperative action of the temperature and of the solvent which enables them to pass successively from the solid crystalline state to the liquid crystalline state and to the isotropic liquid or dissolved state.

ISSN:0369-1152    

DOI:10.1080/15421406608083059

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Adiabatic calorimetry was applied to some liquid crystalline substances. Especial reference is made for the first time to the transition between smectic modifications of different types. The enthalpy of transition, including pre-and post-transition effects, is 2100 joules/mole for the smectic B to smectic A transition of ethylp-(4-ethoxybenzylideneamino-)cinnamate, and only 100 joules/mole for the smectic C to smectic A transition of di-n-dodecyl 4,4′-azoxy-α-methylcinnamate.

ISSN:0369-1152    

DOI:10.1080/15421406608083060

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The problem of finding the equilibrium shape of a small particle by the Wulff construction is reviewed briefly, with emphasis on its applications to liquid crystals. The proof of Wulff's theorem is stated in a concise mathematical form. Some typical equilibrium shapes of liquid crystalline drops are described. When there is orientational order of the molecules in the liquid crystal but no translational order, the equilibrium shape may be an ellipsoid or a tactoid; when there is translational order as well, the shape may have plane faces, possibly with sharp edges and corners. The formation of the stepped drop, goutte à gradins, is interpreted as analogous to the stepwise roughening of a flat crystal surface whose orientation does not occur amongst the boundary surfaces of the Wulff shape.

ISSN:0369-1152    

DOI:10.1080/15421406608083061

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

120 substances with one or more liquid crystalline phases have been studied in 180 binary systems by the combined examination of the relations of miscibility and the observation of the textures by means of a micro heating stage. The examinations enable us to give two systems of liquid crystalline phases. The system based on the observation of the textures corresponds with the system based on the relations of miscibility. All liquid crystalline phases investigated can be divided into four groups, one nematic, and three smectic; the latter being called A, B and C. Some facts point to structural differences between the three smectic groups.

ISSN:0369-1152    

DOI:10.1080/15421406608083062

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Three homologous series of Schiff's base compounds have been prepared to investigate the relationship between chemical constitution and mesomorphism, by condensingp-n-alkoxybenzaldehydes withp-n-propoxy-,p-n-butoxy-andp-n-amyloxyanilines respectively and the various transition temperatures are recorded. These series exhibit the general mesomorphic properties as found in other analogous series. It is found that the lower homologues are either non-mesomorphic or nematic while middle members are smectic and nematic both and the higher homologues are purely smectic. In many homologues polymesomorphism in smectic phase is observed.

ISSN:0369-1152    

DOI:10.1080/15421406608083063

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Thirteenp-n-alkoxybenzylidene-p-aminobenzoic acids were prepared and their mesomorphic transition temperatures were determined. They exhibit mesophases of greater relative thermal stability than thep-n-alkoxybenzoic andp-n-alkoxycinnamic acids but 4′-n-alkoxydiphenyl-4-carboxylic acids exhibit greater thermal stability than the acids studied here thoughp-n-alkoxybenzylidene-p-aminobenzoic acids are longer by -CH+N- group in the monomer; this may be attributed to the stereochemistry of -CH+N- link causing the molecule to be broader than the 4′-n-alkoxydiphenyl-4-carboxylic acids. Comparatively higher thermal stability of mesophases of these acids is emphasized by the mesomorphic behaviour of methylp-n-alkoxybenzylidene-p-aminobenzoates which are purely smectic and the absence of anisotropic melt in the analogousp-n-alkoxybenzoates.

ISSN:0369-1152    

DOI:10.1080/15421406608083064

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor