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Title: Surface controlled alignment of discotic liquid crystals on self assembled monolayers
Author: Al-Lawati, Zuhoor Hassan Habib
ISNI:       0000 0004 2747 9269
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2012
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The alignment of liquid crystal (LC) materials at surfaces is important for many applications such as those in the display industry and chemical and biological sensors. The alignment of thermotropic calamitic LC is an interesting field of research and has been studied well. However, little has been done in the area of discotic liquid crystals in general and in the field of the lyotropic discotic liquid crystal in particular. Discotic liquid crystals have gained interest recently due to their electrical conduction in one dimension, which makes them potentially useful for electronic devices such as transistors, light emitting diodes and solar cells. The alignment of discotic liquid crystals on self-assembled mono layers (SAMs) of alkanethiols has been the focus of this investigation. Both lyotropic (TP6E02M) and thermotropic (HA T11 and RJB66C) discotic liquid crystals were studied on various SAMs. Anchoring at the phase transitions was studied by tracking the shift in the Brewster angle as a function of temperature using Evanescent Wave Ellipsometry (EWE). Modelling to support the EWE experiments has been employed. For the nematic TP6E02M phase, EWE experimental results revealed random planar alignment on both CH3 and COOH functionalised alkanethiol SAMs. The shift in the Brewster angle was in good agreement with the modelling for a random planar alignment over a range of concentrations. In order to understand this behavior, EWE adsorption studies of dilute TP6E02M solutions on both high and low energy surfaces were also preformed. On each SAM a monolayer of the surfactant formed with the hydrophilic side chains of the TP6E02M molecules extending from the interface.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available