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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.
51

Multifunctional Dendritic Scaffolds: Synthesis, Characterization and Potential applications

Hed, Yvonne January 2013 (has links)
The development of materials for advanced applications requires innovative macromolecules with well-defined structures and the inherent ability to be tailored in a straightforward manner. Dendrimers, being a subgroup of the dendritic polymer family, possess properties which fulfill such demands. They have a highly branched architecture with a high number of functional groups and are one of the most well-defined types of macromolecules ever synthesized. However, despite their well-defined nature and high functional density, traditional dendrimers commonly lack diverse chemical functionalities. Therefore, this thesis focuses on the synthesis of more complex dendritic materials to extend their tailoring capacity by introduction of dualfunctionalities for multipurpose actions. It covers the synthesis of dualfunctional dendrimers, dendritic modification of linear poly(ethylene glycol) polymers and cellulose surfaces, and the synthesis of linear dendritic hybrids. The building blocks enabling this synthesis, AB2C monomers, were also developed during this work. The orthogonal nature between click groups (azide, alkyne and alkene) and hydroxyl groups have efficiently been utilized for postfunctionalization by robust click chemistry and traditional esterification reactions. Furthermore, linear dendritic hybrids were synthesized, merging the properties of linear and dendritic macromolecules. The dendritic frameworks were tailored towards the production of bone fracture adhesives, novel biofunctional dendritic hydrogels, biosensors and micellar drug delivery vehicles. / Utveckling av material för avancerade applikationer kräver innovativa makromolekyler med väldefinierade strukturer och som kan skräddarsys på ett enkelt sätt. Dendrimerer är en undergrupp av dendritiska polymerer vars egenskaper uppfyller dessa krav. De har en mycket förgrenad arkitektur med många funktionella grupper och är en av de mest väldefinierade befintliga syntetiska makromolekylerna. Trots dess väldefinierade karaktär och höga funktionalitet saknar ofta traditionella dendrimerer multipla kemiska funktionaliteter. Denna avhandling fokuserar därför på syntesen av mer komplexa dendritiska material för att förbättra deras kapacitet att skräddarsys, detta görs genom att introducera fler funktionaliteter som kan utnyttjas för multipla ändamål . Avhandlingen redogör för syntesen av difunktionella dendrimerer, dendritiska modifikationer av polyetylenglykol och cellulosaytor samt syntes av traditionella dendritiska hybrider. Byggstenarna som möjliggör syntesen, AB2C monomerer, framställdes också under detta arbete. Den ortogonala karaktären mellan klick grupper (azid, alkyn och alkene) och hydroxylgrupper har utnyttjats effektivt för funktionaliseringar genom användande av robust ”Click”-kemi och traditionella esterifikationsreaktioner. Vidare tillverkades de linjära dendritiska hybrider för att kombinera egenskaperna hos både linjära och traditionella dendritiska polymerer i en och samma makromolekyl. Samtliga dendritiska strukturer skräddarsyddes för applikationer så som benlimmer, biofunktionella dendritiska hydrogeler, biosensorer och läkemedels-bärande miceller. / <p>QC 20130830</p>
52

Micro-Structuring of New Materials Combined with Electronic Polymers for Interfaces with Cells

Vastesson, Alexander January 2012 (has links)
Materials based on novel Off-Stoichiometry Thiol-Ene polymers, abbreviated OSTE, show promising properties as materials forlow cost and scalable manufacturing of micro- and nanosystems such as lab-on-chip devices. The OSTE materials have tunablemechanical properties, offer possibility for low temperature bonding to many surfaces via tunable surface chemistry, and can beused in soft lithography. Unlike the commonly used elastomer poly(dimethylsiloxane), PDMS, the OSTE materials have lowpermeability for gasses, are resistant to common solvents and can be more permanently surface modified.In this master’s thesis project, the OSTE materials have been evaluated with focus on compatibility with cells, possibility fornanostructuring using soft lithography and the use of OSTE as a flexible support for conducting polymers.Results from cell seeding studies with HEP G2 cells suggest that cells can proliferate on a low thiol off-stoichiometry OSTEmaterial for at least five days. The biocompatibility for this type of OSTE material may be similar to poly(styrene). However, highlevels of free thiol monomers in the material decrease cell viability considerably.By using soft lithography techniques it is possible to fabricate OSTE nanochannels with at least the dimensions of 400 nm x 15nm. Combined with the advantages of using the OSTE materials, such as low temperature bonding and possibility for stablesurface modifications, a candidate construction material for future development of systems for DNA analysis is at hand.OSTE can serve as a flexible support for an adsorbed film of a conducting polymer with the possibility for future applicationssuch as electronic interfaces in microsystems. In this project, a film of PEDOT:PSS with the electrical resistance of ~5 kΩ wascreated by adsorption to an flexible OSTE material. Furthermore, results suggest that it is possible to further optimize theconductivity and water resistance of PEDOT:PSS films on OSTE.
53

Regioselectivity In The Ene Reaction Of Singlet Oxygen With Cyclic Alkenes And Application Of Ene Reaction To Stereoselective Synthesis Of Carbaheptopyranose Derivatives

Dogan, Sengul Dilem 01 October 2010 (has links) (PDF)
In the first part of this thesis is related to the regioselectivity in ene reaction of singlet oxygen with cyclic alkenes. The photooxygenation of 1-methyl-, 2,3-dimethyl-, 1,4-dimethylcyclohexa-1,4-dienes, 1,2,3,4,5,8-hexahydronaphthalene (16) and 2,3,4,7-tetrahydro-1H-indene (17) which are readily available through Birch reduction, yielded the ene products. The formed endocyclic dienes were trapped by the addition of singlet oxygen to give corresponding bicyclic endoperoxy-hydroperoxides. In the case of 1-methylcyclohexa-1,4-diene (13) and 1,4-dimethyl-cyclohexa-1,4-diene (15), cis-effect determined the product distribution. Photooxygenation of 2,3-dimethylcyclohexa-1,4-dienes (14) gave mainly exocyclic olefin, which was attributed to the lowered rotational barrier of the methyl group and increased reactivity of the methyl groups. Photooxygeneation of 1,2,3,4,5,8-hexahydronaphthalene (16) and 2,3,4,7-tetrahydro-1H-indene (17) shows importance of the geometry of the allylic hydrogen in the ground state. In the second part of this thesis is related to the stereoselective synthesis of carbaheptopyranose derivatives. Two new carbaheptopyranoses, 5a-carba-6-deoxy-&alpha / -DL-galacto-heptopyranose (184) and 5a-carba-6-deoxy-&alpha / -DL-gulo-heptopyranose (185) have been prepared starting from cyclohexa-1,4-diene. The addition of dichloroketene to cyclohexa-1,4-diene followed by subsequent reductive elimination and Baeyer-Villiger oxidation formed the bicyclic lactone 188. Reduction of the lactone moiety followed by acetylation gave the diacetate 182b with cis-configuration. Introduction of additional acetate functionality into the molecule was achieved by singlet oxygen ene-reaction. The formed hydroperoxide 189 was reduced and then acetylated. The double bond in triacetate was further functionalized either by direct cis-hydroxylation using OsO4 or epoxidation followed by ring-opening reaction to give the hepto-pyranose derivatives 184 and 185.
54

Análise não suave e aplicações em otimização /

Costa, Tiago Mendonça de. January 2011 (has links)
Orientador: Geraldo Nunes Silva / Banca: Luis Antônio Fernandes de Oliveira / Banca: Yurilev Chalco Cano / Resumo: Neste trabalho, estamos interessados em apresentar uma abordagem relacionando a análise não suave com a otimização. Primeiramente, é realizado um estudo sobre conceitos da análise não suave, como cones normais, cone tangente de Bouligand, subdiferenciais proximal, estrita, limite e de clarke. Com esses conceitos exibimos uma série de resultados, por exemplo, uma caracterização par funções de Lipschitz, subdiferencais da soma, produto e máximo de funções semi-contínuas inferior, uma versão não suave dos multiplicadores de Lagrange, i.e., condições de primeira ordem para otimalidade de problemas de otimização não suaves. Também é feito um estudo sobre as condições de segunda ordem para otimalidade em problemas de otimização não suaves e para isso, foi necessário a apresentação de outros conceitos e propriedades como os de Hessiana generalizada, Jacobiana aproximada a Hessiana proximada. Após a apresentação desses resultados, é feita uma análise sobre dois Teoremas que fornecem, com abordagens distintas, condições suficiente de segunda ordem para problemas de otimização não suaves e este trabalho é finalizado com a aprsentação de um resultado que é considerado uma "unificação" desses dois Teoremas / Abstract: In this work we are interested in the presentation of an approach relating Nonsmooth Analysis to Optimization. First we make a study about concepts of nonsmooth analysis such as, normal cone, Bouligand's tangent cone, proximal, strict and limiting Subdiferential, as well as Clarke's Suddifferential. After these, we exhibit a series of results, for example, a characterization of Lipschitz functions, Subdifferential sum, product and maxium rules of lower semicontinuous functions and a nonsmooth version of Lagrange's multiplier rule, that is, a first order necessary condition of optimality for nonsmooth optimization problems. We also made a study about second order optimality conditions for nonsmooth optimization problems. In order to do that, it was necessary to present other concepts and properties about generalized Hessian, approximate Jacobian and approximate Hessian. After presenting these concepts and results, an analysis of two theorems that provide, with different approches, second order conditions for optimality for nonsmooth problems is made. Finally, this dissertation is completed with the exposition of a result that is considered a "unification" of these two theorems / Mestre
55

Valorisation du divinylglycol (DVG), dérivé du glycérol, pour la synthèse de polymères originaux / Valorization of glycerol-based divinylglycol towards the synthesis of original polymers

Bonnot, Léa 15 December 2017 (has links)
Dans le contexte du développement des bio-raffineries, le glycérol et ses dérivéssont des co-produits de l’oléochimie pour lesquels de nouvelles voies de valorisation doiventêtre trouvées. Cette thèse porte sur l’étude de la polymérisabilité d’un dérivé du glycérol, ledivinylglycol (DVG), monomère symétrique à 6 carbones qui possède un diol vicinal et deuxfonctions vinyliques. Dans ces travaux, la réactivité des fonctions hydroxyle et vinyliques duDVG dans des réactions de polycondensation et polyaddition a été investiguée. Dans unpremier temps, la synthèse de polyesters et de polyuréthanes a été réalisée par réaction duDVG avec des diesters biosourcés et des diisocyanates, respectivement. Les fonctionsvinyliques du DVG ont ensuite été mises à profit pour synthétiser des polymères originaux parpolymérisation par ADMET et addition thiol-ène. Enfin, des réseaux tridimensionnels époxyamineont été préparés par polymérisation entre une série de diamines et le DVG bis-époxydé,préalablement obtenu par oxydation des doubles liaisons. Ces différentes méthodes depolymérisation ont montré que les doubles liaisons du DVG étaient plus réactives que lesfonctions alcool et qu’un panel de polymères originaux pouvait être obtenu à partir de cesynthon bio-sourcé. / In the context of the development of bio-refineries, glycerol and its derivatives areco-products of oleochemistry for which new valorization routes must be found. This thesisdeals with the polymerizability study of a glycerol derivative, divinylglycol (DVG), asymmetrical C-6 monomer which bears a vicinal diol and two vinyl functions. In this work, thereactivity of the hydroxyl and vinyl functions of DVG in polycondensation and polyadditionreactions was studied. In a first step, the synthesis of polyesters and polyurethanes wascarried out by reaction of DVG with biosourced diesters and diisocyanates, respectively. Thevinyl functions of DVG were then used to synthesize original polymers by ADMETpolymerization and thiol-ene addition. Finally, three-dimensional epoxy-amine networkswere prepared by polymerization between a series of diamines and the bis-epoxidized DVG,previously obtained by oxidation of the double bonds. These different methods ofpolymerization showed that DVG double bonds were more reactive than the alcohol functionsand that a panel of original polymers could be obtained from this bio-sourced synthon.
56

Immobilized Bis-Indenyl Ligands for Stable and Cost-Effective Metallocene Catalysts of Hydrogenation and Polymerization Reactions

Simerly, Thomas Max 15 August 2012 (has links) (PDF)
Reactions of catalytic hydrogenations and polymerizations are widely used in industry for manufacture of fine chemicals, pharmaceuticals, and plastics. Homogeneous catalysts for the processes that have low stability and their separation is difficult. Therefore, the development of new highly active and stable catalysts for hydrogenations and polymerizations is a necessity. The objective of this research was the development of a strategy for immobilization of heterogeneous metallocene catalysts. First, a methodology of immobilization of bis-indenyl ligands on the surface of mesoporous silica gel was designed. Four bis-indenyl ligands containing functionalized tethers of various lengths with terminal alkene groups were synthesized. All bis-indenyl ligands were immobilized on the surface of mesoporous functionalized silica gel by two methods: hydrosilylation and thiol-ene coupling of the double bond. After comparing the results, the second strategy was chosen as more efficient. The materials can be used further as intermediates for synthesis of supported metallocene catalysts.
57

Triazine-based adhesive : An adherence study on clinically used metal surfaces

Romson, Tomas January 2018 (has links)
When a material is adhered onto a specific surface it is relevant to know how to make thematerial stay on the surface. By investigating different primers to use with a triazine-basedadhesive, further improvements to using the adhesive on metals can be achieved. This studyfound that an adhesive of (2,4,6-trioxo-1,3,5-triazinane-1,3,5-triyl)tris(ethane-2,1-diyl)tris(3-mercaptopropanoate) (TEMPIC) and 1,3,5-triallyl-1,3,5-triazinane-2,4,6-trione(TATATO) adhered to titanium and stainless steel, two clinically used metal surfaces. Itfurther found that between a phosphonic acid primer, a biomimetic catechol primer and acommercially available silane primer the phosphonic acid primer gave the best adhesion.These results could be because of a higher amount of crosslinking for the phosphonic acidprimer. For further testing increased pH and increased amount as well as increasedhydrolysation time for the catechol and silane primers respectively is suggested. Shearstrength testing was used to determine the adhesion strength. The shear strength testswere done with conditioning in phosphate buffer saline (PBS) solution for 24h beforehand
58

Novel Modifications of Styrene-Butadiene and Isoprene Rubber

Schmitz, Nathan David 14 November 2022 (has links)
No description available.
59

Pericyclic and related rearrangements for the synthesis of nitrogen heterocyclic ring systems

Zhurakovskyi, Oleksandr January 2013 (has links)
The thesis describes synthesis and reactions of allene azides tethered to various functional groups and the application of the discovered cascade transformations towards the synthesis of radianspene J model system. Chapter 1 covers reactions of simple allene azides containing alkyl and cycloalkyl substituents. Thermal rearrangements of these substrates delivered isocyanides and azadienes via the proposed azatrimethylenemethane (ATMM) intermediates. On the other hand, vinylidenecyclopropanes (VDCPs) gave dramatically different products, as described in Chapter 2. A phenyl-substituted VDCP was transformed into an unstable polycyclic compound by a divinylcyclopropane rearrangement. Chapter 3 discusses allene azides tethered to furan, N-substituted pyrroles, and E- and Z-dienes. Depending on the structure of the starting material, products of formal (3+4)- or (2+3)-cycloaddition were formed. Finally, an application of the discovered cyclisation cascade towards total synthesis is described in Chapter 4. A model system of radianspene J was assembled using a key transannular cycloaddition of a macrocyclic allene.
60

Synthèse de copolymères thermosensibles par polymérisation radicalaire contrôlée RAFT : caractérisation et étude de leur interaction avec des protéines / Synthesis of thermoresponsive copolymers by RAFT polymerization : characterization and study of their interaction with proteins

Ho, The Hien 19 September 2012 (has links)
Ce travail de thèse porte sur la synthèse de (co)polymères thermosensibles présentant une fonctionnalité azlactone par polymérisation radicalaire contrôlée RAFT pour l’ancrage de biomolécules. Trois stratégies différentes ont été étudiées. La première stratégie a consisté en la synthèse d’un nouvel agent de transfert permettant d’obtenir des polymères thermosensibles à fonctionnalité azlactone en position . La seconde approche a permis d’introduire la fonctionnalité azlactone en position ω de copolymères thermosensibles via la combinaison de la polymérisation RAFT et de l’addition de Michaël « thiol-ène ». La dernière stratégie a conduit à des copolymères thermosensibles à fonctionnalité azlactone en position latérale par copolymérisation RAFT de la 2-vinyl-4,4-diméthylazlactone avec d’autres monomères. Enfin, la réactivité de ces copolymères thermosensibles pour l’ancrage d’une protéine modèle (lysozyme) a été mise en évidence. / The synthesis of well-defined azlactone-functionalized thermoresponsive copolymers was performed using the RAFT polymerization and their interaction with primary amines and proteins was studied. Three different strategies have been developed. The first strategy was based on the synthesis of a novel azlactone-functionalized chain transfer agent which was used to target well defined  azlactone-functionalized thermoresponsive polymers. In the second approach, ω-azlactone-terminated thermoresponsive copolymers were prepared by a combination of RAFT polymerization and “thiol ene” Michaël’s addition. In the last strategy, RAFT copolymerization of 2-vinyl-4,4 dimethylazlactone with other monomers has been performed to target well-defined azlactone functionalized copolymers. Finally, the reactivity of such reactive thermoresponsive copolymers was successfully demonstrated by bioconjugation with a model protein (lysozyme).

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