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1

Molowa entropia orientacyjna i struktura cieczy zasocjowanych

Jadżyn J., Świergiel J.

Wiadomości Chemiczne

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2017

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[Z] 71, 7-8

517--532

EN

Research on the structural effects of intermolecular interactions not only brings us closer to a better understanding the macroscopic properties of liquids, but also allows one to modify these properties. Intermolecular dipolar couplings and hydrogen bonds are the most common interactions in liquids leading to formation of multimolecular entities with various structures. The natural rival of these interactions is the thermal agitation of molecules (kT), which aims to destroy the emerging structures. In this paper we present an experimental method to estimate the way of molecular self-assembly resulting from the simultaneous action of kT and intermolecular interactions. The method is based on the study of dipolar orientation effects induced by an applied electric field. As an experimental source of the information on these effects is temperature derivative of the static permittivity of tested liquid. That derivative is proportional to the liquid entropy change due to the ordering action of the electric field on the molecular dipoles. Here, we present the experimental results on temperature dependence of the static permittivity and increment of the orientation entropy of liquids where the self-association process realizes with two ways: dipolar couplings and hydrogen-bonds.

2

Dielectric and orientational properties of nematogenic 4-n-octyl(4'-cyanophenyl)benzoate

Bauman D., Jadżyn J., Wolarz E., Modlińska A., Dąbrowski R.

Opto-Electronics Review

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2010

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Vol. 18, No. 1

63-70

EN

Experimental studies of the dielectric properties in the nematic and isotropic phases of 4-cyanophenyl-4'-n-octylbenzoate (8CPB) have been performed in the frequency range from 50 kHz to 100 MHz. The relaxation process related to the rotation around the short molecular axis has been analysed. The results obtained have revealed that in the vicinity of the I-N phase transition, the molecular subdiffusional rotation process occurs. It is connected with the pretransitional effects which are observed both in the static and dynamic dielectric measurements. On the basis of the temperature dependence of the relaxation time in the nematic and isotropic phases, the orientational order parameter < P2 > has been determined. The values of < P2 > obtained in this way have been compared with those evaluated from the measurements of the polarized electronic absorption of the dichroic dye, dissolved as guest probe in the mesogenic host.

3

Static dielectric pretransitional effects in thermotropic liquid crystals

Jadżyn J., Czechowski G.

Opto-Electronics Review

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2008

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Vol. 16, No. 4

395-398

EN

The paper presents a review of recent results on static dielectric behaviour in vicinity of weakly first order transition from isotropic liquid to a liquid crystalline nematic phase of compounds used in opto-electronic devices. Temperature behaviour of static permittivity and its derivative are interpreted in terms of a basic thermodynamic quantities increment (internal energy, entropy and Helmholtz free energy) induced by a probing electric field.

4

4-n-Alkilobicyklo[2,2,2]octano-1-karboksylany 2-chloro-4-heptylofenylu : synteza i właściwości fizyczne nowych nematyków o ujemnej anizotropii dielektrycznej

Dąbrowski R., Dziaduszek J., Stolarz Z., Jadżyn J., Czechowski G., Kasprzyk M.

Biuletyn Wojskowej Akademii Technicznej

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2000

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Vol. 49, nr 8

43-61

PL

W pracy opisano syntezę 4-propylo-, 4-hektylobicyklo[2,2,2]oktano-1-karboksylanów 2-chloro-4-heptylofenylu. Zmierzono ich lepkość dynamiczną, gęstość, współczynniki załamania światła i przenikalność elektryczną w różnych temperaturach. Związki te są nematykami o ujemnej anizotropii dielektrycznej i niskiej temperaturze topnienia. Sugeruje się, że związki te mogą być stosowane jako modelowe w badaniach podstawowych dotyczących różnych właściwości związków ciekłokrystalicznych i efektów elektrooptycznych zamiast mniej trwałego MBBA, a także mogą być wykorzystywane jako anizotropowe rozpuszczalniki w badaniach spektroskopowych lub kinetycznych.

EN

2-chloro-4-heptylphenyl 4-alkylbicyclo[2,2,2]octane-1-carboxylates have been synthesized. They are low melting stable nematic compounds with a negative dielectric anisotropy. The temperature dependence of the bulk viscosity, density, optical indices, dielectric constants and elastic constants have been measured. It is suggested that these compounds may be used instead of MBBA for testing and demonstrating of different liquid crystalline properties and effects. They may be useful also as anisotropic solvents in spectroscopic studies.

5

A post Hartree-Fock Quantum-Chemical Study of the Dimerization of 2-Pyrrolidinone

Gorb L., Jadżyn J., Wojciechowski K.

Polish Journal of Chemistry

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1999

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Vol. 73, nr 9

1549-1554

EN

Results of an ab initio post Hartree-Fock study of the molecular structure, the relative stability, and the dipole moment of the hydrogen-bonded 2-pyrrolidinone dimers are reported.

6

Studies of trioctylmethylammonium chloride by dielectric spectroscopy

Elsebrock R., Stockhausen M., Czechowski G., Jadżyn J.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 11

2463-2470

EN

The dielectric relaxation studies of trioctylmethylammonium chloride (TOMAC) in pure state and in n-heptane, iso-octane and 1,4-dioxane solutions have been performed in the frequency range 100 kHz to 36 GHz at 20 degree C and 50 degree C. The dielectric spectra have been formally described as a sum of the conductivity and two relaxational contributions. The viscosity dependence of the relaxation time, corresponding to the contribution appearing in low frequency region, shows full analogy to the "limiting" behaviour of many electrolyte solutions.