Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 128-132). Also available in electronic version.

Thesis (Ph. D.)--Ohio State University, 2006. / Available online via OhioLINK's ETD Center; full text release delayed at author's request until 2009 Aug 16

Thesis (M.S.)--Oregon Graduate Center, 1977.

Deuterium (2H) and Nitrogen 14 (14N) NMR spectroscopy were used to investigate the molecular dynamics in one thermotropic and one lyotropic liquid crystal. Quantitative analyses of deuterium spectral densities of motion for three deuteron sites (ring and C-alpha) at two different Larmor frequencies (46 and 61.4MHz) are reported in the smectic A and C* phases of (S)-[4-(2-methylbutyl)phenyl]-4’-octylbiphenyl carboxylate (8BEF5-d15), a partially deuterated smectogen. 2H spectral densities for two deuteron sites on the chain (C1 and C2/C3) at Larmor frequency 61.4MHz and 14N spectral densities for the head group (NH4+) of the molecule decylammonium chloride (DACl) at 28.9MHz are reported in the lamellar phase of a partially deuterated sample, DACl-d11/H2O binary system. The motional model is the small step rotational diffusion for reorientations plus internal rotations in the strong collision limit. In the chiral C* phase of the first molecule, 8BEF5-d15, the helical axes are aligned along the external magnetic field and the deuteron spins appear to relax in a macroscopically uniaxial environment. After including the molecular tilt, the reorientation processes in the SmC* phase are found to have higher activation energies than those in the smectic A phase. Applying the same motional models to the lyotropic molecule DACl-d11, the tumbling motion of the long axis of the molecule in the aggregates is more rigorous in comparison to the molecular spinning motion. The similarity of deuterium spectral densities from the C1 and C2/C3 sites may indicate a relatively rigid unit of C1-C2-C3-C4 in the backbone. / February 2005

This dissertation reports a study of three kinds of liquid crystals using modern solid state NMR techniques: chiral rod-like liquid crystals, bent-core mesogens and disc-like liquid crystals. The properties and structures of liquid crystals are first introduced in Chapter 1. To understand the principles of different NMR phenomena, quantum mechanical theory is adopted to study different nuclear spin interactions and NMR techniques in Chapter 2. In the next part of this dissertation (Chapter 3-6), deuterium NMR methods are used to investigate the dynamics and structures of some liquid crystal phases. This is first done using the spin relaxation study. The parameters obtained from the model simulation can describe the molecular motion and internal dynamics in the fast motion region. Secondly, we investigate the dynamic process of discotic mesophases and unwound smectic C* phase using the line shape simulation study. 2D deuterium NMR exchange experiments are then performed to study the jump process in TGBA* phase and SmC* phase. The above investigation has demonstrated some powerful NMR methods for the dynamic study of liquid crystals. The third part of the dissertation (Chapter 7-9) is concerned with C-13 NMR techniques. After we introduce the quantum theory of different pulse sequences, theoretical models are presented to fit observations such as chemical shifts and dipolar splittings. Moreover high resolution liquid C-13 NMR experiments are introduced to study some bent-core molecules. They are useful to assist the carbon peak assignments of these molecules. The structure and ordering information of liquid crystals can be determined in their mesophases. Finally, a brief summary of the dissertation is given in the last chapter. / October 2007

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By using a special design of electrode pattern and the differential biased circuit, the gradient of the electric field distribution inside the liquid crystal sample cell can be achieved through the adjustment of driving voltage. The characteristics of positive or negative types of lens can be converted by changing the polarity of gradient within the sample cell which posses the homogeneous alignment. The liquid crystal lens with a variable focal length and the tunable types of focusing is demonstrated by utilizing the controllable distribution of electric field. This special design incorporating with the fabrication technology of TFT has a potential to develop a large scale of liquid crystal lens.

The liquid crystal display on the liquid crystal alignment is known to be influenced by the rubbing strength. In the thesis, in order to figure out the best condition for homeotropic alignment, we add the number of rubbing, which causes the increase of the rubbing strength. In the experiment, we discuss two parts. The first part discusses the relation between polarity and liquid crystal. The instrument used mainly is contact angle measurement system, which measures the contact angle between liquid and sample and calculates the polarity, the dispersion and the surface free energy. In the second part, we change the rubbing strength to analyze the influence of liquid crystal cell. Also, we use the electro-optical measurement to analyze the cell which is fabricated by different rubbing strength. It is at this part that we focus on analyzing the optical texture, transmittance, contract ratio, and sharpness. The sample¡¦s polarity rises as the rubbing strength increases. It is the influence of the liquid crystal pretitle angles that the polarity as well as the liquid crystal cell¡¦s optical property changes. Such changes could be seen in transmittance, contract ratio and sharpness

The Gas-to-liquids (GTL) processes produce a large fraction of by-products whose disposal or handling ordinarily becomes a cost rather than benefit. As an alternative strategy to market stranded gas reserves, GTL provides middle distillates to an unsaturated global market and offers opportunities to generate power for commercial purposes from waste by-product streams, which normally are associated with increased expenses incurred from additional handling cost. The key concept investigated in this work is the possibility of integrating the GTL process with power generation using conventional waste by-product steam streams. Simulation of the integrated process was conducted with the aim of identifying the critical operating conditions for successful integration of the GTL and power generation processes. About 500 MW of electric power can be generated from 70% of the exit steam streams, with around 20 to 25% steam plant thermal efficiency. A detailed economic analysis on the LNG, stand-alone GTL, and Integrated GTL Power-Generation plants indicates that the integrated system is more profitable than the other options considered. Justifying the technology and economics involved in the use of the by-product streams to generate power could increase the net revenue and overall profitability of GTL projects. This technology may be transferable to GTL projects in the world, wherever a market for generated power exists.