摘要:

A synthetic pathway is described for the preparation of the homologous series of (R)-(2-chloropropyl)-4-[4′-(n-alkoxy)benzoyloxy] benzoates with high optical purity. The liquid crystalline members of the series exhibit smectic A phase and can be used as chiral dopants in ferroelectric mixtures. The n=8 member was used in a mixture exhibiting monotropic and the n=9 member enantiotropic smectic C* phase around room temperature.

ISSN:1058-725X    

DOI:10.1080/10587259508041682

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Main chain polymers with a mesogen which contains the residue of muconic acid as the central unit were synthesized. Polymers with a T-like mesogen were obtained by thermal addition of N-substituted maleiaides. As a result of reaction with fumaroyl chloride and subsequent reaction with phenols or amines, polymers with X-like mesogen were obtained.

ISSN:1058-725X    

DOI:10.1080/10587259508041683

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Poly (1,6-heptadiyne) derivatives substituted with long side chains containing mesogen units such as poly(bis(4-methoxy-4′-hexyloxybiphenyl)- dipropargyl malonate) (PMHBDPM) exhibit unique characteristics typical to both liquid crystal and conducting polymer. PMHBDPM exhibits smectic A phase in consistent with temperature dependence of X-ray diffraction. Two stages of electrochemical doping corresponding to the charge transfers between dopants and polymer main chain and also between dopants and the core of the mesogen unit in the side chain are observed. Diffusion coefficient of dopants also exhibits drastic change at the phase transition between smectic A phase and isotropic phase. These characteristics have been discussed in terms of molecular orientations of both polymer main chains and substituted side chains. Unique dielectric properties and X-ray diffraction characteristics have been observed in a mixture of PMHBDPM with ferroelectric liquid crystal of low molecular weight.

ISSN:1058-725X    

DOI:10.1080/10587259508041684

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We present the results of the study of binary and multicomponent mixtures of cholesteryl enanthate with cholesteryl nonanoate and cholesteryl formiate. The aim of the study is the preparation of the system with phase transition temperature close to room temperature. Phase diagrams of binary mixtures are formed on the basis of data obtained by the optical microscopy and DS calorimetry and the shift of phase transition points of order 30–50° with respect to initial components was established. In the case of three- and four-component mixtures, we have identified the presence of enantiomorphic phase transitions of smectic and cholesteric type respectively. X-ray diffraction data have enabled the characterization of the structure of smectic or cholesteric mesophase and the calculation of molecular parameters: apparent length of the moleculesland the average intermolecular distance (D).

ISSN:1058-725X    

DOI:10.1080/10587259508041685

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The properties of H-bonded systems of alkyl- and alkoxybenzene acids have been studied both experimentally (by IR-spectroscopy methods) and theoretically near the solid crystal – liquid crystal phase transitions. Partial dissociation of the cyclic dimers accompanied by formation of open chain-like associates and monomers is found. Their amount depends on the temperature and phaee of the sample. The theoretical model of rearrangement of H-bonds is suggested. The rate constant of the cyclic dimer – open associate transition is estimated.

ISSN:1058-725X    

DOI:10.1080/10587259508041686

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Molecular organization of the different phases of a pyramidic liquid crystal film spread at the air-water interface has been investigated using Langmuir balance and current displacement techniques simultaneously. The mesogenic compound exhibits a main transition from an expanded phase to a metastable condensed phase. The results are in agreement with previous polarized and fluorescence light microscopy measurements and grazing incidence X-ray reflectometry. The study shows that the molecules are oriented edge-on in the condensed phase and side-on in the liquid expanded phase. The value of the dipole moment of the pyramidic molecules is given in the liquid expanded phase. Two kinds of displacement current curves were obtained depending on the kinetic of compression.

ISSN:1058-725X    

DOI:10.1080/10587259508041687

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Optical activity and light scattering measurements in the chiral-racemic system of 4-(2-methylbutyl) phenyl-4-hexyloxybenzoate (CE4) reveal a much larger decrease in the discontinuity at the third blue phase (BP III) to isotropic phase transition than reported previously using adiabatic scanning calorimetry on another compound. Whereas these new data show that the transition is still slightly discontinuous for the pure optical isomer of CE4, similar light scattering measurements on the pure optical isomer of 4″-(2- methylbutylphenyl)-4′-(2-methylbutyl)-4-biphenyl-carboxylate (CE2), which is more chiral than CE4, show no discontinuity at all.

ISSN:1058-725X    

DOI:10.1080/10587259508041688

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

DSC and DMA measurements were carried out on a collagen sample. Effect of humidity, Tensil modulus and Thermal denaturation between 30 °C and 130 °C were studied.

ISSN:1058-725X    

DOI:10.1080/10587259508041689

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The effect of addition of several nonnematic solute to nematic liquid crystal 5CB was studied. We found the increase of nematic-isotropic phase transition temperature in ANB/5CB mixture, contrary to the usually observed depression. The results were analyzed by a mean field treatment of mixture.

ISSN:1058-725X    

DOI:10.1080/10587259508041690

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The linear regression equation determining a dependence between crystal-nematic mesophase transition temperature, TN, and energy of the torsion deformation, ET, of the nematogene molecules has been obtained on the strength of calculations by the MM2 molecular mechanics method. It has been perfomed this transition occurs on reach such value TNwhich corresponds to the average quantity of the heat kinetic energy <EK> in respect to the two short molecule axes exceeding ET. The methods of consideration of the intermolecular association have been examined.

ISSN:1058-725X    

DOI:10.1080/10587259508041691

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor