Foram estudadas fases micelares do sistema lauril (dodecil) sulfato de sodio (sls)/agua/decanol nos estados isotropico i e liquido-cristalino por espalhamento de raios-x com enfase nas transicoes de fase iSETAhexagonal hALFA e iSETAnematica nc. O estudo das posicoes do pico intermicelar no sistema binario sls/agua, indica que as micelas sao estaveis e levemente anisometricas nas fases i concentradas com empacotamento local de micelas esferoidais. Ocorre crescimento micelar na vizinhanca da transicao iSETAhALFA. A analise da curva de espalhamento i (q) em concentracoes menores (ate 9% em peso de sls) mostra ser possivel a determinacao da funcao distribuicao de distancias p (r), em casos especificos onde i (q) e dominada por um pico predominantemente relacionado a estrutura interna micelar. As anisometrias micelares NI sao deduzidas dos valores de dmax sendo p (r)=0 para r> OU =dmax obtemos NIAPROXIMADAMENTE IGUAL1.5. A analise das curvas de espalhamento de solucoes mais concentradas evidenciam que as micelas crescem mais por adicao de decanol ao longo da transicao de fase iSETAnc (NIAPROXIMADA MENTE IGUAL3) do que por aumento de concentracao de anfifilico no sistema binario ao longo de iSETAhALFA (NIAPROXIMADAMENTE IGUAL2,4). Estes resultados sao discutidos no ambito de previsoes teoricas recentes de transicoes de fase iSETAliquido-cristalinas / Micellar phases of the system sodium dodecyl sulfate (SLS)/water/decanol have been studied by X-ray scattering in isotropic I and liquid crystalline states, with emphasis on the 1-+hexagonal Ha and 1nematic Nc phase transitions. Study of the intermicellar peak position in the binary SIS/water system, taking into account relative volumes of amphiphile, shows that micelles are stable and slightly anisometric in concentrated I phases, with local close packing of spheroidal micelles. Micellar growth occurs only near the 1Ha transition. Analysis of the scattering curve I( q) for lower concentrations (up to 9 wt% SLS) shows that it is possible to obtain the distance distribution function p(r), in specific cases in which l(q) is dominated by a peak due to the inner micellar structure. Micellar anisometries v are deduced from Dmax values, with p(r)=O for r Dmax. It results v.: 1.5. The electron density distribution p(r) obtained from p(r) in these lower concentrations confirm the existence of micellar anisometry.

Este trabalho visa o estudo de elastômeros de uretano/uréia (PU/PBDO) e elastômeros de acetoxipropilcelulose (APC). No caso dos elastômeros de PU/PBDO, sintetizamos filmes com e sem a presença de grãos magnéticos orientados ou não na matriz elastomérica. Após o processo de síntese, algumas amostras de PU/PBDO com e sem as nanopartículas foram expostas à radiação ultravioleta por algumas horas. Diferentes técnicas foram utilizadas na análise estrutural e comportamento óptico e mecânico destes filmes, tais como, a técnica de ressonância magnética nuclear (RMN) convencional e de campo cíclico rápido, difração de raios X, ensaios de tensão x deformação, birrefringência óptica e microscopias óptica, de força atômica e de força magnética. Os resultados de RMN mostraram que a presença das nanopartículas na estrutura dos filmes de PU/PBDO enfraquece a dependência de T1 com a frequência de Larmor na região de interações inter-segmentos da curva de dispersão. Os módulos de Young das amostras de PU/PBDO não dopadas são maiores que os obtidos para as diferentes situações de amostras dopadas. O filme de APC é mais resistente e flexível que os diferentes filmes de PU/PBDO. Os resultados de raios X mostraram que ambos os filmes são compostos por uma rede reticulada e que o cisalhamento aplicado durante a síntese do filme, assim como, diferentes estiramentos aplicados em determinada direção da amostra, podem induzir uma certa orientação das moléculas em sua direção. Padrões de escala µm são observados em amostras de PU/PBDO, com e sem as nanopartículas magnéticas, quando suas superfícies são irradiadas com luz UV e depois aplicado um estiramento em qualquer direção da amostra. Isso indica que as ligações cruzadas induzidas pela luz UV ocorrem na presença das nanopartículas. Nas amostras de APC, o próprio cisalhamento aplicado ao filme, durante sua preparação, produz um padrão de escala µm em sua superfície. Além deste padrão de escala micrométrica, há formação de padrões de escala macroscópica que aparecem somente durante ou após o estiramento do filme ao longo da direção perpendicular ao cisalhamento. / This work aims the study of the urethane/urea (PU/PBDO) elastomerers and acetoxypropylcellulose (APC) elastomers. In the case of PU/PBDO elastomers, we synthesized films with and without the presence of oriented or not magnetic grains in the elastomeric matrix. After the synthesis process, some PU/PBDO samples with and without the nanoparticles were exposed to ultraviolet radiation for several hours. Different techniques were used in the structural analysis and mechanical and optical behavior of these films, such as, the technique of conventional and fast field cycling nuclear magnetic resonance (NMR), X-ray diffraction, stress x strain tests, optical birefringence and optical, atomic force and magnetic force microscopy. The NMR results showed that the presence of nanoparticles in the PU/PBDO film structure weakens the T1 dependence with the Larmor frequency in the region of inter-segment interactions of the dispersion curve. Young modules of the PU/PBDO undoped samples are larger than those obtained for the different situations of the doped samples. APC film is more resistant and flexible then different PU/PBDO films. The X-rays results showed that both films are composed of a cross-linked network and that the casting applied during the film synthesis, as different stretches applied in a given direction in the sample can induce a certain orientation of the molecules in their direction. Patterns of the µm are observed in PU/PBDO samples, with and without the magnetic nanoparticles, when their surfaces are irradiated with UV light and then applied a stretch in any direction of the sample. This indicates that cross-links induced by UV light occur in the nanoparticles presence. In APC samples, the actual casting applied to the film during its preparation, produces a pattern of µm scale on its surface. Besides this micron-scale pattern, there is formation of macroscopic patterns that appear only during or after film stretching along the direction perpendicular to the casting.

Polymer stabilized cholesteric liquid crystals (PSCLCs) provide many advantages over other electro-optical materials. The unique helical structure of the cholesteric liquid crystal (CLC) creates a natural gradient for light interacting across each CLC domain layer. Not only does the CLC helical structure greatly increase the bandwidth tuning and broadening range, it also allows CLCs to act as a polarizer, notch filter, reflector, and optical rotator all in one material. However, while many novel PSCLC materials have been created, little is understood about how complex initial system interactions affect final electro-optical (e-o) properties.1,2 In this work, the principal variables affecting PSCLC blue shift electro-optical behavior have been determined through structural analysis and measurement of electro-optical properties. Typical PSCLC materials must meet both formulation and photopolymerization processing requirements to display blue shift e-o properties. Threshold photoinitiator concentrations (0.5-1.5 wt%) and morpholine containing group concentrations (0.25-1.0 wt%) were both shown to be primary factors, along with sufficient UV exposure time (10-30 min) and light intensity (500 mW/cm2, 365 nm), for PSCLC blue shift bandwidth tuning/broadening to occur. Morpholine was initially identified as a component of photoinitators Irgacure 369 and 907 and was proven to increase PSCLC ion density altering LC-polymer network interactions with several proposed theories included later in this work. The use of an appropriate morpholine containing LC monomer to directly incorporate morpholine into the LC-polymer network was shown to greatly improve PSCLC sample stability. Through the results of this research we successfully induced blue shift e-o behavior in a previous red shift only PSCLC using only 30% of the UV exposure that a model PSCLC blue shift sample required while extending the blue shift broadening range over threefold (from 75 nm to 250 nm). The fundamental understanding and design of PSCLC systems described herein serves as a starting point for engineering PSCLC materials with specific and desirable electro-optical properties.

Incorporating nanotechnology into polymers has tremendous potential to improve the functionality and performance of polymer materials for use in a wide range of biomedical and industrial applications. This research uses lyotropic liquid crystals (LLCs) to control polymer structure on the nanometer scale in order to improve material properties. The overall goal of this research is to establish fundamental methods of synthesizing polymers with controlled nanostructured architectures in order to understand and utilize useful property relationships that result from the organized polymer morphologies. This work aims to establish a fundamental understanding of the reaction conditions needed to control polymer nanostructure and determine the benefits of organized polymer network structures on mechanical and transport properties. The synthesis of nanostructured polymers for improved material performance has utilized LLCs and photopolymerization kinetics to direct polymer structure. Self-assembled LLC phases provide a useful template that may be used as a photopolymerization platform to control polymer morphology on the nanometer size scale. Photopolymerization kinetics were used as a tool to examine the thermodynamics and phase structure evolution that occurs during the polymerization reaction. Additionally, several methods were developed to control polymer morphology and prevent loss of LLC order that can occur during polymerization. LLCs were also used to generate nanocomposite polymers with two distinct polymer networks to impart improvements in material properties. Other useful property relationships including increases in mechanical integrity, greater diffusive transport, and larger water uptake were established in this research. Finally, the LLC templating process was applied to solve performance problems associated with stimuli-sensitive polymer materials. Dramatic improvements in the response rate, dynamic range, and mechanical properties were achieved using LLCs and photopolymerization to control polymer nanostructure. This work has established fundamental tools that can be used to understand and control the evolution of polymer structure during the polymerization reaction in order to improve polymer properties. Ultimately, the enhanced properties generated by the nanostructured polymer network can be used to improve the functionality of polymers.

Il est actuellement bien connu que les molécules non sphériques peuvent former des mésophases (ou cristaux liquides), c'est-à-dire des phases dont les propriétés sont intermédiaires entre celles des liquides et celles des cristaux. La mésophase la plus connue est la phase nématique. Il s'agit d'une phase caractérisée par une distribution aléatoire des centres de masse des molécules, mais dans laquelle l'orientation des molécules présente une direction préférentielle, désignée par un vecteur unité appelé le directeur du nématique. Une telle phase possède donc la fluidité d'un liquide tout en présentant, tel un cristal, une biréfringence. C'est cette dernière propriété qui est exploitée dans les applications technologiques, principalement dans les dispositifs d'affichage. Dans un tel dispositif, le liquide nématique est contenu dans une cellule (il y a une cellule par pixel), et son directeur est manipulé à l'aide d'un champ extérieur, électrique ou magnétique. Pour une bonne compréhension du fonctionnement de ce dispositif, il est essentiel de connaître le profil du directeur à travers la cellule en l'absence de champ extérieur. Dans le cadre de ce travail, nous avons étudié un nématique torsadé, c'est-à-dire dont le directeur décrit une hélice à travers la cellule. Ce profil est déterminé principalement par les propriétés d'ancrage du liquide nématique sur les parois solides de la cellule. En effet, celles-ci peuvent posséder une direction d'ancrage privilégiée, qui favorise l'alignement du directeur dans une direction particulière. Nous avons considéré ici le cas de directions d'ancrage planaires, c'est-à-dire que le directeur est dans le plan des parois. Alors que l'ajout de parois identiques dans le système induit toujours une non-uniformité spatiale dans la densité du nématique (en comparaison avec un nématique en coeur de phase), l'utilisation de directions d'ancrage différentes induit une non-uniformité orientationnelle dans le directeur du nématique; dans notre cas une torsion. C'est principalement ce profil de directeur torsadé qui nous intéresse ici. L'objectif général de ce travail consiste donc à étudier les propriétés d'ancrage d'une phase nématique confinée et torsadée, d'une part par une théorie microscopique (théorie de la fonctionnelle de la densité), et d'autre part sur le plan de simulations de Monte Carlo, en particulier dans le cas où les molécules ont la forme de disques (discotiques).

Discotic liquid crystals (DLCs), which consist of disc-like molecules, are known to be able to form nematic and columnar mesophases through self-assembly. Because of the high electric charge mobility in one-dimension, DLCs are found to have uses in making electronic and photonic devices, such as organic light emitting diode, photovoltaic and molecular wires. In order to achieve better performance of these applications, it is essential to obtain the desired alignment of the DLCs. The purpose of this study is to investigate the stacking of disk-like molecules and to control their alignment. The materials used in the present studies are HDBP-8 and LC10. In this thesis, we will show that the stack of disk-like molecules is strongly influenced by temperature. We will also discuss how the molecules stacking is influenced by surface free energy. The disk-like molecules tend to stack with face-on when the surface free energy of the substrates is high. On a surface with lower surface free energy, molecules tend to stack with edge-up. In the latter part of the research, substrates are specially treated to have different surface free energies, and molecular stack on these substrates is observed.

In recent years, integrated circuit technology has spawned the development of many low cost and high performance microprocessors and microcontrollers. With these devices, there is an increasing interest in the implementation of distributed control networks, utilizing microprocessors in the control nodes. In this work, a low-cost liquid crystal display (LCD) unit utilizing a Hitachi HD44780 controller was designed to provide a visual display node for COLAN (Control Oriented Local Area Network). An Intel 8051 microprocessor was used to provide control services for the display and also to provide a communication interface to the network. The users in the COLAN network can remotely display and easily control the panel of LCDs by sending commands to the display control nodes through the local area network. This capability is especially useful to provide instructions to operators, provide synchronization for human interaction, and for use in locating faults in the system. The software necessary for implementing display and control functions has been developed, including file transfer and text transfer between supervisory nodes and display nodes. This software fits within the task structure associated with the COLAN communication protocols. The display node has been designed, fabricated, and tested in a system involving multiple COLAN nodes and a personal computer host. The emphasis of this work is in the implementation of the display control node and HD44780 controller including hardware and software developments. The hardware work includes designing and interfacing, and the software work includes high level and low level language programming. / Graduation date: 1993

At the age of multi-media, portable electronic devices such as mobile phones, personal digital assistant and handheld gaming systems have increased the demand for high performance displays with low cost production. Inkjet printing color optical filters (COF) for LCD applications seem to be an interesting alternative to decrease the production costs. The advantage of inkjet printing technology is to be fast, accurate, easy to run and cheaper than other technologies. In this master thesis work, we used various disciplines such as optical microscopy, rheology, inkjet printing, profilometering and colorimetry. The specific aim of the thesis was to investigate the feasibility of using company-A pigment formulation in inkjet production of COF for active matrix LCD applications. Ideal viscosity parameters were determined from 10 to 20mPa·s for easy inkjet printing at room temperature. The red pigments used are fully dispersed into the solvent and present an excellent homogenous repartition after printing. Thickness investigations revealed that the printed COF were equal or slightly thicker than typically manufactured ones. The colorimetry investigations demonstrated color coordinates very close to the NTSC red standard. LED backlighting seems to be a valuable solution to combine with the printed COF regarding to the spectrum and color analysis. The results on this thesis will increase the understanding of inkjet printing company-A pigments to produce COF for LCD applications.

In this study, we demonstrated a flexible cholesteric liquid crystal display using polymerization induced phase separation (PIPS) on a single substrate. Cholesteric liquid-crystal displays (ChLCDs) provide with color reflection owing to their periodic helical layer, without any optic device like polarizer or color filter. We discussed the influence of surface treatment and process conditions on PIPS, and improve the reflectivity of single substrate Ch-LC display from 9.05% to 19.27%.

This work demonstrates the pretilt angle controllable photo-alignment effect in nanoparticles and azo-dye doped liquid crystal film. Followed by increasing the absorbed azo-dye, the vertical alignment induced by nanoparticles of polyhedral oligomeric silsesquioxanes (POSS) can be changed from high pretilt to low pretilt angle. Competition between the homogeneously aligned azo-dye and POSS-induced spontaneous vertical alignment domain generated the variable pretilt angle. The pretilt angle is a function of the pumping intensity and can be controlled continuously within the range of 0¢X~90¢X. With the sufficient absorption of photo excited azo-dye, The POSS induced vertical alignment can be switch to homogeneous alignment. The pretilt angle and surface energy are also examined to confirm the alignment effect. Both nanoparticles and azo-dye induced vertical and homogeneous alignment are non contact methods, and suitable for low temperature plastic process.