The influence of the linking group on the liquid crystallinity of dimeric molecules
The influence of the linking group on the liquid crystallinity of dimeric molecules
There is much interest in liquid crystal dimers because of their unusual transitional behaviour, which exhibits a pronounced odd-even effect. The properties of such dimers have been found to depend on the length and parity of the flexible spacer as well as the geometry of the linking group. Chapter One provides an insight into the background of liquid crystals, introducing the different liquid crystalline phases as well as the techniques used to characterise them. The nature of structure-property relations with regard to liquid crystal dimers is also explained. The influence of the spacer length and parity on liquid crystalline behaviour is discussed on Chapter Two, showing the effect of increasing the chain length of the α, ω-bis(4-cyanobiphenyl-4'-yloxy)alkanes from two up to twenty-two methylene groups. Chapter Three describes the effect of replacing an ether link between the spacer and the mesogenic groups with sulphur. According to our results substituting an oxygen atom for a sulphur atom decreases the mesogenic range. The effect of decreasing the bond angle is discussed and compared with theoretical predictions. In Chapter Four, a series of non-symmetric cyanobiphenyl dimers is presented, with an ether link at one end of the flexible spacer and a thio link at the other. The transitional behaviour is compared with that of the symmetric parent dimers so as to be able to understand fully the effect of the linking group on the mesomorphic ability of liquid crystal dimers. The synthetic procedures used to synthesise all of the compounds studied in this Thesis, together with the spectroscopic data necessary for their characterisation are shown in Chapter Five.
University of Southampton
1999
Farrand, Fiona Jane
(1999)
The influence of the linking group on the liquid crystallinity of dimeric molecules.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
There is much interest in liquid crystal dimers because of their unusual transitional behaviour, which exhibits a pronounced odd-even effect. The properties of such dimers have been found to depend on the length and parity of the flexible spacer as well as the geometry of the linking group. Chapter One provides an insight into the background of liquid crystals, introducing the different liquid crystalline phases as well as the techniques used to characterise them. The nature of structure-property relations with regard to liquid crystal dimers is also explained. The influence of the spacer length and parity on liquid crystalline behaviour is discussed on Chapter Two, showing the effect of increasing the chain length of the α, ω-bis(4-cyanobiphenyl-4'-yloxy)alkanes from two up to twenty-two methylene groups. Chapter Three describes the effect of replacing an ether link between the spacer and the mesogenic groups with sulphur. According to our results substituting an oxygen atom for a sulphur atom decreases the mesogenic range. The effect of decreasing the bond angle is discussed and compared with theoretical predictions. In Chapter Four, a series of non-symmetric cyanobiphenyl dimers is presented, with an ether link at one end of the flexible spacer and a thio link at the other. The transitional behaviour is compared with that of the symmetric parent dimers so as to be able to understand fully the effect of the linking group on the mesomorphic ability of liquid crystal dimers. The synthetic procedures used to synthesise all of the compounds studied in this Thesis, together with the spectroscopic data necessary for their characterisation are shown in Chapter Five.
This record has no associated files available for download.
More information
Published date: 1999
Identifiers
Local EPrints ID: 463607
URI: http://eprints.soton.ac.uk/id/eprint/463607
PURE UUID: 1dc4baa3-5158-4588-be57-4e70f176922b
Catalogue record
Date deposited: 04 Jul 2022 20:54
Last modified: 04 Jul 2022 20:54
Export record
Contributors
Author:
Fiona Jane Farrand
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