The effect of molecular structure on the mesogenic properties of liquid crystalline materials
The effect of molecular structure on the mesogenic properties of liquid crystalline materials
In this Thesis we present the results of investigations into the mesogenic properties of a number of different types of liquid crystalline materials. The first Chapter presents an introduction into the different mesophases formed by liquid and mesophase behaviour, together with various characterisation techniques. In Chapter Two we present the characterisation of an homologous series of the disc-like pentakis(phenylethynyl)phenyloxyalkanes (the so-called Superdiscs) and in particular their phase diagrams of mixtures with the inductor molecule 2,4,7-trinitrofluorenone (TNF). Following on from this, Chapter Three describes the results from deuterium NMR spectroscopy studies of one member of this series, the decyl homologue, and its equimolar mixture with TNF. In particular we concentrate on the nature of the monotropic Col1 phase and the unusual orientational ordering of the alkyl chain.
Chapter Four moves onto study the effect subtle changes in molecular structure has on the phases formed by calamitic liquid crystal dimers. We have prepared and characterised a number of non-symmetric dimers where the cyanophenyl group is linked to either a cyanobiphenyl or cyanoterphenyl moiety. The substitution of the cyano group in the cyanophenyl moiety is varied i.e. either ortho- or meta-substituted and phase behaviour and transitional properties are compared with the para-substituted materials.
In Chapter Five we develop a method of assessing the biaxiality of molecules based on the angle between two linked mesogenic units. The method is then tested against a number of bent and linear materials to assess the validity of the approach. Using this method we have prepared a number of V-shaped molecules based on the biphenyl moiety in an attempt to observe a thermotropic biaxial nematic phase.
University of Southampton
Perkins, Steven Patrick
c5ba9624-a561-46d2-ab02-cebd0f633054
1999
Perkins, Steven Patrick
c5ba9624-a561-46d2-ab02-cebd0f633054
Perkins, Steven Patrick
(1999)
The effect of molecular structure on the mesogenic properties of liquid crystalline materials.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
In this Thesis we present the results of investigations into the mesogenic properties of a number of different types of liquid crystalline materials. The first Chapter presents an introduction into the different mesophases formed by liquid and mesophase behaviour, together with various characterisation techniques. In Chapter Two we present the characterisation of an homologous series of the disc-like pentakis(phenylethynyl)phenyloxyalkanes (the so-called Superdiscs) and in particular their phase diagrams of mixtures with the inductor molecule 2,4,7-trinitrofluorenone (TNF). Following on from this, Chapter Three describes the results from deuterium NMR spectroscopy studies of one member of this series, the decyl homologue, and its equimolar mixture with TNF. In particular we concentrate on the nature of the monotropic Col1 phase and the unusual orientational ordering of the alkyl chain.
Chapter Four moves onto study the effect subtle changes in molecular structure has on the phases formed by calamitic liquid crystal dimers. We have prepared and characterised a number of non-symmetric dimers where the cyanophenyl group is linked to either a cyanobiphenyl or cyanoterphenyl moiety. The substitution of the cyano group in the cyanophenyl moiety is varied i.e. either ortho- or meta-substituted and phase behaviour and transitional properties are compared with the para-substituted materials.
In Chapter Five we develop a method of assessing the biaxiality of molecules based on the angle between two linked mesogenic units. The method is then tested against a number of bent and linear materials to assess the validity of the approach. Using this method we have prepared a number of V-shaped molecules based on the biphenyl moiety in an attempt to observe a thermotropic biaxial nematic phase.
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Published date: 1999
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Local EPrints ID: 464008
URI: http://eprints.soton.ac.uk/id/eprint/464008
PURE UUID: 291d1eb4-9256-4e3e-906b-484b00b146d0
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Date deposited: 04 Jul 2022 21:00
Last modified: 16 Mar 2024 19:06
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Author:
Steven Patrick Perkins
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