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Title: Materials for chiral nematic liquid crystal applications
Author: May, Alison Linda
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2002
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Many chiral dopants occur naturally in one enantiomeric form and usually the other enantiomeric form is not readily available. In order to obtain the other enantiomer, it is often necessary to carry out chiral separations, which are both time consuming and expensive. There are, however, some examples of materials that are commercially available in both handedness and two such materials were identified, namely butane-2,3-diol and menthol. A range of diesters were synthesised from butane-2,3-diol and their virtual mesophase behaviour and physical characteristics were determined. These materials were not suitable chiral dopants due to a lack of mesomorphism and poor solubility. Esters of menthol were synthesised and these materials were much more suitable as chiral dopants because although they exhibited no mesomorphism, they had increased solubility and it was therefore possible to formulate selectively reflecting mixtures in the visible region of the electromagnetic spectrum. For SSCT applications, there is a need to synthesise chiral dopants, which have good solubility but also have wavelength insensitivity to temperature for the operating range of the device. A range of diesters based on isosorbide were synthesised, both symmetric and non-symmetric, and their virtual mesophase behaviour and physical characteristics were determined. A number of materials were identified as potential candidates for use in SSCT mixtures, showing good solubility and low wavelength sensitivity with temperature. A range of liquid crystal epoxides were synthesised, both nematic and chiral nematic compounds and their mesophase behaviour and physical characteristics were determined. Epoxides undergo cationic polymerisation, which leads to low shrinkage and good adhesion to a plastic substrate. Cationic polymerisation does not suffer from oxygen inhibition and it is therefore possible to form polymer networks in air. From the compounds that were synthesised it would be possible to prepare both nematic polymer films and coloured chiral polymer films.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Organic chemistry