• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1
  • 1
  • Tagged with
  • 4
  • 4
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 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.
1

Noncovalent Functionalization of Latex Particles using High Molecular Weight Surfactant for High-Performance Coatings

Zheng, Lei 20 August 2019 (has links)
The expected outcome of this project is to develop a general strategy to functionalize dispersions, by noncovalent adsorption of HMW surfactants, ultimately for applications such as hydrophobic coatings with high hiding power and hardness, improved mechanical properties via pigment-latex interactions, improved substrate adhesion or improved freeze-thaw stability. So far, we have produced poly (methyl methacrylate-co-butyl acrylate) latexes in the presence of HMW surfactants via emulsion polymerization and demonstrated stronger adsorption of HMW surfactants on particle surface than sodium dodecyl sulfate (SDS). In addition, we have developed surfactant-free latexes, poly (methyl methacrylate-co-butyl acrylate-co-methacrylic acid), as models for post functionalization with high molecular weight surfactants. The successful transfer of surfactants onto particle surface from liquid crystals was indicated by the increase in zeta potential and confirmed via chemical shifts variation in 1H NMR spectra. Additionally, the HMW surfactants were used for dispersing hydrophobic inorganic particles, such as hydrophobic carbon black, in aqueous phase, providing an indication of the general applicability and versatility of our approach.
2

Cannabidiol : exploring new synthetic pathways for late-stage functionalization

Rigaut, Sophie 08 1900 (has links)
L’intérêt grandissant suscité par les propriétés thérapeutiques exhibées par les cannabinoïdes a motivé la naissance du projet décrit dans ce mémoire de maîtrise. La synthèse efficace de différents cannabinoïdes est devenue essentielle afin de pouvoir mieux comprendre les mécanismes régulant les propriétés médicales de ces composés ainsi que pour promouvoir le développement de nouveaux traitements médicamenteux. Le cannabidiol est d’intérêt particulier en raison des propriétés anti-inflammatoires, et anticancéreuses exhibées par cette molécule. Ce projet vise à explorer différentes routes permettant la fonctionnalisation du cannabidiol en phase avancée dans le but de faciliter l’accès aux dérivés de ce produit naturel. La première partie de ce mémoire se concentre sur le développement d’une voie de synthèse permettant la fonctionnalisation d’un précurseur du cannabidiol en utilisant le 1,3-diméthoxybenzène, un produit de départ abordable et commercialement disponible. L’approche proposée comporte six étapes et s’appuie sur une réaction de Diels-Alder pour générer l’adduit bicyclique du cannabidiol. Plusieurs routes ont été explorées pour obtenir la fonctionnalisation de ce précurseur, à savoir une borylation de Hartwig-Miyaura et une bromination du cycle aromatique. La deuxième partie de ce projet se concentre sur la fonctionnalisation du cannabidiol en phase avancée en s’appuyant sur la fonctionnalité de l’amide de Weinreb. Ces travaux ont abouti au développement d’une voie de synthèse efficace et durable pour la production de l’olivetol, un fragment clé pour la production à grande échelle de cannabidiol dans l’industrie pharmaceutique. Cette méthode se base sur une approche en quatre étapes s’appuyant sur un amide de Weinreb en utilisant un produit de départ abordable, l’acide 3,5-dimethoxy benzoïque. La synthèse de l’amide de Weinreb puis de la cétone correspondante, suivie d’une réduction de Wolff-Kishner, et enfin la démethylation du substrat ont permis d’obtenir le produit désiré. La versatilité de cette approche tolère une fonctionnalisation variée de la molécule, permettant la synthèse potentielle de divers dérivés de l’olivetol. / The increasing interest around the therapeutic possibilities offered by cannabinoids was the motivation for the project described in this Master’s thesis. The efficient synthesis of various CBs has become critical to deepen the understanding of the mechanisms behind the medical properties of cannabinoids as well as for the development of novel drug treatments. Cannabidiol is of particular interest as the molecule exhibits anti-inflammatory, and anticarcinogenic properties. This work aims to explore different routes to enable the late-stage functionalization of cannabidiol in order to easily access derivatives of the natural compound. The first part of this work focuses on developing a route enabling the functionalization of the cannabidiol precursor utilizing the affordable and commercially available starting material 1,3-Dimethoxybenzene. The proposed six-step approach relies on a Diels-Alder reaction to generate the bicyclic adduct of cannabidiol. Several routes were then explored to obtain the functionalization of the precursor namely a Hartwig-Miyaura borylation and a bromination of the aromatic ring. The second part of this project focuses on the functionalization of cannabidiol relying on the Weinreb amide functionality. This work led to the development of an efficient and sustainable route for the synthesis of olivetol, a key fragment for the large-scale production of cannabidiol within the pharmaceutical industry. The method relies on a four-step approach relying on a Weinreb amide synthesized using the affordable 3,5-Dimethoxybenzoic acid. The synthesis of the Weinreb amide followed by the formation of the corresponding ketone, subsequent Wolff-Kishner reduction, and finally demethylation of the substrate allowed to generate the desired product. The versatility of the approach allows for variations in functionalization, enabling potential formation of various olivetol derivatives.
3

Hyperbranched conjugated polymers: an investigation into the synthesis, properties and postfunctionalization of hyperbranched poly(phenylene vinylene-phenylene ethynylene)s

Kub, Christopher 07 July 2010 (has links)
There are two general ways to introduce functionalities into a polymeric structure: functionalization of the monomeric units before polymerization and postfunctionalization of the preformed polymer. Building libraries of polymers with different functionalities can be completed with significantly less effort by the second method, as each postfunctionalization of a single batch of polymeric backbone can involve as little as one synthetic step. One method of building a polymeric backbone for postfunctionalization involves the synthesis of hyperbranched conjugated polymers (HCPs) from AB2 monomeric units. A polymer formed from n AB2 monomeric units should contain n reactive B groups, which act as sites of functionalization. Utilizing this principle, two different hyperbranched poly(phenylene vinylene-phenylene ethynylene) scaffolds were synthesized and studied in both their inherent properties and functionalization. The first HCP synthesized was compared against a monomeric cruciform model and a linear polymer with a similar structure. The hyperbranched polymer has red-shifted absorption and emission in comparison to the cruciform model and linear polymer. The HCP quenches paraquat more efficiently than the linear polymer by a factor of about two, suggesting a greater rate of energy transfer. The functionalization of HCPs was studied; iodine groups decorating the HCPs were replaced with terminal alkynes by Pd-catalyzed coupling, providing a library of 24 differently functionalized HCPs. Elemental analyses of the postfunctionalized polymers show nearly complete substitution of the iodine groups. The postfunctionalized polymers show increased fluorescence compared to the original iodine decorated polymers, due to the loss of the heavy atom effect inducing iodine groups. The emissions of the postfunctionalized polymers in solution show a strong dependence on the groups attached to the conjugated structures, with emission maxima ranging from 505 nm to 602 nm; quantum yields range from 0.7% to 25%. Solid-state emission studies show stronger and more red-shifted spectra compared to emissions observed in solution.
4

Recyclage et revalorisation de films de PET / PVDC par extrusion réactive à basse température / Recycling and reuse of PET / PVDC films by reactive extrusion at low temperature

Chabert, Mickaël 25 March 2013 (has links)
Une voie originale de recyclage des films de PET / PVDC est proposée par leur transformation chimique avec des alcoxydes de titane par procédé d'extrusion réactive à l'état solide. Les réactions d'échanges entre ces composés organo-métalliques et le PET ont été mises en oeuvre à des températures entre 250 et 280° C à l'échelle du laboratoire et ont permis de segmenter les chaînes de PET, en de petits oligomères avec des températures de fusion basses, sur des temps de réaction très courts de l'ordre de quelques minutes. Ces oligomères peuvent être post-fonctionnalisés avec des diols. Le transfert technologique de ces réactions d'échange à l'échelle de l'extrudeuse bi-vis pilote a été optimisé afin de permettre la transformation des films de PET / PVDC à des températures comprises entre 160 et 180 °C pour ne pas dégrader le PVDC. Les alcoxydes de titane permettent de stabiliser les dégagements d'acide chlorhydrique (HCl) lors de la dégradation thermique de ce polymère halogéné. La revalorisation de ces oligomères dans différents systèmes polyuréthanes a ensuite été étudiée et a démontré la compatibilité des oligomères de PET avec ces matrices avec l'amélioration de certaines propriétés physiques et mécaniques / An original way for recycling PET / PVDC films is proposed by their chemical transformation with titanium alkoxydes by reactive extrusion process in the solid state. The exchange reactions between these organo-metallic species and the PET were carried out at temperatures between 250 and 280°C at laboratory scale and they have allowed to shorten the PET's chains, in short oligomers with low melting temperatures, in a range of reaction time of few minutes. These oligomers could be post-functionalized with diols. The technologic transfert of these exchange reactions to the twin screw extruder scale was optimized in order to transform PET / PVDC films at temperatures between 130 and 180°c without degrading the PVDC. The titanium alkoxydes allow to stabilize the release of hydrochloric acid (HCl) during thermal degradation of this halogenated polymer. The reuse of these oligomers into different polyurethane systems were then studied and demonstrated the compatibility of PET oligomers with these matrix with improvements of some physical and mechanical properties

Page generated in 0.1437 seconds