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The purpose of this thesis is to study the relation between surface optical anisotropy of polyimide thin film with different rubbing strength and liquid crystal alignment by means of reflection anisotropy spectroscopy (RAS). We discuss the surface properties of rubbed polyimide thin film by measuring the surface roughness, surface free energy and pretilt angle. RAS is a non-contact optical probe of surfaces. It measures the difference in reflectance of normal incidence linearly polarized light between two orthogonal directions in the surface plane, and we can obtain the surface character of sample by analyzing the signals. It is isotropic of polyimide thin film surface without rubbing, and reflection anisotropy (RA) signal is zero. The non-zero RA signal, i.e. anisotropic of surface, is revealed because of rubbed polyimide thin film surface. The RA signal is increasing with an increase in rubbing strength. In the results, we found that the pertilt angle is increasing with a decrease in surface free energy, and discovered the correlation between RA signal strength of characteristic wavelength and pretilt angle of liquid crystal at the rubbed polyimide thin film.

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Moisture induced damage of hot mix asphalt pavements has a significant economic impact in terms of excessive maintenance and rehabilitation costs. The moisture sensitivity of an asphalt mix depends on the combined effects of material properties, mixture design parameters, loading conditions and environmental factors. Traditional methods to assess moisture sensitivity of asphalt mixes rely on mechanical tests that evaluate the mix as a whole. These methods do not measure material properties and their role in moisture sensitivity of the mix independently. This information is very important to select materials resistant to moisture induced damage, or to modify locally available materials to improve their resistance to moisture damage for economic reasons. The objective of this research is to develop experimental and analytical tools to characterize important material properties that influence the moisture sensitivity of asphalt mixes. Quality of adhesion between the aggregate and bitumen binder in wet and dry conditions plays an important role on the moisture sensitivity of the asphalt mix. A part of this research work was to develop the Wilhelmy plate method and the Universal Sorption Device to measure the surface free energy components of the bitumen and aggregate with adequate precision and accuracy, respectively. Surface energy of these materials was used to identify parameters based on thermodynamics that can quantify their interfacial adhesion and propensity to debond in the presence of water. The thermodynamic parameters were shown to correlate well with the moisture sensitivity of asphalt mixes determined from laboratory tests. Specific surface areas of the aggregates were also used to account for the influence of mechanical interlocking at the micro scale. In some mixes, chemical bonding also contributes to the adhesion between bitumen and aggregate. The use of a micro calorimeter was introduced in this research as a versatile and fast tool to quantify the combined effects of physical and chemical adhesion between these materials.

Surface stabilized ferroelectric liquid crystal device (SSFLCD) has fast response time and exhibits excellent bistability. The SSFLCD has wide view angle because it operates in the in plane switching (IPS) mode. However, SSFLCD is a thin device, the uniform of its cell gap is difficult to control. When surface stabilized ferroelectric liquid crystal align, it is easy to bring in zigzag defect. In this study, the use of SU-8 photoresist to make photospacer by using photolithographic technique is studied. We control the thickness of photospacer at 1.08£gm. By using photospacer, we can get the cell with uniform cell gap. The influence of the property of the alignment layer and photospacer on surface stabilized ferroelectric liquid crystal alignment are discussed. We find that when the liquid crystal is injected anti-parallel to the rubbing direction, the alignment of Surface stabilized ferroelectric liquid crystal is easily influenced by photospacers. Wetting characteristics of the substrates is found to strongly affect the alignment of the ferroelectric liquid crystal.

In our study, we use mixed polyimide method and different rubbing conditions to modify surface characteristics for producing zigzag-free surface stablized ferroelectric liquid crystal(SSFLC) device. We utilize contact angle measuring system to obtain the surface free energy and also use rotating crystal method to measure the pretilt angle. Finally, we observe optical textures of SSFLC device with polarized optical microscope. In mixed polyimide experiment, we can approximately provide the pretilt angle between 0¢X and 90¢X, and we also demonstrate different pretilt angle is modified by the surface of different surface free energy. In the end of this experiment, we obtain the better optical texture of SSFLC device in 18.3¢X pretilt angle, but part regions of the texture still possess zigzag defects. In different rubbing conditions experiment, when the cumulative number of rub is 2 or 3 times in 0.3mm pile impression, we can produce zigzag-free SSFLC device in different horizontal polyimide alignment materials.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (p. 96-115).

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