The formation, phase ordering, and evolution has been studied in lipid and liquid crystal (LC) colloidal aqueous mixtures as a function of LC concentration and thermal history. The lipid used was 2-oleoyl-1-palmitoyl-sn-glycero-3-phosphocholine (POPC) while the liquid crystal was pentylcyanobiphenyl (5CB). POPC is a naturally occurring lipid in eukaryotic cell membranes and mimics many of the properties of human cell walls. 5CB is a polar liquid crystal that exhibits a thermodynamically stable orientationally ordered (nematic) state at room temperature. Colloidal dispersions were made at various 5CB and POPC concentrations in water and studied via optical microscopy (phase contrast, confocal, florescence, and cross-polarizing) to probe phase order and evolution as well as by calorimetry to study phase transformations. Very large vesicles (larger than 100 micrometers) were observed to form that appear to use the phase separated 5CB droplets as scaffolds. Also, there appears a unique promotion of dye (used to image the lipid bilayers) crystallization within liquid crystal domains well above room temperature.

A number of compounds were synthesized with the ultimate goal being the synthesis of C₂ symmetric molecules which displayed thermotropic liquid crystalline behaviour. The compounds prepared were 4-alkoxy benzophenones, 3,4-bis-alkoxy benzophenones, 4- alkoxy dibenzylidene acetones, 3,4-bis-alkoxy dibenzylidene acetones and 4-alkoxy- 1, 9-diphenyl-nona-l,3,6,8-tetraen-5-ones. The length of the linear alkoxy side chain was varied from C₆H₁₃ to C₁₂H₂₅. All compounds were characterized by FTIR, ¹H, and ¹³C NMR spectroscopy. Mesophase behaviour of the synthesized compounds was investigated using differential scanning calorimetry and polarizing optical microscopy. It was determined that both the alkoxy side chain length, as well as the number of alkoxy side chains have an effect on the ability of this class of C₂ symmetric compounds to selfassemble into liquid crystalline phases. In addition, the overall core size and extent of conjugation also affected mesophase formation. The mono-alkoxy benzophenones and dibenzylidene acetones were non-mesogenic, while all four of the mono-alkoxy 1,9- diphenyl-nona-l,3,6,8-tetraen-5-ones (alkoxy side chain of lengths C₆H₁₃, C₈H₁₇, C₁₀H₂₁ and C₁₂H₂₅)self-assembled into nematic liquid crystalline phases. Increasing the number of alkoxy side chains from one to two per aromatic moiety helped induce liquid crystalline formation: the corresponding bis-C₆H₁₃ benzophenone and bis-C ₆H₁₃, bis C₈H₁₇, and bis-C₁₀H₂₁ dibenzylidene acetones were mesogenic, displaying smectic A (benzophenone) and nematic (dibenzylidene acetone) mesophases respectively.

For this thesis, the use of Liquid Crystal Polymer (LCP) as a system-level substrate and packaging material is investigated. Early in the research, recipes for fabricating on LCP were developed. With this knowledge, RF components were able to be fabricated. These devices include filters, antennas, phase shifters, and RF MEMS switches. To investigate the potential of using LCP as a system-level material, packaging properties and robustness were tested. This research demonstrated that LCP could be used to package something as small and delicate as an individual switch or as large as a 4-inch wafer. In addition, it was shown that MEMS switches could survive well over a hundred million cycles. This demonstrated that LCP could be used to create reliable, high performance systems. The culmination of this research was used to create two variations of a communication module. The first device was fabricated on one layer and a multi-layer approach was taken for the other device. These modules needed to be low-cost, low-loss, flexible, and capable of beam steering. This technology can be used for communication, sensing, detection, and surveillance for a broad scope of applications. To this date, they are by far the most sophisticated SOP on LCP ever achieved. This technology can be further developed to include more functionality, smaller size, and even better performance.

¡§Blue phase¡¨ LCD panels features the advantages of superior response times¡Bwide viewing angle and no requirement for alignment by rubbing greater than conventional LCD modes. Thus, recently several groups have been developed both scientific and technological interests in the blue phases. However, the blue phases only exist in the narrow temperature range, typically a few Kelvin below the phase transition temperature of materials, which has been a problem for practical applications such as fast light modulators or display. In this paper, we proposed polymer-stabilized liquid crystalline blue phase by photopolymerizing the monomers in the isotropic phase and discussed the theoretical model to describe the stability of the blue phases. The polymer networks play an important role in stabilizing a liquid crystal blue phase. The morphology of polymer network was determined by the process of polymerization condition, like exposure intensity and temperature. Moreover, scanning electron microscopy (SEM) images were used to understand directly the network structures and to find the regularity of temperature intervals. In the meantime, we successfully extended the temperature range of blue phase over 140oC under suitable conditions. Based on this research results, the different temperature interval properties of cholesteric blue phases will apply on various photoelectric elements in the future.

This study presents an optically switchable band gap of a 3D photonic crystal that is based on an azobenzene-doped liquid crystal blue phase. The trans-cis photoisomerization of azobenzene was induced by irradiation using 473nm light, and caused the deformation of the cubic unit cell of the blue phase and a shift in the photonic band gap. The fast back-isomerization of azobenzene was induced by irradiation with 532nm light. The crystalline structure was verified using a Kossel diffraction diagram. An optically addressable blue phase display, based on Bragg reflection from the photonic band gap, is also demonstrated. It can be written, erased, and rewritten repeatedly and exhibits a bright saturated color.

Nowadays, the common method to make an alignment layer of liquid crystal display is rubbing Polyimide (P.I.) thin film, Unfortunately, the rubbing method will reduce the yield of LCDs because of the particles, electrons, etc. created during rubbing on the surface of PI film. therefore many effort have been made to develop the non-contacting method such as photo alignment, plasma alignment, etc. This research focus on the non-contacting method, we hope it will reduce many pollution compared to rubbing alignment. Comparing with PI, polydimethylsiloxane (PDMS) possess higher transparency, batter stability in thermal and chemical, and lower surface free energy about 19 mJ/m^2. Due to the low surface free energy, PDMS can be used as a vertical alignment layer without any surface treatment. Methyl Red (MR) PDMS mixed with PDMS will be used as an alignment layer in this experiment. And the rod-like azo-dye will change its molecular to rotate because the absorption of linear polarized light. By changing the s MR to rotate, we can obtain a micro groove structure on PDMS surface and control the direction of liquid crystals further. Xenon lamp(100nm-1200nm) and the ultraviolet ray lamp (300-500nm) were used in this experiment for thin film. Samples were exposure with different incident angle and intensity of light, respectively, and discussed with different temperature as a factor. According to atomic force microscope ( AFM ) result, we can obtain a PDMS surface with micro groove structure by using Xe lamp and ultraviolet ray, and we can observe the changing tilt angle of liquid crystals by polarized optical microscope (POM).

This study investigates the optical properties of the twisted-nematic liquid-crystals at oblique directions and their applications. A large difference in the phase retardation and the twisted angle of the TN-LC from different viewing directions occurs at the low voltage regime. The proposed viewing angle switching (VAS) panel is developed using this large optically anisotropic behavior of the TN-LC. The proposed VAS panel is only perceived clearly at normal and downward directions in a narrow viewing angle mode to ensure high privacy protection, it highly promising for mobile device applications.

It is difficult to fabricate electrode, which have gradient electric field from edge to center by applying voltage. In this study, a gradient refractive index profile can be easily formed. We change the experimental parameter about exposure time of UV light, concentration of PVK film and the Cell gap to investigate the influence on focal length. As the exposure time increase, the differences in conductivity become large from edge to center, which create better index distribution. For high concentration of PVK films, UV light can not effectively improve the conductivity of transmittance zone, which case the worse index distribution. The increasing of cell gap resulting in poor distribution of the refractive index, which cause larger focal length.

Uniform lying helix(ULH) is a cholesteric LC structure with helical axix lying on the substrate. This structure has a periodic refractive index profile characteristics, so that it can be used as a phase grating. The ULH period can be tuned with different electric fields which provide with various applications. However, ULH is not a steady state in general, once the electric field shutdown, ULH texture will transform to planar texture. Generally, the ULH exist only under a few conditions: well homogeneous alignment and cell the ratio of gap to pitch smaller than 2 , in case the ratio more than 2, the ULH won¡¦t align well. We use two methods to make ULH align well at large cell gap pitch ratio; cooling down from isotropic temperature under electric field and putting mechanical stress on the sample, therefore we can get a well alignment and more stable ULH. We discuss the influence of different boundary conditions to the stability of ULH, and we discover that when d/p large than 10, the stability of ULH improved significantly. Then we study the influence in different alignment anchoring, we find stronger anchoring energy makes ULH transform to planar easily. So we use photo alignment to get weaker anchoring energy, and the ULH using photo alignment stable more than 24 hours. Finally we use a large d/p ULH as tunable phase grating, the pitch length can be tuned about 380nm with low power consumption, and it still have grating function when the field shutdown . Keyword: cholesteric liquid crystal¡Buniform lying helix¡Bgrating

Liquid crystal display is the most valuable and universal produce of the electric monitor presently. Due to the non-luminant display device, it must use the light source of the backlight module to reach display effect . In backlight module field , it is focus on the even distribution of the light source and the perfect appearance without any defect occurrence. Besides, the existence of film waving will cause the bad phenomenon .To improve and avoid the defect occurrence,through the workable analysis experiment can find the real element progressively . In the experiment , we will focus on the characteristic of the film material and each material¡¦s dimension which analyze by BM-7 and Nieo LCD analyzer,etc. According to angle orientation.From the result,we can realize that the stronger structure material and larger heat capacity of Diffusion Film, will decrease the expand and shrink for temperature , and film waving caused by temperature changing, which may resolve the film waving effectively.