Static and dynamic properties of liquid crystals
Static and dynamic properties of liquid crystals
This work is concerned primarily with the effects of molecular flexibility on liquid crystalline properties. In particular, the role of alkyl chains in determining static and dynamic properties of liquid crystals is investigated. Theories for the orientational ordering and thermodynamic properties of flexible liquid crystals are presented. Predictions of the theories are compared with experimental results for members of the bis- 4,4'-(cyanobiphenyloxy) alkane (BCBO-n) homologous series. Order parameters for different segments in the molecules are calculated and compared with experimental values obtained by deuterium N.M.R. spectroscopy. Theoretical and experimental values for the nematic-isotropic transition temperatures, entropies of transition and order parameters at the transition are compared. The properties of dimeric liquid crystals such as the BCBO-n compounds bear a strong resemblance to those of some liquid crystalline polymers. Similarities and differences between the dimeric and polymeric liquid crystals are interpreted in terms of their respective conformational distributions. A theory is developed to account for the effects of alkyl chains on the pretransitional behaviour of nematogens. The theory is used to predict the variation of the divergence temperature, T*, with chain length for homologous series of monomeric and dimeric liquid crystals. Finally, an investigation is made of the dynamic properties of nematic liquid crystals. A theory is developed to account for the site dependence of the spin-lattice relaxation times and spectral densities measured by N.M.R. spectroscopy. The theory, which explicitly allows for internal as well as external modes, is tested by comparison with experimental results obtained for members of the alkyl- and alkoxy- cyanobiphenyl series of compounds. (D73645/87)
University of Southampton
1986
Heaton, Nicholas James
(1986)
Static and dynamic properties of liquid crystals.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
This work is concerned primarily with the effects of molecular flexibility on liquid crystalline properties. In particular, the role of alkyl chains in determining static and dynamic properties of liquid crystals is investigated. Theories for the orientational ordering and thermodynamic properties of flexible liquid crystals are presented. Predictions of the theories are compared with experimental results for members of the bis- 4,4'-(cyanobiphenyloxy) alkane (BCBO-n) homologous series. Order parameters for different segments in the molecules are calculated and compared with experimental values obtained by deuterium N.M.R. spectroscopy. Theoretical and experimental values for the nematic-isotropic transition temperatures, entropies of transition and order parameters at the transition are compared. The properties of dimeric liquid crystals such as the BCBO-n compounds bear a strong resemblance to those of some liquid crystalline polymers. Similarities and differences between the dimeric and polymeric liquid crystals are interpreted in terms of their respective conformational distributions. A theory is developed to account for the effects of alkyl chains on the pretransitional behaviour of nematogens. The theory is used to predict the variation of the divergence temperature, T*, with chain length for homologous series of monomeric and dimeric liquid crystals. Finally, an investigation is made of the dynamic properties of nematic liquid crystals. A theory is developed to account for the site dependence of the spin-lattice relaxation times and spectral densities measured by N.M.R. spectroscopy. The theory, which explicitly allows for internal as well as external modes, is tested by comparison with experimental results obtained for members of the alkyl- and alkoxy- cyanobiphenyl series of compounds. (D73645/87)
This record has no associated files available for download.
More information
Published date: 1986
Identifiers
Local EPrints ID: 460833
URI: http://eprints.soton.ac.uk/id/eprint/460833
PURE UUID: 3c45b3b4-8c0f-4754-880b-f55e829a0555
Catalogue record
Date deposited: 04 Jul 2022 18:30
Last modified: 04 Jul 2022 18:30
Export record
Contributors
Author:
Nicholas James Heaton
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics