Molecular structure and liquid crystallinity
Molecular structure and liquid crystallinity
The primary aim of this Thesis is to provide an insight into the synthesis and characterisation of novel thermotropic liquid crystals. Chapter 1 provides information with respect to some of the liquid crystal phases, the experimental techniques used to characterise them together with some structure-property relationships. In Chapter 2 the influence of sulphur on the phase and transitional properties of monomeric mesogens has been examined. The results indicate the major importance of geometry in determining the stability of the nematic mesophases formed by these mesogens. Chapter 3 describes the synthesis and transitional properties of cyanobiphenyl and cyanoterphenyl terminated liquid crystals containing a flexible 1,2 biphenyl dimethylene moiety as the central mesogenic core. A new class of sulphur-containing biphenyl trimers is presented in Chapter 4.
According to the results obtained, replacement of oxygen by sulphur results in a decrease in mesomorphic stability. In Chapter 5 we have compared the effect the inclusion of the ester group has upon the mesogenic properties of the ether linked, methylene linked, methylene-ether linked and carbonate linked cyanobiphenyl analogues. The ester linked dimers have increased mesomorphic stability over the ether, methylene and methylene-ether analogues while their clearing temperatures are almost identical to those of the carbonate analogues. The synthesis of laterally substituted low molar mass mesogens is described in Chapter 6. The results show that long chain lateral substituents do not prevent the occurrence of the mesomoprhic behaviour. In Chapter 7 we describe the results for the deuterium nuclear magnetic resonance experiments carried out for some of the mesogens from Chapter 6 with their lateral chains fully deuteriated.
University of Southampton
Santos, Flavio Bezerra dos
1997
Santos, Flavio Bezerra dos
Santos, Flavio Bezerra dos
(1997)
Molecular structure and liquid crystallinity.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The primary aim of this Thesis is to provide an insight into the synthesis and characterisation of novel thermotropic liquid crystals. Chapter 1 provides information with respect to some of the liquid crystal phases, the experimental techniques used to characterise them together with some structure-property relationships. In Chapter 2 the influence of sulphur on the phase and transitional properties of monomeric mesogens has been examined. The results indicate the major importance of geometry in determining the stability of the nematic mesophases formed by these mesogens. Chapter 3 describes the synthesis and transitional properties of cyanobiphenyl and cyanoterphenyl terminated liquid crystals containing a flexible 1,2 biphenyl dimethylene moiety as the central mesogenic core. A new class of sulphur-containing biphenyl trimers is presented in Chapter 4.
According to the results obtained, replacement of oxygen by sulphur results in a decrease in mesomorphic stability. In Chapter 5 we have compared the effect the inclusion of the ester group has upon the mesogenic properties of the ether linked, methylene linked, methylene-ether linked and carbonate linked cyanobiphenyl analogues. The ester linked dimers have increased mesomorphic stability over the ether, methylene and methylene-ether analogues while their clearing temperatures are almost identical to those of the carbonate analogues. The synthesis of laterally substituted low molar mass mesogens is described in Chapter 6. The results show that long chain lateral substituents do not prevent the occurrence of the mesomoprhic behaviour. In Chapter 7 we describe the results for the deuterium nuclear magnetic resonance experiments carried out for some of the mesogens from Chapter 6 with their lateral chains fully deuteriated.
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Published date: 1997
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Local EPrints ID: 463228
URI: http://eprints.soton.ac.uk/id/eprint/463228
PURE UUID: 312ef0f0-12c2-4fe3-96b5-c6d93ab58cec
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Date deposited: 04 Jul 2022 20:47
Last modified: 04 Jul 2022 20:47
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Author:
Flavio Bezerra dos Santos
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