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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

Zwillingspolymerisation in Gegenwart von Übergangsmetallen

Schliebe, Christian 08 September 2015 (has links) (PDF)
Die vorliegende Arbeit befasst sich mit der Inkorporation von Metall-/ Metalloxidnanopartikeln in organisch-anorganischen Hybridmaterialien, dargestellt durch Zwillingspolymerisation. Dabei wurden verschiedene Lösungsansätze bearbeitet. Zum einen wurden Metalcarboxylate oder Metallocene verwendet, zum anderen konnten durch Variation der anorganischen Komponente des Zwillingsmonomeres entsprechende Nanopartikel erzeugt werden. Um die Nanopartikel stabilisierenden Eigenschaften, der aus Zwillingspolymeren zugänglichen porösen Kohlenstoffmatrix zu erhöhen sollten mittels Zwillingspolymerisation N-Donoren eingeführt werden Neben der Inkorporation von Nanopartikeln wurden auch Silber und Goldnanopartikel in einer porösen Kohlenstoffmatrix verkapselt. Dabei wurde gezeigt, dass der Verwendete Templatdurchmesser einen entscheidenden Einfluss auf die späteren Hohlkugeln hat. Es konnte ebenso mit Hilfe von einfachen Benchmarkreaktionen die Zugänglichkeit und katalytische Aktivität der eingekapselten Nanopartikel nachgewiesen werden. Es wird gezeigt, dass durch Verwendung von Triphenylphosphan-stabilisierten Silber(I)-carboxylaten eine Funktionalisierung von Zwillingspolymeren möglich ist. Außerdem sind aus dem so modifizierten Hybridmaterialien nach Karbonisierung sowie dem Herauslösen der anorganischen SiO2-Komponete entsprechende mikroporöse, silberhaltige Kohlenstoffmaterialien zugänglich, während durch oxidativen Abbau der organischen Polymermatrix mesoporöse mit Ag-Nanopartikeln infiltrierte SiO2-Materialien dargestellt werden können. Es werden spezifische Oberflächen von 1034 m2/g (Kohlenstoff) und 666 m2/g (SiO2) erhalten. Das Wachstum der Silbernanopartikel konnte mittels Temperatur abhängiger Röntgenpulverdiffraktometrie beobachtet werden, und es wurde gezeigt, dass ein Wachstum erst während des Karbonisationsprozesses einsetzt. Mittels der HAADF-STEM-Technik wurden die gebildeten Nanopartikel im porösen Kohlenstoff bzw. SiO2 nachgewiesen, dabei liegen die Nanopartikel-durchmesser unterhalb von 5nm. Darüber hinaus konnte eine Vielzahl von neuen Zwillingsmonomeren dargestellt und charakterisiert werden. Darunter finden sich Zirkonium- und Hafnium-haltige Verbindungen, die analog der bekannten Si-Zwillingsmonomere ein ähnliches Polymerisationsverhalten zeigen und aus den resultierenden Hybridmaterialien poröse Oxide mit spezifischen Oberflächen unter 100 m2/g erhalten wurden. Eine Ausnahme bildet hierbei die SBS-Analoge Hafniumverbindung zur Phasenseparation während der Zwillingspolymerisation neigt, ebenso konnte für diese Verbindung kein vollständiger Umsatz erzielt werden. Durch Copolymerisation dieser neuen Zr- und Hf-haltigen Monomeren mit 2,2‘-Spirobi[4H-1,2,2-benzodioxasilin] wurden ZrO2- und HfO2-reiche SiO2-Mischoxide dargestellt. Dabei wurde das thermische Verhalten dieser Mischoxide mittels DSC weiter untersucht und es zeigte sich das ab 1000°C die ZrO2 sowie HfO2-Phasen beginnen zu Kristallisieren. Die so gebildeten hochkristallinen Nanopartikel konnten mittels TEM beobachtet werden. Ein weiteres erhitzen auf über 1200 °C führte dann noch zur Kristallisation der SiO2-Matrix. Ein weiteres Beispiel zur Synthese von oxidische Nanopartikeln mittels Zwillingspolymerisation wurde am ersten Metallocenhaltigen Zwillingsmonomer gezeigt. Dieses war aus der Reaktion von SiCl4 und Ferrocenylmethanol zugänglich. Neben der standardmäßigen Charakterisierung wurde auch die elektrochemischen Eigenschaften hin untersucht und dabei zeigte anders als es zu erwarten war eine Redox-Separation zwischen den einzelnen Ferrocengruppen. Weiterführende spektroelektrochemischen Experimente zeigten, dass diese Aufspaltung durch elektrostatische Abstoßung hervorgerufen wird. Das Zwillingspolymerisationsverhalten wurde zunächst mittels DSC untersucht und dabei konnte bei 210 °C eine exotherme Reaktion beobachtet werden, die mittels TG-MS als Kondensationsreaktion identifiziert wurde. Aufgrund dieser Ergebnisse konnte das Ferrocen-haltige Zwillingsmonomer thermisch polymerisiert werden. HAADF-STEM Abbildungen zeigten den typischen Aufbau eines Zwillingspolymeres, jedoch ist die Anzahl der zu beobachtenden Siliziumdioxidnanocluster geringer als bei bekannten Si-basierten Monomeren. Durch Copolymerisation mit 2,2‘-Spirobi[4H-1,2,2-benzodioxasilin] konnte dieser Nachteil ausgeglichen werden und nach karbonisierung und herauslösen der SiO2-Komponente bzw. Oxidation wird poröser Kohlenstoff (858 m2/g) bzw. Siliziumdioxid (555 m2/g) erhalten. Die Natur der eingebettet Eisenhaltigen Nanopartikel konnte mithilfe von Mössbauerspektroskopie untersucht werden. Dabei wurde im Kohlenstoffmaterial eine Mischung aus Fe2O3 und Fe3C gefunden während im SiO2 aufgrund der oxidierenden Bedingungen, während der Darstellung, von Fe2O3-Nanopartikeln ausgegangen wird. Die durchgeführten Mössbauerexperimente lieferten auch Indizien dafür, dass die gebildeten Nanopartikel sehr klein sind, dies wurde auch mittels HAADF-STEM bestätigt, jedoch kann kein genauer Zahlenwert fehlerfrei angegeben werden. Die geringe Größe spiegelt sich auch im magnetischen Verhalten der porösen Materialien wieder so verhält sich das SiO2 Material superparamagnetisch während der Kohlenstoff paramagnetisch ist. Abschließend konnten Pyrrol-basierte Siliziumalkoxide durch die Reaktion von SiCl4 und den entsprechenden Alkoholen dargestellt werden. Das Zwillingspolymerisation verhalten wurde mittels DSC charakterisiert. Dabei konnten wie schon zuvor beschrieben exotherme Reaktionen detektiert werden und diese liegen deutlich unter den Initiierungstemperaturen der bekannten Zwillingsmonomere (140 °C für N-Methylpyrrol und 93 °C für Pyrrol). Mittels TG-MS konnten auch hier Kondensationsreaktionen identifiziert werden. Daraufhin wurde die Hybridmaterialien aus den thermisch induzierten Polymerisationsversuchen beider Verbindungen untersucht. Es zeigte sich, dass das N-Methyl substituiertes Monomer sich nur in schlechten Ausbeuten polymerisieren lässt während das Pyrrolderivat ausgezeichnete Ausbeuten liefert. Auch die spezifischen Oberflächen sind mit bis zu 633 m2/g beträchtlich höher als mit vergleichbaren und bekannten Zwillingsmonomeren erzielt werden können. Auch zeigen sich beim einfachen Pyrrolbasierten Monomer Unterschiede zwischen thermischer und säure initiierter Zwillingspolymerisation. Während im ersten Fall hauptsächlich das 2-5-Substituierte Polymer erhalten wird kommt es bei säure Initiierung auch zur Bildung einer N-Alkyliertenspezies. Aus den Dargestellten Hybridmaterialien konnten poröse Kohlenstoffe mit Stickstoffgehalten zwischen 5.0-9.1 % erhalten werden. Auch hier zeigte sich das die Kohlenstoffe abgeleitet von dem N-methylierten Pyrrol einen höheren Stickstoffgehalt aufweisen als die aus der unmethylierte Spezies.
142

Synthesis of polymer-polymer hybrids by miniemulsion polymerisation and characterisation of hybrid latex

Udagama, Ravindra 05 October 2009 (has links) (PDF)
The objectives of work presented in this thesis are to understand droplet and particle formulation processes in order to make useful polymer-polymer hybrids in aqueous dispersions and use our fundamental understanding of these processes to: 1. Improve monomer conversion as much as possible. 2. Understand impact of these processes on hybrid film properties. Specific case studies of interest under commercially feasible conditions (i.e. solids content of 50wt %) were done based on two systems namely alkyd-acrylic and polyurethane-acrylic. Miniemulsification, miniemulsion polymerisation and characterisation of hybrid latex, chemical incorporation of alkyd and polyurethane to acrylic monomers were studied in detail. We have been able to successfully synthesise and characterise hybrid latex of about 100nm in particle diameter and high solids content (50wt %) to be used in coating and adhesive applications
143

Monomer recovery from nylon carpets via reactive extrusion

Bryson, Latoya G. 28 March 2008 (has links)
The catalytic depolymerization/pyrolysis of nylon 6 and 66 were investigated with the prospect of helping to curb the amount of carpet landfilled. Thermogravimetric analysis was used to determine which catalysts (and their nylon/catalyst ratio) were most suited for the depolymerization. By adding bases, the onset of degradation for some bases was 100 aC lower than that of the pure nylons. Potassium hydroxide and sodium hydroxide were found to be the most effective catalysts at a catalyst ratio of 100:1 of nylon 6 and nylon 66 to catalyst, respectively. After determining the most efficient catalyst, kinetic models/parameters from the TGA data were determined. These parameters were used in a reactive extrusion model for depolymerizing nylon 6 in carpet. Data from the model was then used to do cost analysis for the process. It was found that to get a Present Value Ratio greater than 1, the flow rate has to be greater than or equal to 500 lb/hr. At even higher flow rates up to the model¡¦s limit (1500 lb/hr), the Net Present Value shows that this process is economically viable. Extrusion of a 100:1 ratio of pure N6 and KOH was done in a 30 mm counter-rotating non-intermeshing twin screw extruder. The material collected from the vents of the extruder was tested with a gas chromatograph- mass spectrum (GC-MS) in tandem. There was only one significant peak from the GC and the primary molecular weight on the MS was 113, the molecular weight of caprolactam. This shows that the process could be profitable and require little purification if done industrially.
144

Synthèse de copolymères d'architecture contrôlée à motifs acide phosphonique : étude de leurs propriétés superplastifiantes dans des pâtes cimentaires / Synthesis of phosphonic acid-functionalized copolymers with controlled architecture : evaluation of their superplasticizer properties in cement paste

Seiler, Lucie 05 May 2017 (has links)
Les polymères fonctionnalisés par des groupements phosphonates ont un fort potentiel applicatif comme superplastifiants dans les pâtes de ciment. Des copolymères à blocs fonctionnels ont été synthétisés par polymérisation RAFT/MADIX afin d'accéder à des polymères de masse molaire, d'architecture et de composition contrôlées. Le monomère principalement utilisé a été l'acide vinylphosphonique (VPA). L'amélioration de la cinétique ainsi que la conversion finale lors de la polymérisation du VPA a été un des principaux objectifs de la thèse, en vue de synthétiser des copolymères diblocs PEG-PVPA. Ensuite des copolymères à blocs ont été synthétisés à l'aide d'un disulfure de xanthate. Ce nouveau procédé a permis d'obtenir des structures de copolymères à blocs plus complexes à bas de MPEGMA et de VPA, dont la synthèse à partir d'un agent de contrôle RAFT conventionnel aurait été relativement ardue. Des essais ont été menés sur des pâtes cimentaires afin d'évaluer les propriétés des différents copolymères. Les effets de l'adsorption des copolymères à blocs sur la mise en œuvre du béton ont été évalués et comparés à des superplastifiants phosphonatés commerciaux. / Phosphonic acid-functionalized polymers show great promise as superplasticizers in cement mixtures. Functional block copolymers were synthesized by RAFT/MADIX polymerization to obtain polymers of controlled molecular weight, architecture and composition. The principal monomer used was vinylphosphonic acid (VPA). The enhancement of the kinetics of VPA polymerization and the final yield was one of the aims of the thesis. Block copolymers were then synthesized using xanthate disulfide as a chain transfer agent. This new process enabled us to obtain complex structures that would be difficult to synthesize using a more conventional RAFT process. The effects of block copolymer adsorption on cement workability were assayed with reference to a commercially available phosphonated superplasticizer.
145

Estudo da adsorção de horseradish peroxidase (HRP) sobre superfícies planas e de sua atividade catalítica / Study on the adsorption of horseradish peroxidase (HRP) onto flat surfaces and its catalytic activity

Alliny Ferreira Naves 10 July 2008 (has links)
Este trabalho está dividido em duas partes: (i) estudo da adsorção da enzima horseradish peroxidase (HRP) sobre substratos planos (lâminas de Si/SiO2, filmes ASP/Si/SiO2, filmes CABads/Si/SiO2, filmes CABspin/Si/SiO2 e filmes CMCABspin/Si/SiO2) seguida de testes da atividade enzimática da HRP imobilizada sobre estes substratos e (ii) obtenção de oligômeros divinílicos mediada pela HRP. Na primeira parte, a imobilização da HRP sobre substratos planos foi estudada através de elipsometria, microscopia de força atômica (AFM) e medidas de ângulo de contato. As isotermas de adsorção da HRP sobre Si/SiO2, APS/Si/SiO2 e CABads/Si/SiO2 apresentaram um aumento contínuo da quantidade de material adsorvido ΓHRP em função da concentração da solução de enzima até atingir um patamar de adsorção no qual verificou-se a formação de uma monocamada de HRP adsorvida. Nestes casos, o processo de adsorção da HRP pode ser descrito pelo modelo de adsorção aleatória (RSA). Para filmes HRP/CABspin/Si/SiO2 e HRP/CMCABspin/Si/SiO2 observou-se adsorção cooperativa de moléculas de HRP e formação de multicamadas. A adsorção da HRP sobre Si/SiO2, filmes APS, CABads e CMCABspin é um processo irreversível. Ao contrário, HRP adsorve reversivelmente sobre filmes CABspin, fato evidenciado pelo decréscimo de ~30% na espessura dos filmes de enzima. A atividade catalítica dos filmes de HRP imobilizados sobre substratos planos foi verificada na reação de oxidação do ABTS. Os testes de atividade catalítica mostraram que os substratos com a HRP adsorvida podem ser reutilizados 3 vezes sem dessorção ou perda da atividade catalítica da enzima, com exceção dos filmes HRP/CABspin/Si/SiO2 que se tornam inativos após a primeira catálise. A condição de máxima atividade catalítica de HRP imobilizada foi correlacionada com grau de cobertura de ~55%. O emprego do monômero etileno glicol dimetacrilato (EGDMA) em reações de polimerização catalisadas por filmes HRP/Si/SiO2 ou pela HRP livre em solução à temperatura ambiente revelou a formação de partículas cristalinas com geometria poligonal. Com objetivo de compreender a formação das estruturas cristalinas, a segunda parte do trabalho focou a formação de oligômeros de EGDMA e trietileno glicol dimetacrilato (TEGDMA) em meio aquoso catalisada pela HRP na presença H2O2 a temperatura ambiente. Os oligômeros de EGDMA e/ou TEGDMA foram caracterizados por gravimetria, cromatografia de permeação em gel, espectroscopia vibracional na região do infravermelho e espectroscopia 1H RMN. A auto-associação dos oligômeros originou partículas cristalinas com ângulos retos, como evidenciado pelas imagens de microscopia eletrônica de varredura. As medidas de calorimetria exploratória diferencial e difração de raio-x confIrmaram a cristalinidade das amostras. Os oligômeros de EGDMA, TEGDMA e EGDMA-co-TEGDMA sintetizados na presença do sistema HRP-H2O2 apresentaram grupos vinila pendentes, boa solubilidade em clorofórmio e ponto de fusão bem definido, evidenciando pouca reticulação ou ciclização e mostrando que as propriedades catalíticas da HRP propiciam um ambiente reacional apropriado para produzir materiais poliméricos com novas características. / This work is divided into two parts: (i) study on the adsorption of the enzyme horseradish peroxidase (HRP) onto flat substrates (silicon wafers, ASP/Si/SiO2 films, CABads/Si/SiO2 films, CABspin/Si/SiO2 films, and CMCABspin/Si/SiO2 films) followed by enzymatic catalytic tests of HRP immobilized onto these substrates, and (ii) formation of divinyl-based oligomers mediated by HRP. In the first part, the HRP immobilization onto flat substrates was investigated by means of ellipsometry, atomic force microscopy (AFM), and contact angle measurements. Adsorption isotherms of HRP onto silicon wafers, APS/Si/SiO2, and CABads/Si/SiO2 presented the continuous increase of HRP adsorbed amount ΓHRP as a function of enzyme solution concentration until an adsorption plateau, which evidenced monolayer formation. In these cases, the HRP adsorption process can be described by the random sequential adsorption model (RSA). For HRP/CABspin/Si/SiO2 and HRP/CMCABspin/Si/SiO2 cooperative adsorption of HRP molecules and multilayer formation were evidenced. The HRP adsorption onto silicon wafers, APS, CABads, and CMCABspin films is an irreversible process. Contrarily, HRP adsorbed reversibly onto CABspin films, since desorption of ~30% could be detected. The catalytic activity of HRP films immobilized onto flat substrates was verified by oxidation reaction of ABTS. Catalytic tests showed that substrates with adsorbed HRP can be reused three times without desorption or catalytic activity lost, except for HRP/CABspin/Si/SiO2 films, which became inactive after first use. The emulsion polymerization of ethylene glycol dimethacrylate (EGDMA) in mediated by HRP/Si/SiO2 films or by free HRP at room temperature revealed the formation of crystalline particles with polygonal geometry. In order to understand the formation of such crystalline structures, the second part of this thesis focused on EGDMA and/or triethylene glycol dimethacrylate (TEGDMA) oligomers formation in aqueous medium catalyzed by HRP in the presence of H2O2 at room temperature. EGDMA and/or TEGDMA oligomers were characterized by means of gravimetry, gel permeation chromatography, infrared vibrational spectroscopy and 1H NMR spectroscopy. Self-assembling of oligomers led to right-angled crystalline particles, as evidenced by scanning electron microscopy images. Differential scanning calorimetry and X-ray diffractometry measurements ratified the samples crystallinity. EGDMA, TEGDMA and EGDMA-co-TEGDMA oligomers synthesized in the presence of HRP-H2O2 system presented pendant vinyl groups along the chains, good solubility in chloroform, and well defined melting point. These features evidenced few crosslinking or cyclization and revealed that the catalytic properties of HRP provide an appropriate environrnent for production of materials with new characteristics.
146

Efeito do tipo de monômero ácido  empregado em cimentos resinosos autoadesivos experimentais, nas propriedades físico-químicas do cimento e na sua resistência de união à dentina e à Y-TZP / Effect of acid monomer type used in experimental self-adhesive luting cements about physico-chemical properties and bond strength to dentin and Y-TZP

Pedro Paulo Albuquerque Cavalcanti de Albuquerque 03 June 2015 (has links)
Objetivos: o presente estudo teve como objetivo determinar a aplicabilidade e eficácia adesiva de diferentes monômeros ácidos quando aplicados em formulações de cimentos resinosos autoadesivos experimentais sob o grau de conversão, propriedades físico-químicas e resistência de união à dentina e à zircônia tetragonal policristalina estabilizada por ítrea (Y-TZP), após um período de 3 meses de armazenamento em água. Material: dois tipos de cimentos do tipo pasta-pasta foram formulados contendo monômeros convencionais UDMA, HEMA, BISGMA, TEGDMA e monômeros ácidos 2MP e GDMAP como matriz orgânica. Um grupo contendo apenas monômeros convencionais foi formulado como grupo controle. Os componentes canforoquinona/EDMAB e peróxido de benzoíla/DHPT foram empregados como sistema de ativação dual. O sal sódico do ácido benzenosulfônico 98% (BAS) foi incorporado nos grupos experimentais. Partículas de carga foram incorporadas na proporção ±55% em peso final. Método: A técnica de espectroscopia no infravermelho (FT-IR) foi empregada para análise do grau de conversão (n=3) imediato e após 24 h. A avaliação do pH (n=3) foi feita através do emprego de um equipamento medidor de pH. Os corpos de provas foram imersos em água destilada e o pH foi analisado de forma imediata e após 5 min, 24 h e 48 h. Os testes de sorção e solubilidade (n=6) e espessura de película (n=5) seguiram as recomendações da ISO 4049. A análise de resistência de união (n=12) foi realizada em dentina e Y-TZP, através do teste de cisalhamento em área reduzida após um protocolo de envelhecimento em água destilada por 3 meses. No caso da Y-TZP, metade dos espécimes receberam um tratamento superficial cojet (30 ?m), associado a aplicação de um agente de união silano. O padrão de fratura foi analisado com o auxílio de um estereomicroscópio. Resultados: O grupo controle (91,7%) e o grupo formulado com 2MP (92%) apresentaram superiores valores de grau de conversão em relação ao grupo GDMAP (77,7%). O pH dos grupos experimentais 2MP e GDMAP se apresentou mais ácido após 48 h em comparação ao grupo controle. Em contrapartida, esses grupos experimentais apresentaram uma maior sorção e solubilidade em relação ao grupo controle. A espessura da película formada foi semelhante em todos os grupos testados (p=0,266). Em dentina o grupo controle (27,0 MPa) e GDMAP (24,1 MPa) não apresentaram diferença estatística após 3 meses de estocagem. O grupo 2MP (13,7 MPa) apresentou resultados inferiores aos demais grupos. O tratamento de superfície empregado não foi capaz de manter ou de elevar os valores de resistência de união à Y-TZP após o período de envelhecimento em água. Todos os grupos experimentais apresentaram falhas precoces ou baixos valores de resistência de união após 3 meses, independente da presença ou não do tratamento de superfície. Conclusão: os grupos experimentais 2MP e GDMAP apresentaram resultados promissores. Entretanto, a adesão dos CRAs experimentais testados em Y-TZP ainda se apresenta frágil e instável. / Objectives: the purpose of this study was to evaluate the applicability and adhesive efficiency of different acid monomers utilized in formulations of experimental self-adhesive resin cement under degree of conversion, physico-chemical properties and bond strength to dentin and Y-TZP after 3 months aging period. Materials: two paste-paste luting agents were formulated containing UDMA, HEMA, BISGMA, TEGDMA and acid adhesive monomers 2MP and GDMAP as organic matrix. The control group was formulated containing only conventional monomers. Camphoroquinone/EDMAB and benzoyl peroxide/DHPT were used as dual activation system. BAS salt was incorporated into the experimental groups. Filler particles were added in a proportion of ±55% final weight. Method: Infrared spectroscopy technique (FTIR) was employed for degree of conversion analysis (n=3) immediately and after 24 hours. The pH assessment (n=3) was made using a pH meter. All the specimens were immersed in distilled water and pH assessment was performed immediately and after 5 min, 24 h and 48 h. Tests for sorption and solubility (n=6) and thickness (n=6) were carried out according to ISO 4049 recommendations. Bond strength analysis (n=12) was performed in dentin and Y-TZP through microshear after an aging 3 months protocol in distilled water. Regarding Y-TZP, half of the specimens were submitted to a cojet surface treatment (30 ?m) in association to silane bonding agent application. Fracture toughness standard was evaluated with the assistance of a stereomicroscope. Results: The control (91,7%) and 2MP (92%) groups presented higher degree of conversion than GDMAP group (77,7%). The 2MP and GDMAP experimental groups showed the highest pH compared to control group. In contrast, experimental groups showed a high hydrolytic degradation. The thickness of the formed film was similar among all the tested groups (p=0,266). Regarding the dentin, control and GDMAP groups had statistically similar bond strength (27,0 and 24,1 MPa respectively) after 3 months storage. While 2MP group (13,7 MPa) showed lower results compared the other groups. The surface treatment employed was not capable to maintain or elevate bond strength to Y-TZP results after the aging period in water. All experimental groups showed low bond strength values and even early failures after 3 months, regardless the surface treatment or its abscence. Conclusion: the experimental groups 2MP and GDMAP presented promising results. However, chemical adhesion to Y-TZP still remains weak and instable.
147

Síntese de monômeros siloxano-oxiranos para aplicação em Odontologia / Synthesis of siloxane-oxirane monomers for use in dentistry

Leal, Fernanda Barbosa 19 December 2012 (has links)
Made available in DSpace on 2014-08-20T14:30:15Z (GMT). No. of bitstreams: 1 Dissertacao_Fernanda_Barbosa_Leal.pdf: 806160 bytes, checksum: 37717162c453100433c520a8c9d199ef (MD5) Previous issue date: 2012-12-19 / The aim of this study was synthesize, characterize and photopolymerize an alternative monomers for use in dentistry. Three siloxane-oxirane monomers were synthesized and the products conversion was followed by Fourier-transform infrared spectroscopy. The products obtained were characterized by 1H and 13C NMR and evaluated for viscosity and refractive index. The polymerization was evaluated by formulating of two experimental photoinitiation systems wich varied for the presence of 1,2 ethanediol. A ternary system with camphorquinone (CQ), ethyl 4-dimethylaminobenzoate (EDAB) and diphenyliodonium hexafluorphosphate (DPI) was used as control. The degree of conversion was accessed by FTIR and DSC-PCA. The NMR confirmed the synthesis success with 75, 87 and 55% yield for the monomers synthesized. Moreover, the presence of 1,2 ethanediol increase the degree conversion of the siloxane-oxirane monomers. This study showed simple and effective way to synthesize siloxane-oxirane monomers with a high potential for application in dental materials / O objetivo deste estudo foi sintetizar, caracterizar e fotopolimerizar monômeros alternativos para aplicação em Odontologia. Três monômeros siloxano-oxiranos foram sintetizados e a conversão de produtos foi acompanhada por espectroscopia de infravermelho por transformada de Fourier. Os produtos obtidos foram caracterizados por 1H e 13C RMN e avaliados quanto à viscosidade e índice de refração. Para investigar a polimerização, dois sistemas experimentais de fotoiniciação foram formulados, variando quanto à presença de 1,2 etanodiol. Um sistema ternário composto por canforoquinona (CQ), 4-dimetilaminobenzoato (EDAB) e difeniliodonio hexafluorfostato (DPI) foi utilizado como controle. O grau de conversão foi obtido por FTIR e DSC-PCA. As análises de RMN confirmaram a obtenção dos produtos com 75, 87 e 55% de rendimento. Além disso, a presença de 1,2 etanodiol aumentou o grau de conversão dos monômeros siloxano-oxiranos. Este estudo demonstrou um método simples e eficaz para sintetizar monômeros siloxano-oxiranos com grande potencial para aplicação em materiais dentários
148

Synthèse et fonctionnalisation d'aldéhydes issus de la coupure d'esters gras insaturés / Synthesis and functionalization of aldehydes from unsaturated fatty esters cleavage

Louis, Kévin 15 November 2013 (has links)
La valorisation du carbone renouvelable joue un rôle croissant dans l'industrie chimique. Ces travaux rapportent l'utilisation d'huiles végétales comme matières premières en substitution de celles d'origine fossiles pour la synthèse de monomères bio-sourcés destinés à la production de polyesters ou de polyamides.La production du 9 oxononanoate de méthyle, comme molécule plateforme, à partir d'esters méthyliques d'huile de colza a été réalisée par coupure oxydante (ozonolyse) sans solvant à température ambiante, suivie d'une réduction des intermédiaires par hydrogénation catalytique sous pression de H2 et de Pd(5)/C. Ainsi, le rendement en aldéhyde-ester est de 92%. Ce procédé a été appliqué à la synthèse de molécules plateformes avec des longueurs de chaînes de 9 à 13 atomes de carbone. Une matière première renouvelable, des conditions de réaction douces, le recyclage du catalyseur et des co-produits non toxiques et valorisables ont permis de développer un procédé durable plus respectueux de l'environnement. La réduction de la fonction aldéhyde a été menée par hydrogénation catalytique, à 50°C dans le méthanol, pour former l'alcool-ester correspondant. Le nickel de Raney ainsi que le Pd(5)/C offrent des rendements en 9-hydroxynonanoate de méthyle supérieurs à 90 %, mais le premier catalyseur conduit à un temps de réaction plus court. L'amination réductrice de la fonction aldéhyde a été menée avec succès à partir de NH3 gazeux et de Pd(5)/C, à 50°C dans le méthanol, pour conduire majoritairement à la synthèse de l'amino-ester primaire. La quantité de NH3(g) influence la sélectivité et au moins trois équivalents sont nécessaires pour limiter la formation d'amino-ester. / A high interest has been devoted to the use of renewable carbon in the chemical industry. The goal of this work is the substitution of fossil oils by vegetable oils to synthesize bio sourced monomers for polyesters and polyamides production. The synthesis of methyl 9-oxononanoate as a platform molecule from fatty acid methyl esters of rapeseed oil was carried out in solvent free ozonolysis at room temperature. Intermediary ozonides was reduced to aldehydes by catalytic hydrogenation under H2 pressure and in the presence of Pd(5)/C catalyst giving a 92% carbonyl yield. This process was applied to a wide range of unsaturated esters with a chain length within 9 and 13 carbon atoms. This process allows the selective conversion of renewable materials to value added chemicals, in mild conditions and in the presence of a recyclable catalyst. Moreover, the co products are non toxic and valuable. Hydrogenation of aldehyde group was performed in the presence of methanol at 50°C under hydrogen pressure. Raney Nickel and Pd(5)/C exhibit a yield to methyl 9 hydroxynonanoate higher than 90%. Reductive amination of the aldehyde functional group was investigated with success in the presence of NH3(g) and Pd(5)/C at 50°C in methanol to produce primary amino ester. The amount of ammoniac is directly correlated to the selectivity of the reaction. As a consequence a minimum amount of 3 eq. of ammoniac is required to avoid the formation of secondary amino-ester.
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Développement de nouveaux monomères biosourcés à base d’Isosorbide et applications à la synthèse de matériaux à applications spécifiques / Development of new biosourced monomers based on Isosorbide and applications to the synthesis of materials with specific applications

Saadaoui, Asma 03 March 2017 (has links)
L'isosorbide et ses dérivés sont des diols chiraux issus de l'amidon de maïs. L'utilisation de ce dernier en tant que monomère pour l'élaboration de polymères s'est révélée efficace, ces derniers égalant les propriétés des polymères conventionnels. Dans le cadre de cette thèse, ces diols sont employés pour synthétiser de nouvelles plateformes des monomères biosourcés AA et AB à partir des 1,4 :3,6- dianhydrohexitols. La synthèse d'intermédiaires à base de dinitriles ou de mononitriles et leurs dérivés à partir des trois isomères ainsi que les résultats d'essais de polymérisation de l'un de ces monomères prometteurs ont été décrits. Le polymère obtenu a révélé semi-cristallin grâce à l'agencement stéréorégulier des monomères AB. Ce travail est aussi le premier à décrire l'utilisation des réticulants chiraux à base de 1,4 :3,6-dianhydrohexitols participant à la formation du réseau tridimensionnel pour l'élaboration de polymères à empreintes (MIP) biosourcés pour la détéction de la Méthyltestostérone (MT). Les polymères synthétisés par polymérisation par précipitation ont été caractérisés. Les propriétés de rétention ont été évaluées en mode batch par HPLC-MS/MS. Ces MIPs présentent de bonnes propriétés d'adsorption vis-à-vis la MT avec des facteurs d'empreinte supérieurs à 1 montrant l'efficacité de l'impression. Ces matériaux présentent une bonne capacité d'adsorption comparée à la littérature. Les polymères non imprimés (NIP) ont même montré des capacités d'adsorption supérieure aux MIP classiques. La capacité d'adsorption la plus élevée a été observée pour cMIP-Is à base d'isosorbide, pour les concentrations importantes (500 mg L-1). Les données expérimentales ont été étudiées selon les modèles d'adsorption de Langmuir et Freundlich pour interpréter les phénomènes d'adsorption. Ces cMIP développés ont été adaptés pour l'extraction de la méthyltestotérone sur phase solide (SPE). Une procédure d'extraction a été développée en menant au travers d'une optimisation complète finalisée par une application aux eaux usées / The isosorbide and its derivatives are chiral diols obtained from cornstarch. The use of the latter as a monomer for the development of polymers has proved to be effective. The diols match the properties of conventional polymers. As part of this thesis, the diols are used to synthesize new platforms of bio based AA and AB from the 1,4: 3,6 - dianhydrohexitols monomers. The synthesis of intermediaries based on dinitriles or mononitrilies and their derivaties starting from the three isomers as well as the test results from one of these promising monomers polymerization which have been described. The resulting polymer revealed semi-cristallin through stereoregulier AB monomers layout. This work is also the first to describe the use of the reticulants chiral at base of 1.4: 3, 6-dianhydrohexitols participating in the formation of three-dimensional network for the development of polymers to footprints (MIP) Excelsior for detection of Methyltestosterone (MT). The polymers synthesized by polymerization have been characterized by precipitation. The properties of retention were evaluated in batch mode by HPLC-MS/MS. These MIPs present good properties of adsorption towards the MT with factors of footprint greater than 1 showing the effectiveness of printing. These materials have a good ability of adsorption compared to literature. Unprinted polymers (PIN) have shown even greater adsorption capacity than the conventional MIP. The high adsorption capacity was observed in cMIP-Is based on isosorbide for the concentrations (500 mg L-1). The experimental data have been studied according to Langmuir and Freundlich adsorption models to interpret the phenomena of adsorption these developed cMIP have been adapted for the methyltestoterone on the phase of extraction (SPE) solid. An extraction procedure has been developed leading through a full optimization finalized by an application in wastewater
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Studies Of Moisture-induced Crosslinking in Some Novel Vinyl Ether-Maleic Anhydride Copolymers and Terpolymers And Synthesis And Characterization Of Hyperbranched Polyketals

Rema, B 03 1900 (has links) (PDF)
No description available.

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