Thesis (M. App. Sc.)--Carleton University, 2004. / Includes bibliographical references (p. 91-96). Also available in electronic format on the Internet.

Thesis (M.SC.) - Carleton University, 2007. / Includes bibliographical references. Also available in electronic format on the Internet.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 255-263). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D. in Chemistry)--Vanderbilt University, Dec. 2006. / Title from title screen. Includes bibliographical references.

No description available.

Les polymères synthétiques sont largement utilisés aujourd’hui comme implants prothétiques. Malheureusement, ces implants sont invisibles en imagerie par résonance magnétique IRM. La visualisation de ces implants est une nécessité afin d'obtenir des informations concernant leur fixation dans le corps et leur situation post-opératoire.Un des défis est alors de fixer un agent de contraste sur l'implant médical. Pour cet objectif, un premier polymère va être fonctionnalisé avec un agent de contraste de manière covalente, puis on le dépose par enduction sur la surface de la prothèse. Les polymères seront fonctionnalisés par polymérisation radicalaire et par chimie "click". Dans une première étape, le poly(méthacrylate de méthyle-co-méthacrylate de propargyle) avec un faible rapport molaire en méthacrylate de propargyle (F <10%) est préparé par copolymérisation radicalaire du méthacrylate de méthyle et du méthacrylate de propargyle. Dans une deuxième étape, l'agent de contraste sera greffé avec par réaction de chimie « click » sur le poly(méthacrylate de méthyle) porteur de fonctions propargyles (PMMA-co-PMA). Sur ce squelette polymérique, un nouveau agent de contraste à base de gadolinium sera greffé. Le polymère obtenu sera déposé sur une maille de polypropylene commercial par la technique de l'aérographie et la maille sera évaluée pour l'IRM visualisation sur un7T instrument. Des tests de cytotoxicité et de cytocompatibilité seront effectuées pour évaluer l'utilisation de cet agent de contraste dans des applications biomédicales.En même temps, les techniques d'imagerie de fluorescence gagnent aussi en popularité . Pour cela, le même polymère synthétisé (PMMA–co-PMA) sera fonctionnalisé avec différents précurseurs fluorescents: anthracène , fluorescéine, complexe d’europium. / Synthetic polymers are widely used nowadays as prosthetic implants. Unfortunately, these implants are invsisble by magnetic resonance imaging (MRI). The visualization of these implants is a necessity in order to gain information concerning their fixation in the body and post-operation fate. One of the challenges is then to fix a contrast agent on the implant. Thus the objective is to develop novel strategies for the long-term visualization of prosthetic implants by MRI. For this goal, a polymer will first be functionalized with a contrast agent in a covalent way, and then it will be deposited by coating on the surface of the prosthesis. Polymers will be functionalized by free radical polymerization followed by “click chemistry. In a first step, poly(methyl methacrylate-co-propargyl methacrylate) with low molar ratio in propargyl methacrylate (F< 10 %) will be prepared by free radical copolymerization of methyl methacrylate with propargyl methacrylate. In a second step, a novel gadolinium based contrast agent will be grafted by click chemistry onto the propargylated poly(methyl methacrylate) (PMMA-co-PMA) polymer. The obtained polymeric contrast agent will be spread on a commercial polypropylene mesh by the airbrushing technique and the mesh will be assessed for MRI visualization on a 7T instrument. Cytocompatibility and cytotoxicity tests will be performed to evaluate the use of this contrast agent in biomedical applications.At the same time, fluorescence imaging techniques are also gaining popularity. For this, the same synthesized polymer (PMMA-co-PMA) will be attached to different fluorescent precursors: anthracene, fluoresceine, and europium complex.

As propriedades de rugosidade superficial e microdureza são reconhecidas como propriedades muito relevantes no que concerne ao tratamento com prótese total removível, estando associadas ao desgaste da prótese e à sua predisposição à colonização por microrganismos. A proposição deste estudo foi realizar uma análise longitudinal e comparativa, destas duas propriedades, entre uma nova resina acrílica (Vipi Block Gum) para bases de próteses totais removíveis, implementada na tecnologia CAD-CAM, e duas resinas acrílicas termopolimerizáveis, sendo uma convencional (Vipi Cril Plus) e outra polimerizada por ação de micro-ondas (Vipi Wave), antes e após a aplicação de sucessivos ciclos de envelhecimento térmico por temociclagem, de modo a investigar a existência de uma correlação entre o processo de polimerização e o desempenho do material. Para isto, foram confeccionados um total de 60 corpos de prova com formato quadrangular com dimensões de 12x12x3mm, sendo destinados 20 corpos de prova para cada material. Para cada resina, 10 corpos de prova foram destinados ao teste de microdureza Knoop (KHN) e os outros 10 corpos de prova foram submetidos ao teste de rugosidade superficial (Ra-m). As análises dos corpos de prova, para ambos os experimentos, foram realizadas em quatro estágios distintos. As primeiras leituras foram realizadas após imersão dos materiais em água deionizada a 37ºC durante 24 horas (T1), com subsequentes análises após a aplicação de 500 ciclos (T2), 1000 ciclos (T3) e 3000 ciclos (T4) de termociclagem, com temperaturas de 5ºC a 55ºC com duração de 60 segundos para cada banho. Na avaliação estatística, a comparação das médias entre os grupos de resinas foi realizada com o teste de análise de variância (ANOVA) de um critério sendo, seguido do teste de Tukey. Para a comparação interna de cada grupo, em relação ao estágio de termociclagem, foi utilizado um ANOVA de medidas repetidas. O nível de significância adotado foi de 5%. Não houve diferença estatisticamente significante, na comparação intragrupos e intergrupos, em relação à rugosidade superficial (p>0.05). Na análise comparativa da microdureza entre os grupos, foi observada diferença estatisticamente significante nas análises em T1 e T2, com a resina Vipi Block obtendo valores superiores às outras resinas (p=0.00). Em T3, observou-se uma redução significativa da microdureza de todas as resinas, sendo mais pronunciada na resina Vipi Block Gum, tendo esta sido estatisticamente superior apenas em relação à Vipi Wave (p=0.01). Em T4 foi observado um aumento significativo na resina Vipi Cril Plus, com diferença estatisticamente significante (p>0.05) em relação às outras resinas. Na análise interna de cada grupo, foram observadas interações estatisticamente significantes em todas as resinas (p<0.05). A resina Vipi Block Gum teve sua microdureza drasticamente reduzida em T3, mantendo-se similar em T4, sendo significativamente inferiores (p<0.05) aos valores obtidos em T1 e T2. A resina Vipi Cril Plus sofreu uma acentuada redução na comparação em T1 em relação a T3 (p=0.021). Em T4, tornou-se estatisticamente superior a todos os outros períodos (p<0.05). A resina Vipi Wave sofreu redução significativa de T2 para T3 (p=0.01). Semelhantemente, obteve um aumento em T4, tornando-se estatisticamente superior a T3 (p=0.01). / Superficial roughness and microhardness are considered as extremely relevant properties which directly affects treatments with complete removable dentures, being them related to wear, and to the vulnerability of these prostheses to be colonized by microorganisms. The objective of this study was to perform a longitudinal analysis of these properties, making a comparison between a new CAD-CAM denture base acrylic resin (Vipi Block Gum), a conventional heat-polymerized and a microwave-polymerized resins, before and after the application of successive thermocycling cicles, in order to investigate a possible higher performance presented by the Vipi Block Gum resin. Sixty quadrangular shaped specimens with dimensions of 12x12x3mm were made and were equally divided between the three resins. For each material, 10 specimens were destined to the surface roughness analysis (Ra-m) and the other 10, for the Knoop microhardness (KHN) evaluation. The firsts analyses were performed after a 24-hour period of immersion in distilled water at 37ºC (T1), with subsequent analyses after 500 cicles (T2), 1000 cicles (T3) and 3000 cicles (T4) of thermocycling, with temperatures ranging from 5ºC to 55ºC and with 60 seconds of immersion, for each temperature. The statistical analysis, for the intergroup comparison, was done by applying a one-way analysis of variance (ANOVA) test, seconded by Tukeys posthoc test. For the intragroup analysis, a repeated measures ANOVA was applied. A significance level of 5% was adopted for both analyses. There were no significant differences for both intragroup and intergroup comparisons concerning the superficial roughness (p>0.05). The intergroup microhardness analyses showed significant differences at T1 and T2 (p=0.00), with higher values presented by the Vipi Block Gum resin when compared to the other groups. At T3, it was noticed a significant reduction for all materials, although it was more pronounced in the Vipi Block Gum resin, with this group having higher values than the Vipi Wave group (p=0.01). The comparison at T4 showed significant higher values presented by the Vipi Cril Plus in relation to the other groups (p<0.05). The intragroup analyses exhibited statistical significant differences for all materials (p<0.05). Vipi Block Gum resin suffered a significant decrease on its microhardness at T3, which remained similar at T4. However, these values were significant below (p<0.05) the ones obtained at T1 and T2. Vipi Cril Plus group showed a significant decrease at T3 in comparison with T1 (p=0.021). However, it increased significantly at T4 having statistical higher values than all other periods (p<0.05). Vipi Wave group suffered an expressive decrease at T3 in comparison with T2 (p=0.01). It also had an increase on its microhardness at T4, with statistical higher values than the ones observed at T3 (p=0.01).

Nanocompósitos de PMMA/ argila montmorilonita foram obtidos por fotopolimerização in situ. O metacrilato de metila foi polimerizado na presença de argilas modificadas usando Tioxantona (TX) e etil 4-(dimetilamino) benzoato (EDB) como sistema fotoiniciador. As argilas montmorilonitas SWy-1 modificadas, SWy-1-C8 e SWy-1-C16, foram preparadas pela troca de íons com brometo de octiltrimetilamônio (C8) e brometo de hexiltrimetilamônio (C16), respectivamente. A difração de raios-X indicou que os compósitos de PMMA/argila podem ter estruturas intercaladas ou esfoliadas, ou mesmo uma mistura de estruturas em camadas esfoliada e parcialmente intercalada. A estrutura de cada nanocompósito depende da concentração de argila e do solvente utilizado na preparação. A influência da concentração de argila organofílica, natureza do solvente e tipo de argila nas propriedades térmicas e mecânicas foi estudada por análise termogravimétrica e análise dinâmico-mecânica. Todos os nanocompósitos preparados em acetonitrila exibiram melhora da sua estabilidade térmica, principalmente devido à interação entre a argila e o polímero que é maximizada através da estrutura da argila esfoliada. No caso do PMMA e nanocompósitos sintetizados em etanol, a estabilidade térmica do polímero e nanocompósitos foi praticamente a mesma, uma vez que a estrutura da argila é predominantemente do tipo intercalada. Na velocidade de polimerização observou-se que os fatores que mais influenciaram foram a concentração de argila e o tipo de solvente. A argila proporciona a formação de microambientes que estabilizam o estado excitado do iniciador formando mais radicais livres e consequentemente aumentando a velocidade polimerização. A utilização da acetonitrila, a qual é um melhor solvente para o PMMA proporcionou massas molares menores. A degradação foto-oxidativa dos nanocompósitos de PMMA/ argila foi investigada utilizando cromatografia de exclusão de tamanho (SEC). Foram encontradas evidências de que o PMMA e nanocompósitos degradam por cisões aleatórias de cadeias. A polidispersidade aumentou após a irradiação e o coeficiente de degradação de PMMA puro é de até seis vezes maior do que para os nanocompósitos. O efeito sobre os coeficientes de fotodegradação da concentração de argila, tipo argila (argila modificada por agentes tensoativos com diferentes comprimentos de cadeias de alquílica) e o solvente utilizado para a dispersão de argila orgânica, também foram estudados. / Montmorillonite clay/PMMA nanocomposites were obtained by in situ photopolymerization. Methyl methacrylate was polymerized in the presence of modified clays using thioxanthone (TX) and ethyl 4-(dimethylamino) benzoate (EDB) as photoinitiating system. The SWy-1 montmorillonite modified clays, SWy-1-C8 and SWy-1-C16, were prepared by ion exchange with octyltrimethylammonium bromide (C8) and hexyltrimethylammonium bromide (C16), respectively. X-ray diffraction indicated that clay/PMMA composites have intercalated or exfoliated structures, or even a mixture of exfoliated and partially intercalated structure layers. The structure of each particular nanocomposite depends on the clay loading and the solvent used for the preparation.The influences of organoclay loading, solvent nature and clay type on thermal and mechanical properties were studied by thermogravimetric analysis and dynamic mechanical analysis. All the nanocomposites prepared in acetonitrile exhibited improvement in their thermal stability, mainly due to the interaction between the clay and the polymer which is maximized by the exfoliated clay structure. In the case of PMMA and nanocomposites synthesized in ethanol, the thermal stability of polymer and nanocomposites remained practically the same once the clay structure is predominantly of the intercalated type. It was observed that the factors that most influenced the polymerization rate were the concentration of clay and type of solvent. The clay provides the formation of microenvironments that stabilizes the excited state of the initiator forming free radicals and consequently increasing the polymerization rate. The use of acetonitrile, which is a better solvent for PMMA gave the lowest molar weight. The photooxidative degradation of clay/PMMA nanocomposites has been investigated using size exclusion chromatography (SEC). Evidence was found that PMMA and composites degrade by random chain scissions. The polydispersity increases after irradiation and the degradation rate coefficient for pure PMMA is up to 6 times larger than that for the composites. The effect on the photodegradation rate coefficients of the clay content, clay type (clay modified by surfactants with different lengths of alkyl chains) and solvent used for dispersion of organic clay were also studied. The relationship of these parameters on the photodegradation process was statistically evaluated using a two-level factorial design.

by Lui Bong Chun, Richard. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references. / Abstract / Acknowledgment / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background for the Project --- p.1 / Chapter 1.1.1 --- Interests in Blue-Green Laser --- p.1 / Chapter 1.1.2 --- Progress of Blue-Green Laser --- p.2 / Chapter 1.2 --- The Aim of the Project --- p.3 / Chapter 1.3 --- Overview the Remaining Parts of this Thesis --- p.4 / Chapter 1.4 --- References --- p.6 / Chapter Chapter 2 --- Sum Frequency Generation --- p.8 / Chapter 2.1 --- Introduction --- p.8 / Chapter 2.2 --- Sum Frequency Generation --- p.8 / Chapter 2.2.1 --- Theoretical Background for Sum Frequency Generation --- p.9 / Chapter 2.2.2 --- The Coupled Wave Equations for SFG --- p.13 / Chapter 2.2.3 --- Phase Matching Considerations --- p.16 / Chapter 2.3 --- References --- p.18 / Chapter Chapter 3 --- Cerenkov Radiation --- p.19 / Chapter 3.1 --- Introduction --- p.19 / Chapter 3.2 --- The Properties of Cerenkov Radiation by Using TM Mode --- p.21 / Chapter 3.2.1 --- Refractive Index Notation --- p.23 / Chapter 3.2.2 --- Fundamental Wave TM Guides Mode --- p.23 / Chapter 3.2.3 --- Second Harmonic TM Radiation Mode --- p.24 / Chapter 3.2.4 --- Efficiency of SHG --- p.25 / Chapter 3.3 --- Simplified Model Analysis of Cerenkov Radiation in TE Mode --- p.29 / Chapter 3.4 --- Simulation --- p.33 / Chapter 3.4.1 --- Modeling the LiNb03 --- p.33 / Chapter 3.4.2 --- Modeling an Asymmetric Slab Waveguide ´ؤPMMA doped with MNA on Fused Quartz --- p.37 / Chapter 3.4.3 --- Modeling a Symmetric Slab Waveguide ´ؤPMMA doped with MNA on Fused Quartz --- p.42 / Chapter 3.5 --- References --- p.47 / Chapter Chapter 4 --- Ellipsometry --- p.49 / Chapter 4.1 --- Introduction --- p.49 / Chapter 4.2 --- General Principles --- p.49 / Chapter 4.3 --- Basic Operation --- p.50 / Chapter 4.4 --- The Optical Constants of the Bulk Materials --- p.51 / Chapter 4.5 --- Calculation the Refractive Index of the Substrates --- p.53 / Chapter 4.6 --- Ellipsometric Theory for the Thin Film --- p.57 / Chapter 4.7 --- Measurement the Refractive Index and the Thickness of the Thin Film --- p.59 / Chapter 4.7.1 --- Data --- p.62 / Chapter 4.7.2 --- Discussions --- p.73 / Chapter 4.8 --- Calculation the Refractive Index of the thin Film by Considering as a Bulk Material --- p.78 / Chapter 4.9 --- References --- p.80 / Chapter Chapter 5 --- Prism Coupling --- p.81 / Chapter 5.1 --- Introduction --- p.81 / Chapter 5.2 --- Coupling of a Plane Wave --- p.82 / Chapter 5.3 --- Numerical Approach for the Calculation of the Coupling Efficiency --- p.85 / Chapter 5.4 --- Experiment --- p.88 / Chapter 5.4.1 --- Experimental Setup --- p.88 / Chapter 5.4.2 --- Experimental Result and Discussions --- p.90 / Chapter 5.5 --- References --- p.92 / Chapter Chapter 6 --- Conclusion --- p.93 / Chapter Chapter 7 --- Future Plans --- p.96 / Chapter 7.1 --- Simplified Model of Corona Poling --- p.96 / Chapter 7.2 --- Advanced Models of Poling --- p.98 / Chapter 7.2.1 --- Slab Waveguide --- p.98 / Chapter 7.2.2 --- Channel Waveguide --- p.99 / Chapter 7.3 --- References --- p.100 / Chapter Appendix 1 --- Materials' Descriptions --- p.A-l / Chapter A.1.1 --- 2-Methyl-4-Nitoaniline --- p.A-1 / Chapter A.1.2 --- Poly ( Methyl Methacrylate ) --- p.A-3 / Chapter A.1.3 --- References --- p.A-4 / Chapter Appendix 2 --- Fabrication Procedures --- p.A-5 / Chapter A.2.1 --- Cleaning the Apparatus --- p.A-5 / Chapter A.2.2 --- Cleaning the Substrate --- p.A-5 / Chapter A.2.3 --- Thin film Fabrication --- p.A-5 / Chapter A.2.4 --- Thin Film Removal --- p.A-6 / Chapter A.2.5 --- References --- p.A-6 / Chapter Appendix 3 --- Alpha Step --- p.A-7 / Chapter A.3.1 --- Introduction --- p.A-7 / Chapter A.3.2 --- Experimental Setup --- p.A-8 / Chapter A.3.3 --- Experimental Results --- p.A-9 / Chapter A.3.3.1 --- Thin Film of PMMA without Dopant --- p.A-9 / Chapter A.3.3.2 --- Thin Film of PMMA doped with MNA --- p.A-19 / Chapter A.3.4 --- Discussions --- p.A-27 / Chapter A.3.5 --- References --- p.A-28 / Chapter Appendix 4 --- Scanning Electron Microscope --- p.A-29 / Chapter A.4.1 --- Scanning Electron Microscope --- p.A-29 / Chapter A.4.2 --- Reference --- p.A-30 / Chapter Appendix 5 --- Gaussian Beam & Coordinate System Transformation --- p.A-31 / Chapter A.5.1 --- Gaussian Beam in a Homogeneous Medium --- p.A-31 / Chapter A.5.2 --- Transformation of the Coordinate Systems --- p.A-32 / Chapter A.5.3 --- Reference --- p.A-32 / Chapter Appendix 6 --- Waist Size Measurement of Gaussian Beam --- p.A-33 / Chapter A.6.1 --- Waist Size Measurement of Gaussian Beam --- p.A-33 / Chapter A.6.2 --- References --- p.A-34 / Chapter Appendix 7 --- Quasi Phase Matching --- p.A-35 / Chapter A. 7.1 --- Introduction --- p.A-35 / Chapter A.7.2 --- Basic Concept of QPM --- p.A-36 / Chapter A.7.3 --- References --- p.A-38 / Chapter Appendix 8 --- Program Listing --- p.A-41 / Chapter A.8.1 --- Program Listing ( Chapter 3 ) --- p.A-41 / Chapter A.8.1.1 --- Program 3.1 (transcendental.m ) --- p.A-41 / Chapter A.8.1.2 --- Program 3.2 (linbo3.m) --- p.A-42 / Chapter A.8.2 --- Program Listing ( Chapter 4 ) --- p.A-45 / Chapter A.8.2.1 --- Program 4.1 ( ellipsometry.m ) --- p.A-45 / Chapter A.8.3 --- Program Listing ( Chapter 5 ) --- p.A-47 / Chapter A.8.3.1 --- Program 5.1 ( parameter.m ) --- p.A-47 / Chapter A.8.3.2 --- Program 5.2 ( coupling.m ) --- p.A-49 / Chapter A.8.3.3 --- Program 5.3 ( v_3_amp.m ) --- p.A-50 / Chapter A.8.3.4 --- Program 5.4 ( input_profile.m ) --- p.A-51

Orientador: Keizo Yukimitu / Resumo: Com a crescente populacional a demanda pelos polímeros aumentou significativamente, levando assim a pesquisas cientificas visando adequar materiais as nossas necessidades. O PMMA ou acrílico é muito utilizado em nosso cotidiano, sendo um material muito versátil com aplicabilidade em diversos setores. O intuito deste trabalho foi realizar a produção de um filme de acrílico [Poli(metil-metacrilato)] isento de bolhas e transparente, a qual tivesse uma repetibilidade. Foi realizada a dopagem com terras raras, sendo o Óxido de Érbio e o Óxido de Itérbio escolhidos como dopantes em diferentes concentrações de gramas/mol por gramas/mol (0 % referência, 5 %, 10%, 15% e 20 %). Logo após foi feita a caracterização dos filmes, determinando o índice de refração das amostras utilizando o Interferomêtro de Michelson com laser He-Ne (vermelho) de comprimento de onda de 632,8 nm. Notamos que o índice de refração do PMMA na amostra de referência aumentou gradativamente com as dopagens, o laser diodo na cor verde de comprimento de onda de 532 nm também foi utilizado e os resultados demostraram comportamentos similares. A Espectroscopia no Infravermelho por Transformada de Fourier (FTIR) foi realizada, observando o aparecimento de picos característicos dos elementos dopantes nas amostras e que esses picos aumentavam conforme a concentração de dopagem aumentava. A Difração de Raios-X (DRX) nos mostrou a incidência picos de cristalinidade referentes aos elementos dopantes em contraste com o espec... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: With the growing population demand for polymers has increased significantly, leading to scientific research aimed at adapting materials to our needs. PMMA or acrylic is widely used in our daily lives, being a very versatile material with applicability in several sectors. The purpose of this work was to produce an acrylic film [Poly (methyl-methacrylate)] which had a repeatability. Rare earth doping was performed, with Erbium Oxide and Ytterbium Oxide chosen as dopants in different concentrations of grams / mole per gram / mole (0% reference, 5%, 10%, 15% and 20%). After the characterization of the films, determining the refractive index of the samples using the Michelson Interferometer with He-Ne (red) laser of wavelength of 632.8 nm, we noticed that the refractive index of the PMMA in the sample of reference period increased gradually with doping, the green diode laser wavelength of 532 nm was also used and the results demonstrated similar behaviors. Fourier Transform Infrared Spectroscopy (FTIR) was performed, observing the appearance of characteristic peaks of the dopant elements in the samples and that these peaks increased as the doping concentration increased. X-ray Diffraction (XRD) showed us the incidence of crystallinity peaks relative to the dopant elements in contrast to the normal PMMA spectrum demonstrating the insertion of the rare earths into the matrix structure. / Mestre