The anchoring of Liquid Crystals (LCs) on surfaces patterned with functionalised Self Assembled Monolayers (SAMs) has been investigated. A range of pattern geometries and length scales have been used to explore the effects of surface patterning on the alignment of n-cyanobiphenyl (nCBs) LCs in their Smectic and Nematic phases and at the Nematic to Isotropic phase transition.

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.

Liquid crystalline thennosets (Lt.Ts) are a special class of materials which generated significant interest since they demonstrated the combination of the anisotropic physical properties of the mesophase and the specific properties of thennosets. Among them, the water barrier property of LeTs makes them very promismg materials for the potential applications in electronics and coatings. Liquid crystalline monomer, 4, 4'-diglycidyloxy-a-methylstilbene (DOMS), was synthesized and cured with different crosslinking agents, such as sulphanilamide, diaminodiphenylsulfone, diaminodiphenylmethane, and 2,4-Diaminotoluene. LeTs with different liquid crystalline structures were produced and their structural, dynamic mechanical and permeability properties are characterised. The conventional epoxy monomer, diglycidyl ether of bisphenol-A (BADGE) is also involved in our study and resins formed by BADGE and curing agents are used as comparisons to the DOMS LeT systems. Polarized optical microscopic tests were used to form time-temperature-transition (TTT) diagrams for different systems, which provide important information about the curing process of Lf.Ts. Relationships between curing conditions, structure and properties are created by TTT diagrams and microscopic observations. Differential scanning calorimetry and wide angle X-ray scattering tests demonstrated the typical smectic features of LeTs systems. In the dynamic vapour sorption tests, the extraordinary water barrier property of smectic LeT is revealed. The water permeability of LeT was reduced by 74.6% at 65 'C and by 63.7% at 85'C in comparison with the conventional thermoset. Smectic Le structure was proven useful in reducing the water permeation in epoxy thennosets. Dynamic mechanical analysis combined with computer modelling was employed to investigate the correlation between water permeation and inner structure of materials to clarify the mechanism of moisture diffusion and sorption in LCTs. The information and results obtained in this work would be of great importance for the potential industrial applications of LeTs. - i -

A detailed research of optical trapping of nematic and chiral nematic liquid crystalline droplets is presented, in which the central study is the droplet behaviour in the optical traps and relevant mechanisms. The study consists of two main works: a generalized investigation of the rotational dynamics of optically trapped droplets, and a novel rotational behaviour of specific chiral nematic droplets in linearly polarized laser traps. Studies Into the physical properties of nematic and chiral nematic liquid crystals, principles of optical tweezers, and the director configuration of liquid crystal droplets act as the important basis for the investigation into relevant mechanisms of the droplet behaviour in the optical traps.

Liquid crystalline phases are used in many everyday applications, such as display devices and household products, and their theoretical properties are of great interest. The virial series offers a sound theoretical approach for calculating the thermodynamic, structural and elastic properties of liquid and liquid crystalline phases. Many theories truncate the series at low order, but this can lead to inaccurate results and can miss the important phenomena. In this thesis, we use an eighth order virial expansion to calculate the equations of state of nematic liquid crystals, a~d the validity of the theory is determined by comparison to simulation results. We extend this theory to the novel cubatic liquid crystalline phase, a phase of matter for which little theoretical work exists. We use the extended theory to predict the stability of the phase, and again compare to simulation results to determine the validity of the theory. We also use the virial expansion to calculate structural properties of isotropic and nematic phases, including the direct correlation function and radial distribution function. We compare our theoretical results to those obtained from simulations, and test the accuracy of our theory against other theoretical predictions. These theories are then combined to calculate the elastic constants of nematic liquid crystals. The effects of confinement on liquid crystalline phases is explored using computer simulation. The phase behaviour and resultant frustration effects are reported. Bifurcation analysis is used to explore the effect of tethering polymer chains to nanorods. This approach.is then used to give a theoretical account as to why tethered particles should form liquid crystalline phases more readily than untethered particles. Molecular dynamics simulations are carried out on fused-sphere platelets, and the dynrurucal properties of the cubatic phase are explored using this system.

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