摘要:

The papers which follow were presented at the International Conference on Liquid Crystals held at Kent State University, August 16–20, 1965. There were 129 registrants in attendance. To the knowledge of the authors, this is the first truly international conference on the subject; there were conferences held in 1933 and 1958 under the auspices of the Faraday Society which had representatives from a number of European countries.

ISSN:0369-1152    

DOI:10.1080/15421406608083269

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Certain lipids form binary liquid crystalline (l.c.) phases with water. This is the only one case of a general high degree of interaction between the polar group of the lipid and water which is observed also as unduly large solubilities of water in lipids which are themselves insoluble in water. In the solid state, crystalline hydrates are formed in some cases. These systems are not only of great biological interest but the lipid-water interaction involves a little considered aspect of hydrogen bonding. The nature of these systems is being examined by the study not only of the lipids themselves but also their simple lower homologues.

ISSN:0369-1152    

DOI:10.1080/15421406608083270

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Two methods are described for the determination of the degree of orientation in thin films of nematic liquid crystals. Both methods are based on the measurement of infrared absorption intensities in the presence of a homogeneous d.c. electric field. In the first method the infrared dichroic ratio is determined by applying the electric field perpendicular to the direction of propagation of the polarized radiation. In the second method the electric field is applied parallel to the direction of propagation and does not require polarized radiation. An expression is derived for the dependence of the dichroic ratio on the magnitude of the applied field using a simple model of a domain acting as a rigid dipole.

ISSN:0369-1152    

DOI:10.1080/15421406608083271

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Nuclear magnetic resonance (n.m.r.) spectroscopy has been used to study smectic and waxy mesophases occurring in surfactant systems. The measurement of n.m.r. line widths as a function of temperature and surfactant concentration in a system containing crystalline, mesomorphic and isotropic phases produces information about the phase diagram of the system. The different kinds of phases are easily distinguished by their line widths but it is not always possible to distinguish different phases of a given type. Line widths of waxy type mesophases in saturated soaps have been found to be sufficiently characteristic of the phase to allow transition temperatures to be determined. Transition temperatures determined by n.m.r. agree well with those determined by other methods. Studies of the neat and middle phases in several systems indicate that the phase structures are probably identical for members of a homologous series of compounds. Neat phase lines are in general wider than middle phase lines and are more sensitive to changes in molecular structure. The length of the hydrocarbon portion of the surfactant molecule appears to be the primary factor determining the widths of the lines from middle phase. Mesophase line widths are found to be only slightly temperature and concentration dependent. N.m.r. lines from mesophases appear to have a characteristic shape. The shape can perhaps best be described as “super-Lorentzian”. The widths of n.m.r. lines from mesomorphic phases appear to be almost independent of the bulk viscosity of the systems.

ISSN:0369-1152    

DOI:10.1080/15421406608083272

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

This paper describes the structure of all the phases presented by rubidium soaps between 25° C and the melting temperature. Three types of structural elements have been identified:lamellae, discs and ribbons.

ISSN:0369-1152    

DOI:10.1080/15421406608083273

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

In 1889 Reinitzer,1working with cholesteryl benzoate, discovered a state of matter that was later ter med cholesteric liquid crystals. It is doubtful whether the discovery of liquied crystals would have been made at that time if the optical properties of the cholesteric phase were less pronounced. Like other liquid crystals, matericals in this state act as birefringent fluids. however, at that point the resemblance endns. The optical properties may be summarized as follows:2

ISSN:0369-1152    

DOI:10.1080/15421406608083274

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The cholesteric phase represents a unique situation in nature in that a highly colored material does not absorb incident radiation but transmits and scatters light selectively. The colors are not dependent upon specific electronic arrangements in the molecules as in the morke familiar dyes but, instead, are dependent on such factors as shape (steric factors) and dipole arragment. Thus, materials which exhibit cholesteric phases may be affected by a difference in carbon chain length or by the position occupied by a functional group.

ISSN:0369-1152    

DOI:10.1080/15421406608083275

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Liquid crystal mixtures were sandwiched between two transparent electrodes on glass and a direct or alternating potential was applied. The light scattering property of the liquid crystal changes upon application of voltage, the intensity varying from 1 to 10% of that scattered by a MgO diffuse surface. The maximum increase in intensity due to voltage was a factor of about six. The maximum wavelength shift was 40 nm to the blue by 80 V applied to a layer 10 μ thick. The response time varied from 0.03 to 0.5 sec.

ISSN:0369-1152    

DOI:10.1080/15421406608083276

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The influence of molecular structure upon liquid crystalline properties has received considerable attention, particularly with regard to the effects upon liquid crystalline transition temperatures of introducing lateral substituents into suitable aromatic molecules. The results from such investigations are reviewed. The effects of changing the terminal substituent in the molecule of a liquid crystalline compound are less clear, and results are presentned which show that the smectie and nematic properties are affected quite differently by the same substituents. The situation with regard to terminal substitents is discussed and illustrated by reference to homologous series of liquid crystalline compounds. It is concluded that no single order of terminal group efficiency can be expected to apply to all systems, as the nature of the molecule into which the terminal substituent is introduced plays an important part in determining the effect of the substituent on the liquid crystalline properties.

ISSN:0369-1152    

DOI:10.1080/15421406608083277

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor