Teses / dissertações sobre o tema "MADIX controlled radical polymerization"
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1
Simms, Ryan W. "Living/controlled Polymerization Conducted in Aqueous Based Systems". Thesis, Kingston, Ont. : [s.n.], 2007. http://hdl.handle.net/1974/700.
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Miguel-Arricau, Sophie. "Corrélation structure/propriété de polymères à base d'acrylamide pour des applications en récupération assistée des hydrocarbures (RAH)". Electronic Thesis or Diss., Pau, 2022. https://theses.hal.science/tel-04010751.
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La connaissance des propriétés physico-chimiques des solutions de polymères utilisées en récupération assistée des hydrocarbures (RAH) est essentielle pour une bonne efficience du procédé. Ces travaux avaient pour but de conforter et enrichir un modèle de viscosité universelle dépendant du paramètre de recouvrement C[η] qui permet de prendre en compte l'occupation du milieu par les chaînes macromoléculaires (concentration d'enchevêtrement critique, C*, régimes dilué et semi-dilué). Les effets des microstructures, de la taille et de la composition des polymères ont été étudiés via la synthèse d'une librairie d'échantillons par polymérisation radicalaire contrôlée (RADT/MADIX) : polyacrylamides, copolymères statistiques et asymétriques acrylamide-acrylate de sodium, polyacrylamides post-hydrolysés. Chaque polymère a été caractérisé par chromatographie d'exclusion stérique et par rhéologie capillaire dont les protocoles et techniques ont été optimisées. Les effets de la microstructure sur les propriétés physico-chimiques dimensionnelles, rhéologiques et complexantes ont été déterminés. Mes travaux de thèse doivent répondre aux deux questions principales suivantes : Quel est l'effet de la microstructure et de la dispersité du polymère sur le modèle ? Quelle(s) est (sont) la(les) limite(s) du modèle en termes d'application ? Mes travaux incluent donc l'élaboration de polymères modèles couvrant une large gamme de masses molaires (de quelques dizaines de milliers à plusieurs millions de g/mol). Les polymères modèles sont de structures variées allant d'homopolymères aux copolymères statistiques et à blocs. Après leur caractérisation complète (composition chimique et structure), les propriétés rhéologiques des solutions sont étudiées. Pour cela, mes travaux comprennent le développement, au sein du laboratoire et spécifiquement pour cette étude, d'un rhéomètre capillaire. Les résultats expérimentaux sont alors comparés au modèle établi pour les polymères industriels pour accroître le potentiel du modèleThe knowledge of the physico-chemical properties of polymer solutions for enhanced oil recovery (EOR) is crucial to optimize the process. The purpose of this work was to consolidate and complete an universal viscosity model depending on C[η] parameter. The later allows taking into account the degree of interpenetration of polymer chains (critical concentration, C*, diluted and semi-diluted solutions). Various polymer parameters have been studied as the effects of microstructures, polymer size (molar mass and dispersity) as well as chemical composition. A library of polymer models was elaborated by controlled radical polymerization (RADT/MADIX). Series of polyacrylamides, statistical and asymmetric copolymers of acrylamide-sodium acrylate and post-hydrolyzed polyacrylamides were synthesized and characterized by steric exclusion chromatography and capillary rheology and the analytical protocols and techniques were optimized. The effects of the microstructure onto dimensional, rheological and complexation physico-chemical properties were determined
3
Wang, Aileen Ruiling Zhu Shiping. "Diffusion-controlled atom transfer radical polymerization". *McMaster only, 2005.
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Mochizuki, Shuto. "Controlled radical polymerization in designed porous materials". Kyoto University, 2019. http://hdl.handle.net/2433/242535.
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5
Qi, Genggeng. "Unconventional radical miniemulsion polymerization". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26547.
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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Jones, Christopher W.; Committee Chair: Schork, F. Joseph; Committee Member: Koros, William J.; Committee Member: Lyon, Andrew; Committee Member: Nenes, Athanasios. Part of the SMARTech Electronic Thesis and Dissertation Collection.
6
Yin, Meizhen. "Synthesis and controlled radical polymerization of multifunctional monomers". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2004. http://nbn-resolving.de/urn:nbn:de:swb:14-1091453146703-47835.
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Multifunctional monomers on the basis of acryl- and methacryl derivatives were synthesized and different protective groups were used. After polymerization the protective groups were removed by different methods. Various initiators for the NMP of the monomers were synthesized and the reaction conditions were optimized. The results showed that NMP was not a suitable method for multifunctional acryl- and methacryl derivatives to achieve well-defined homopolymers, although it was successful for control of polymerization of styrene and block copolymerization of multifunctional acryl- and methacryl derivatives with alkoxyamine terminated polystyrene. The ATRP of multifunctional acrylates and methacrylates has been successfully performed, as well as the block copolymerization of multifunctional acrylates and methacrylates. Relatively low polydispersities of the corresponding polymers (PD=1.18-1.36) and reasonably high rates of polymerization could be achieved when Me6TREN and PMDETA were used as ligands. However, the ATRP of multifunctional acrylamides and methacrylamides failed. The RAFT-polymerization of styrene, acrylamide and acrylate using BDTB as a CTA and AIBN as an initiator afforded polymers with narrow molecular weight distribution (PD=1.13-1.26). A kinetic investigation and the further synthesis of block copolymers using dithioester-terminated homopolymers as macroCTAs showed that the RAFT polymerization of acrylamide M9b proceeded in a living manner. However, BDTB does not control the reaction of methacrylic monomers, such as methacrylates and methacrylamides. The bulk phase behavior of the block copolymers were examined by means of DSC and the surface behaviors of block copolymers as thin layers were examined with AFM. Two-phase transitions in the block copolymers were observed clearly by DSC, indicative of the appearance of phase separations, which were seen in an AFM image. In conclusion, multifunctional acryl- and methacryl derivatives failed to achieve well-defined homopolymers by NMP. However, this method was successful for block copolymerization of multifunctional acryl- and methacryl derivatives with alkoxyamine terminated polystyrene. Multifunctional acrylates and methacrylates were successfully homopolymerized and block copolymerized by ATRP. Multifunctional acrylates and acrylamides were suitable for homopolymerization and block copolymerization by the RAFT process. Thus far, it is difficult to homopolymerize multifunctional methacrylamides in controlled way.
7
Heredia, Karina Lynn. "Synthesis of polymer bioconjugates using controlled radical polymerization". Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1583873071&sid=37&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Minaux, Eric. "Controlled radical polymerization at pressures up to 2000 bar". Doctoral thesis, [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=962677035.
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Carlmark, Anna. "Complex Macromolecular Architectures by Atom Transfer Radical Polymerization". Doctoral thesis, KTH, Fibre and Polymer Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3740.
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Controlled radical polymerization has proven to be a viableroute to obtain polymers with narrow polydispersities (PDI's)and controlled molecular weights under simple reactionconditions. It also offers control over the chain-]ends of thesynthesized polymer. Atom transfer radical polymerization(ATRP) is the most studied and utilized of these techniques. Inthis study ATRP has been utilized as a tool to obtain differentcomplex macromolecular structures.
In order to elaborate a system for which a multitude ofchains can polymerize in a controlled manner and in closeproximity to one another, a multifunctional initiator based onpoly(3-ethyl-3-(hydroxymethyl)oxetane was synthesized. Themacroinitiator was used to initiate ATRP of methyl acrylate(MA). The resulting dendritic-]linear copolymer hybrids hadcontrolled molecular weights and low PDI's. Essentially thesame system was used for the grafting of MA from a solidsubstrate, cellulose. A filter paper was used as cellulosesubstrate and the hydroxyl groups on the cellulose weremodified into bromo-]ester groups, known to initiate ATRP.Subsequent grafting of MA by ATRP on the cellulose made thesurface hydrophobic. The amount of polymer that was attached tothe cellulose could be tailored. In order to control that thesurface polymerization was -eliving-f and hence that thechain-]end functionality was intact, a second layer of ahydrophilic monomer, 2-hydroxyethyl methacrylate, was graftedonto the PMA- grafted cellulose. This dramatically changed thehydrophilicity of the cellulose.
Dendronized polymers of generation one, two and three weresynthesized by ATRP of acrylic macromonomers based on2,2-bis(hydroxymethyl)propionic acid. In the macromonomerroute, macromonomers of each generation were polymerized byATRP. The polymerizations resulted in polymers with low PDI's.The kinetics of the reactions were investigated, and thepolymerizations followed first-order kinetics when ethyl2-bromopropionate was used as the initiator. In the-egraft-]onto-f route dendrons were divergently attached to adendronized polymer of generation one, that had been obtainedby ATRP.
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Aksakal, Resat. "Functional polymers via Cu-mediated radical polymerization". Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/36215.
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This work reports the investigation of Cu-mediated polymerization systems and its limits, in order to obtain functional branched polymers, in particular star-shaped and graft-shaped polymers. A novel initiator structure has allowed developing a new approach to synthesise sequence controlled multiblock star polymers via Cu-mediated reversible deactivation radical polymerization (RDRP) in water. This technique allows the preparation of pentablock star shaped polymers in just under 90 minutes of reaction time. The obtained polymers had a good agreement between theoretical and experimental molecular weights and excellent control over molecular weight distribution. Alternatively, the Cu-mediated RDRP of star polymers using a British 1 penny coin was described, displaying similar results as in the literature, providing better experimental conditions. As the copper coin was recovered unharmed, the catalyst was found to be economically very effective. Furthermore, poly(2-ethyl oxazoline) (PEtOx) was polymerized with good control and partially hydrolysed to poly(ethylene imine) (PEI) to yield PEtOx-r-PEI using a microwave reactor. The secondary amines of PEI was converted to macroinitiators, to allow the polymerization of acrylamides in aqueous medium, resulting in graft type polymers based on a poly(oxazoline) backbone with acrylamide side chains. Finally, the synthesis of carbohydrate-monomers was described, which allows to obtain monomers with a different number of carbohydrates (one, two or three). These monomers were polymerised via aqueous SET-LRP, to explore their interaction with carbohydrate binding lectins and to understand the impact on binding of carbohydrate density on polymers and polymer chain length.
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Özyürek, Zeynep. "Thermoresponsive Glycopolymers via Controlled Radical Polymerization (RAFT) for Biomolecular Recognition". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1190291104620-73670.
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Stimuli responsive polymers (SRP) have attracted a lot of attention, due to their potential and promising applications in many fields, as protein-ligand recognition, on-off switches for modulated drug delivery or artificial organs. Poly(N-isopropylacrylamide) (PNIPAM) is one of the most widely studied polymers due to its lower critical solution temperature (LCST) at ~ 32° C in aqueous solution. Additionally, glycopolymers, where free sugar units are present, have potentially interesting applications especially in bio-recognition where sugars play an important role. In this work, our interest was focused on the synthesis of glycomonomers and its block- and random- copolymers with NIPAM. NIPAM homopolymers with an active chain transfer unit at the chain end could be prepared by RAFT. They were used as macro-chain transfer agents to prepare a variety of sugar containing responsive block copolymers from new glycomonomers by the monomer addition concept. The LCSTs of the aqueous solutions of the copolymers are affected strongly by the comonomer content, spacer chain length of the glycomonomer and the chain architecture of the copolymers. These polymers were coated on a solid substrate by spin coating and crosslinked by plasma immobilization. Characterization of the polymers was performed by nuclear magnetic resonance spectroscopy (NMR), ultraviolet (UV), dynamic light scattering (DLS, detection of aggregation behaviour) and gel permeation chromatography (GPC). Polymer films were investigated by ellipsometry, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) regarding their surface properties. Afterwards sulfation of sugar – OH groups was performed in order to obtain heparin like structure, as heparin exhibits numerous important biological activities, like good interaction with diverse proteins. Finally, affinity of the polymers (sulfated and non sulfated form) on a solid support to the endothelial cells was investigated.
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Yu, Bonan. "Optimization of Benzocyclobutene Containing Methacryalte Structure for Controlled Radical Polymerization". University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1398938075.
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Aran, Bengi. "Polymerization And Characterization Of Methylmethacrylate By Atom Transfer Radical Polymerization". Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605042/index.pdf.
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In this work, methylmethacrylate, MMA was polymerized by ATRP method to obtain low molecular weight living polymers. The initiator was p-toluenesulfonylchloride and catalyst ligand complex system were CuCl-4,4&rsquodimethyl 2,2&rsquo
bipyridine. Polymers with controlled molecular weight were obtained. The polymer chains were shown by NMR investigation to be mostly syndiotactic. The molecular weight and molecular weight distribution of some polymer samples were measured by GPC method. The K and a constants in [h]=K Ma equation were measured as 9.13x10-5 and 0.74, respectively. FT-IR and X-Ray results showed regularity in polymer chains. The molecular weight-Tg relations were verified from results of molecular weight-DSC results.
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Russum, James. "Controlled Radical Polymerizations in Miniemulsions: Advances in the Use of RAFT". Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-10112005-105314/.
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Thesis (Ph. D.)--Chemical and Biomolecular Engineering, Georgia Institute of Technology, 2006.Jones, Christopher, Committee Chair ; Schork, F. Joseph, Committee Co-Chair ; Weck, Marcus, Committee Member ; Meredith, Carson, Committee Member ; Agrawal, Pradeep, Committee Member.
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Ejaz, Muhammad. "Controlled Surface Grafting of Well-Defined Polymers by Living Radical Polymerization Techniques". 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/150698.
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De, Camargo Chaparro Thaissa. "Synthesis of nanocomposites with anisotropic properties by controlled radical emulsion polymerization Lorena". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1045/document.
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L'objectif de ce travail de thèse est de préparer des latex nanocomposites à base d’argile, la Laponite RD, en émulsion aqueuse, à l'aide de la polymérisation radicalaire contrôlée par transfert de chaîne réversible par addition-fragmentation (RAFT). Les plaquettes de Laponite ont été choisies comme charge inorganique surtout pour leur anisotropie de forme, ce qui pourrait permettre l’elaboration de films nanostructurés, mais aussi pour leurs propriétés thermiques et mécaniques, leur pureté chimique élevée et la distribution uniforme en taille des plaquettes. Des polymères hydrophiles (macroRAFT) à base de polyéthylène glycol (PEG), d’acide acrylique (AA) ou de méthacrylate de N,N- diméthylaminoéthyle (DMAEMA) et comportant des unités hydrophobes d’acrylate de n-butyle (ABu) (dans certains cas) et un groupe trithiocarbonate terminal, ont été tout d'abord synthétisés. Ensuite, l'interaction entre les macroRAFTs et l’argile a été étudiée à travers le tracé des isothermes d'adsorption. En agissant comme des agents de couplage et des stabilisants, ces macroRAFTs ont eté utilisés dans la copolymérisation en émulsion du (méth)acrylate de méthyle et de l’ABu en mode semi-continu en presence d’argile. Des particules de latex hybrides de différentes morphologies ont été obtenues et les morphologies ont été reliées à la nature et à la concentration de l’agent macroRAFT, au pH de la dispersion macroRAFT/Laponite, à la température de transition vitreuse du copolymère final (fonction de la composition du mélange de monomères hydrophobes) et aux conditions de polymérisation. Les analyses par cryo-MET indiquent des plaquettes de Laponite décorées par des particules de polymère (plusieurs particules de latex en surface des plaquettes d'argile), des particules ‘haltère’, janus, ‘carapace’ (particules de latex décorées en surface par les plaquettes de Laponite) ou encore des particules multi-encapsulées (plusieurs plaquettes encapsulées dans chaque particule de latex). Les propriétés mécaniques des films de polymère/Laponite ont été étudiées par spectrométrie mécanique dynamique et corrélées à la morphologie des particules et à la microstructure des filmsThe aim of this work is to prepare Laponite RD-based nanocomposite latexes by aqueous emulsion polymerization, using the reversible addition-fragmentation chain transfer (RAFT) polymerization. Laponite platelets were selected as the inorganic filler due, especially, to their anisotropic shape, which allows the production of nanostructured films, but also for their thermal and mechanical properties, their high chemical purity and the uniform dispersity of the platelets. Hydrophilic polymers (macroRAFT) composed of poly(ethylene glycol) (PEG), acrylic acid (AA) or N,N-dimethylaminoethyl methacrylate (DMAEMA) and comprising hydrophobic n-butyl acrylate (BA) units (in some cases) and trithiocarbonate terminal group were initially synthesized. Then, the interaction between the macroRAFTs and the clay was studied through the plot of adsorption isotherms. By acting as coupling agents and stabilizers, the macroRAFT agents were used in the emulsion copolymerization of methyl (meth)acrylate and BA by semi-continuous process in the presence of the clay. Hybrid latex particles with different morphologies were obtained and the results were associated to the nature and concentration of the RAFT (co)polymers, to the pH of the macroRAFT/Laponite dispersion, the glass transition temperature of the final copolymer (function of the composition of the hydrophobic monomers mixture) and to the polymerization conditions. The cryo-TEM images indicate the formation of polymerdecorated Laponite platelets (several latex particles located at the surface of the platelets), dumbbell-like, janus, Laponite-decorated (armored) latex particles, and multiple encapsulated particles (several platelets inside each latex particle). The mechanical properties of polymer/Laponite films were studied by dynamic mechanical analysis and correlated with the particles morphology and the films microstructure
Este trabalho de tese tem como objetivo a preparação de látices nanocompósitos à base da argila Laponita RD em emulsão aquosa, via polimerização radicalar controlada por transferência de cadeia via adição-fragmentação reversível (RAFT). A Laponita foi escolhida como carga inorgânica devido principalmente à forma anisotrópica de suas lamelas, o que permite a elaboração de filmes nanoestruturados, mas também por suas propriedades térmicas e mecânicas, por sua alta pureza química e pela distribuição uniforme, em termos de tamanho, de suas partículas. Inicialmente, polímeros hidrofílicos (macroRAFT) à base de poli(etileno glicol) (PEG), de ácido acrílico (AA) ou de metacrilato de N,N-dimetilaminoetila (DMAEMA) que contêm unidades hidrofóbicas de acrilato de nbutila (ABu) (em alguns casos) e um grupo tritiocarbonílico terminal foram sintetizados. Em seguida, a interação entre os macroagentes de controle (macroRAFTs) e a argila foi estudada através de isotermas de adsorção. Atuando como agentes de acoplamento e estabilizantes, esses macroRAFTs foram então utilizados na copolimerização em emulsão do (met)acrilato de metila e do ABu em processo semicontínuo na presença da argila Laponita. Partículas de látex híbrido de diferentes morfologias foram obtidas e os resultados foram correlacionados à natureza e à concentração dos macroRAFTs, ao pH da dispersão macroRAFT/Laponita, à temperatura de transição vítrea do copolímero final (função da composição da mistura de monômeros hidrofóbicos) e às condições de polimerização. As análises de cryo-TEM indicam a formação de lamelas de Laponita decoradas com partículas de polímero (várias partículas de látex localizadas na superfície das lamelas), de partículas do tipo dumbbell, janus, blindadas (partículas de látex decoradas com lamelas de argila em sua superfície) ou ainda de partículas multiencapsuladas (diversas lamelas encapsuladas dentro de uma única partícula de látex). As propriedades mecânicas dos filmes de polímero/Laponita foram estudadas por análise dinâmico-mecânica e correlacionadas à morfologia das partículas e à microestrutura dos filmes
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Higashimura, Hideyuki. "Radical-controlled oxidative polymerization of phenols : a new methodology for polymer synthesis". 京都大学 (Kyoto University), 2005. http://hdl.handle.net/2433/144858.
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Bortolamei, Nicola. "Electrochemistry for atom transfer radical polymerization: from mechanism to more controlled synthesis". Doctoral thesis, Università degli studi di Padova, 2012. http://hdl.handle.net/11577/3422094.
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Living/controlled radical polymerizations (L/CRPs) have been developed in the second half of the nineties and nowadays are among the most powerful and effective polymerization techniques for the preparation of advanced polymeric materials with well defined properties and high value.
Atom Transfer Radical Polymerization (ATRP) has recorded the highest success in the field of L/CRP, thanks to its versatility and easiness of application. The first goal of this Ph.D. thesis is to understand and develop Cu-catalyzed ATRP through an electrochemical approach, with particular regard to the properties of the catalysts, initiators and propagating radicals, and the rationalization of the activation mechanism. Besides these fundamental aspects, a second important goal is to open a new way to enhance the control of the polymeric synthesis and allow the catalyst regeneration by means of electrochemical tools.Le polimerizzazioni radicaliche controllate (Controlled radical polymerization, CRP) sono state sviluppate a partire dalla metà degli anni '90, e attualmente sono tra le più potenti ed efficaci metodologie di polimerizzazione per ottenere materiali polimerici avanzati con proprietà ben definite ed alto valore aggiunto. La polimerizzazione radicalica a trasferimento di atomo (Atom Transfer Radical Polymerization, ATRP) è la tecnica che ha riscontrato il maggior successo nel campo delle CRP grazie alla sua versatilità e facilità di applicazione. Scopo di questa tesi di dottorato è di fornire un contributo alla comprensione e allo sviluppo di ATRP catalizzata da rame attraverso un approccio elettrochimico, con particolare riguardo alle proprietà di: catalizzatore, specie dormiente e radicali propaganti, e alla comprensione del meccanismo di attivazione. Inoltre, un secondo importante obbiettivo è quello di sviluppare nuove metodologie elettrochimiche atte ad aumentare il controllo delle sintesi polimeriche e permettere la rigenerazione del catalizzatore.
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Çakir, Pinar. "Molecularly imprinted polymer nanostructures by controlled / living radical polymerization with multi-iniferters". Compiègne, 2012. http://www.theses.fr/2012COMP2018.
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Les polymères à empreintes moléculaires (MIPs) sont des matériaux synthétiques contenant des cavités capables de reconnaître spécifiquement une molécule cible. Ils se présentent comme une alternative intéressante face aux anticorps biologiques en raison de leur meilleure stabilité chimique et physique, leur meilleure disponibilité et leur moindre coût. Traditionnellement, les MIPs sont synthétisés par polymérisation de monolithes, qui sont ensuite broyés mécaniquement, engendrant des particules de taille micrométrique et de formes irrégulières. Durant ces dernières années, de nombreuses techniques de polymérisation ont été développées afin d’obtenir des particules MIP sphériques de tailles micro et nanométriques, et plus particulièrement des nanogels quasi-solubles. Dans l’optique d’une application en biologie, des tailles de quelques nanomètres - de l’ordre de grandeur de la taille des protéines – sont souhaitées, ce qui pose un réel défi pour leur synthèse, car la faible densité du matériau (une particule ne consiste que de quelques chaines de polymère) s'oppose à l'impression d'une mémoire moléculaire. Nous avons développé une nouvelle approche de synthèse de MIP nanogels dont la taille est proche de celle des anticorps naturels. Notre stratégie est basée sur l’utilisation d’un nouveau type d'amorceur pour la polymérisation radicalaire contrôlée comprenant des fonctions iniferter multiples attachées à un noyau dendritique. Cela permet de générer une concentration localement élevée de radicaux et ainsi, d'obtenir des nanogels de polymère dont la densité est augmentée. Ces travaux de thèse ont conduit à l’obtention des nanogels de MIP de 17 nm de diamètre avec un effet impression appréciable, une bonne affinité pour la cible, le beta-antagoniste propranolol, et une sélectivité moléculaire prononcée. En plus de la synthèse des nanogels solubles de MIP, des motifs de MIP micro et nanostructurés ont été greffés sur des surfaces planes de silicium. Le multiiniferter a été imprimé à la surface par lithographie douce, et fixé chimiquement par son groupement carboxyle central. Les MIPs ont ensuite été synthétisés par une approche « bottom up », caractérisés par spectroscopie d'émission optique, la spectroscopie Raman et la microscopie à force atomique, et la reconnaissance moléculaire de la cible a été visualisée par microscopie de fluorescence. Ces nouveaux matériaux, nanogels et surfaces imprimées offrent de nombreuses perspectives pour la détection par biocapteurs et biopuces, en particulier dans le domaine du biomédicalMolecularly imprinted polymers (MIPs) are synthetic materials with specific recognition properties for target molecules. They are considered an alternative to antibodies and are characterized by a higher chemical and physical stability, better availability and lower cost. Historically, MIPs were synthesized as bulk monoliths that were subsequently broken down mechanically in order to form particles of a size in the micrometer range, with irregular shapes. During the last decade, research has focused on the direct synthesis of spherical MIP micro and nanoparticles, and, more recently, on protein-sized, quasi-soluble MIP nanogels in order to widen the application range of MIPs in the biological field. The main difficulty of synthesizing MIPs with diameters in the low nm region is the low density of the resulting polymer network consisting only of a few polymer chains, which makes it difficult to imprint and maintain a molecular memory. In this thesis, we propose an original approach to the synthesis of quasisoluble MIP nanogels with a size in the low nm range, close to that of real antibodies. The proposed procedure involves a new type of initiator for controlled/living radical polymerization, based on multiple iniferter moieties attached to a dendritic core. This allows for the generation of a higher local radical density, and thus for the synthesis of denser nanogels. By using this strategy, MIP Nanogels of 17 nm size with an appreciable molecular imprinting effect, a good affinity for the target molecule, the chiral drug propranolol, and a good selectivity were obtained. In addition, these multiiniferters were also used for the bottom-up synthesis of thin MIP patterns on silicon wafers, by surface-initiated polymerization. The multi-iniferter was printed on to the surface by soft lithography and chemically attached through its carboxyl-functionalized core, followed by the in-situ synthesis of the MIP. Well defined MIP patterns were obtained, which were characterized by optical emission spectroscopy, Raman spectroscopy, atomic force microscopy, and the specific binding of the target molecule was visualized by fluorescence microscopy. We believe that the synthesis, in solution and at surfaces, of protein-size MIP nanogels with specific recognition properties will provide new opportunities for biosensors and biochips technologies in biomedical applications
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Vosloo, Johannes Jacobus. "Controlled free radical polymerization in miniemulsion using Reversible Addition-Fragmentation Chain Transfer (RAFT)". Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52174.
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Thesis (MSc)--Stellenbosch University, 2001.ENGLISH ABSTRACT: A novel approach to conducting controlled free radical polymerization in aqueous systems using Reversible Addition-Fragmentation Chain Transfer (RAFT) has been studied. When conducting RAFT in aqueous systems, reaction conditions must be chosen such that monomer transport across the aqueous-phase is either eliminated or facilitated. This is to prevent the formation of the red layer associated with RAFT in emulsions. The formation of the red layer is ascribed to the inability of waterinsoluble, dithiobenzoate-endcapped oligomers to be sufficiently transported across the aqueous phase. The novel approach in this study focussed on eliminating monomer transport and comprises two fundamental steps: the synthesis of dithiobenzoate-encapped oligomers in bulk followed by miniemulsification of these oligomers to yield a polymerizable miniemulsion. Dithioesters that act as chain transfer agents in the RAFT -process were synthesized in situ, thereby eliminating laborious and time-consuming organic purification procedures of dithioesters. In situ formation of the RAFT-agents involved conducting the reaction between di(thiobenzoyl) disulfide and conventional azo-initiators of differing structures in the presence of monomer. The structure of the chosen azo-initiator played a role in the efficiency of the RAFT process when the reaction was conducted in the presence of monomer to control the free radical polymerization process. Synthesis of the oligomers was performed by heating di(thiobenzoyl) disulfide and a selected azo-initiator, in the presence of monomer for a specific reaction duration in bulk. After the reaction was stopped, these oligomers were then miniemulsified by adding water, surfactant and cosurfactant, followed by the application of shear to form the resulting mini emulsion. The free radical polymerization of the dithiobenzoate-endcapped oligomers in the miniemulsion proceeded in a controlled manner with molecular weight increasing in a linear fashion with increasing conversion, while polydispersities remained low. The familiar red layer formation associated with RAFT polymerization in conventional emulsions was not observed under these conditions. The effects of changing the cosurfactant (hydrophobe) as well as changing the degree of polymerization of the emulsified oligomers were also investigated and described.
AFRIKAANSE OPSOMMING: Hierdie studie is geloods om 'n nuwe benadering tot die beheerde vry-radikaal polimerisasie in water gebaseerde sisteme te ondersoek. Daar is spesifiek gekyk na die uitvoer van die RAFT (Reversible Addition-Fragmentation Chain Transfer) proses in emulsies. Wanneer RAFT in emulsies toegepas word, moet die toestande waaronder die reaksie uitgevoer word, versigtig opgestel word. Die toestande moet so gekies word dat die vervoer van monomere deur die waterfase óf geëlimineer word óf gefasiliteer word. Dit word gedoen om die faseskeiding in die vorm van 'n rooi laag, wat so kenmerkend van RAFT -polimerisasie in emulsies is, te voorkom. Hierdie faseskeiding vind plaas omdat die vervoer van ditiobensoaat endgroep-bevattende oligomere deur die waterfase tydens interval II, moeilik is a.g.v. hulle oplosbaarheid in water. Die nuwe benadering wat hier bestudeer is, het twee basiese stappe. Eerstens word die ditiobensoaat endgroep-bevattende oligomere in bulk gesintetiseer. Dit word gevolg deur die emulsifisering van die oligomere. Hierna vind verdere polimerisasie van die oligomere plaas deur die dormante oligomere te heraktiveer. Die ditio-esters wat as kettingoordrag agente optree in die RAFT proses, word in situ gesintetiseer. Hierdie modifikasie sny tydrowende organiese suiweringsmetodes uit. Die in situ RAFT agente word gesintetiseer deur di(tiobensoïel) disulfied met verskillende konvensionele azo-inisieerders te laat reageer. Die struktuur van die spesifieke azoinisieerder het wel 'n rol gespeel in die effektiwiteit van die RAFT proses om molekulêre massa te beheer as bg. reaksie in die teenwoordigheid van monomere uitgevoer is. Die sintese van die oligomere is gedoen deur di(tiobensoïel) en 'n azo-inisieerder te verhit in die teenwoordigheid van monomere. Die reaksie is gedoen in bulk en die graad van polimerisasie van die oligomere is beheer deur die reaksie te stop by verskillende tydstippe. Nadat die bulk reaksie gestop is, is hierdie oligomere ge-emulsifiseer deur die oligomere te meng met 'n seep, hidrofoob en water. Hierdie mengsel word dan onderwerp aan 'n vermengingskrag om 'n polimeriseerbare mini-emulsie te vorm. Die voortsetting van die polimerisasie van die oligomere in die mini-emulsie het op 'n beheerde wyse verloop, m.a.w. molekulêre massa wat linieêr toeneem met stygende omsetting. Polidispersiteit indekse van die polimere het deurentyd laag gebly in die stabielste sisteme. Onder hierdie toestande was daar geen kenmerkende rooi laagvorming te bespeur nie. Die effekte wat die verandering van die hidrofoob, asook die verandering van die graad van polimerisasie van die oligomere op die sisteem gehad het, is onder andere ook ondersoek en beskryf.
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Gonzato, Carlo. "Chemical nanosensors based on molecularly imprinted polymer nanocomposites synthesized by controlled radical polymerization". Compiègne, 2012. http://www.theses.fr/2012COMP2035.
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Les polymères à empreintes moléculaires (MIP, pour molecularly imprinted polymers en anglais) sont des récepteurs synthétiques, parfois appelés "anticorps en plastique", capables de reconnaitre et fixer spécifiquement une molécule cible. L’impression moléculaire s’est imposée, durant les trente dernières années, comme une technique pour la synthèse des structures réticulées possédant une remarquable affinité et sélectivité vis-à-vis d’une espèce chimique utilisée comme molécule empreinte dans un procédé de moulage au niveau moléculaire. La grande variété de matériaux et de formats accessibles à cette technique lui ont permis de trouver un grand nombre d’applications, telles que la séparation, les capteurs, la catalyse, le ré-largage contrôlé de médicaments. Depuis leur apparition, la plupart des MIPs a été synthétisée par polymérisation radicalaire libre (FRP) des monomères vinyliques. Cette méthode de polymérisation représente un excellent choix en termes de simplicité de mise en place, tolérance par rapport aux solvants et aux différents groupements fonctionnels des ingrédients. Cependant, plusieurs désavantages liés à cette technique limitent la possibilité d’obtenir un contrôle adéquate vis-à-vis de certaines caractéristiques fondamentales pour des applications en nano-technologies. L’introduction des techniques de polymérisation radicalaire contrôlée/vivante (CRP) a donc représentée une avancée importante et a permis de dépasser certains limites associés aux MIPs synthétisés par FRP. Dans ce contexte, ce travail de thèse a étudié les avantages provenant de l’utilisation d'une méthode CRP, le RAFT, pour la synthèse des MIP. Ce travail a été mené en se focalisant sur les caractéristiques principales des CRPs : le caractère vivant et, en même temps, contrôlé. Dans un premier temps, nous avons utilisé l’aspect vivant de la polymérisation pour la synthèse des nanocomposites MIP, possédant des propriétés superparamagnétiques. Celle-ci a été effectuée par polymérisation de couches p(EGDMA-co-MAA) par RAFT amorcée à la surface des particules de Fe3O4 préfonctionnalisées avec des groupements amine. Le greffage de ces couches a été obtenu en employant des ultrasons comme source d'agitation, et en testant différents solvants pour en apprécier l’influence sur la structure et la morphologie des composites résultants. Nous avons démontré que le greffage se produit d’une façon homogène, et que grâce au caractère vivant de la polymérisation RAFT, les composites peuvent être fonctionnalisés davantage, par exemple par des chaines p(EGMP), pour ajuster leur propriétés de surface. Dans un deuxième temps, nous nous sommes consacrés à une étude comparative visant la mise en évidence des avantages de la RAFT par rapport à la FRP en termes de performances des MIP acryliques et méthacryliques. Pour mieux apprécier les différences induites par la méthode de polymérisation, le dégrée de réticulation et donc la flexibilité des réseaux ont été variés de façon systématique. Cette stratégie a permis de bien apprécier les différences induites par chaque technique de polymérisation. Les résultats ont démontré que la RAFT permet de synthétiser des MIPs ayant une meilleure affinité pour leur molécule cible, et que cette amélioration est due à une distribution plus homogène des points de réticulation au sein du réseau. Finalement, nous avons appliqué la RAFT pour la synthèse de nanocapteurs individuels basés sur des composite MIP intégrant des nanoparticules d'or, et utilisant la spectroscopie Raman exaltée (SERS) pour la détectionMolecularly imprinted polymers (MIPs) are synthetic receptors, also known as antibody mimics, that can specifically bind target molecules. Molecular imprinting has emerged, over the last 30 years; it is an extremely versatile strategy for synthesizing networks possessing high affinity and selectivity for a chemical species, used as a molecular template during their synthesis. The wide variety of materials and formats that are accessible through this strategy has resulted in a broad spectrum of applications for such MIPs, ranging from separation to sensing, catalysis, drug delivery, etc. Since the beginning, the great majority of the imprinted networks has been synthesized by assembling vinyl monomers via free-radical polymerization (FRP). This polymerization method represents a convenient choice for synthesizing MIPs, due to its easy setup, versatility, tolerance with respect to many solvents and functional groups. However, some drawbacks greatly affect the possibility of achieving of suitable degree of control over some “polymeric” parameters which become important for specific applications. The introduction of controlled/”living” radical polymerization (CRP) techniques has then represented an opportunity for MIPs to reduce, and in some cases even to overcome, some of their limits arising from FRP. In this respect, this Ph. D. Thesis has studied how the use of RAFT polymerization, one of the most applied CRPs, can be advantageously used to syntheze MIPs. This has been done by focusing on the main characteristics of CRPs: their living and controlled nature. The living nature has been exploited during the first part of this work, which involved the synthesis of superparamagnetic molecularly imprinted nanocomposites via surface-initiated RAFT polymerization of p(EGDMA-co-MAA) on amino-modified Fe3O4 nanoparticles. The polymer grafting has been performed using an unusual stirring technique (i. E. Ultrasonication) during the polymerization step, and by testing different polymerization solvents for evaluating their effect on the composite structure. It has been observed that the grafting resulted in homogeneous polymer layers, the thickness of which could be controlled by adjusting the RAFT/radical source ratio. Moreover, the living nature of RAFT fragments has been exploited for post-functionalizing the surface of a composite particle with p(EGMP) brushes, thus demonstrating the potential of fine-tuning the particle surface properties through the living chain ends. In the second part of the thesis, an in-depth study has been performed on the effects induced by the use of controlled (RAFT) polymerization conditions on the binding behaviour and structural parameters of bulk acrylic and methacrylic MIPs and the corresponding non-imprinted polymers, synthesized by RAFT and FRP with varying cross-linking degree. This strategy actually provided scaffolds with progressively increased degree of flexibility (especially in the case of acrylics) which allowed visualize the enhancement of binding and structural differences arising from the polymerization technique. As a result, it has been observed that the use of controlled (RAFT) conditions induced, on the imprinted networks, an increased template affinity over equivalent FRPs, and it has been demonstrated that this improved affinity can be related to more homogeneous distributions of the cross-linking points achieved during RAFT polymerization. The third part presents preliminary results toward the synthesis by RAFT of individual multi-composite MIP nanosensors using enhanced Raman spectroscopy (SERS) for detection
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Ono, Isamu. "Optimization of the Structure of Benzocyclobutene Containing Methacrylate Monomer for Controlled Radical Polymerization". University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1468500945.
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Morin, Aurélie. "Controlled radical polymerization of vinyl esters and vinyl amides : experimental and theoretical studies". Thesis, Toulouse, INPT, 2013. http://www.theses.fr/2013INPT0117/document.
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Ces travaux de thèse portent sur la polymérisation radicalaire contrôlée (PRC) des esters et amides de vinyle. L’une des possibilités de contrôle est le piégeage dynamique réversible des chaînes radicalaires croissantes (P•) par un agent de contrôle (T) formant une espèce dormante (P─T’). La concentration en radicaux dans le milieu peut alors diminuer dramatiquement de sorte que les réactions indésirables de terminaisons soient négligeables et que le contrôle de la masse molaire des polymères soit atteint avec un faible indice de dispersité. L’utilisation de complexes métalliques, pouvant s’oxider et former une liaison métal-carbone, comme agent de piégeage des radicaux est une manière de réaliser ce contrôle. La PRC est alors appelée Polymérisation Radicalaire Contrôlée par voie Organométallique (OMRP). A ce jour, plusieurs métaux de transitions ont été utilisés avec plus ou moins de succès en OMRP. Lors de cette étude, nous avons synthétisé des complexes de cuivre(I) et testé leurs performances pour l’OMRP de l’acétate de vinyle et de l’éthylène. Nous avons également utilisé des outils de chimie théorique pour mieux comprendre pourquoi le cobalt(II) acétylacétonate est, jusqu’à aujourd’hui, le meilleur agent de contrôle pour la polymérisation de l’acétate de vinyle et des amides de vinyle. Grâce à la théorie de la fonctionnelle de densité (DFT), nous avons mis en lumière le rôle crucial de la coordination sur le cobalt des groupements carbonyles des monomères étudiésThis thesis focus on Controlled Radical Polymerization (CRP) of vinyl esters and vinyl amides. One of the possibilities to achieve this control is a dynamic reversible trapping of the growing radical chains (P•) by a controlling agent (T) to form a dormant species (P─T’). The radical concentration in the medium can be dramatically reduced so that the unwanted terminations are disfavored and polymers with controlled molecular weights and low dispersity can be obtained. A way to achieve this control is the use of metallic complexes, which can oxidize and form a metal-carbon bond, as trapping agent in the so-called Organometallic Mediated Radical Polymerization (OMRP). So far, different transition metals have been used with gretaer or smaller success. In this study, the synthesis of copper(I) complexes and their investigation for the vinyl acetate and ethylene polymerization under OMRP conditions were performed. We also used computational chemistry as a tool to better understand why the cobalt(II) acetylacetonate (Co(acac)2) has, so far, given the best results for either vinyl acetate or vinyl amides polymerization. Thanks to Density Functional Theory (DFT), the crucial role of the monomer carbonyl group coordination to cobalt was pointed out
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Park, Sangwoo. "Electrochemically Controlled Atom Transfer Radical Polymerization and Synthesis of Polymers with Complex Architectures". Research Showcase @ CMU, 2016. http://repository.cmu.edu/dissertations/1031.
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Atom transfer radical polymerization (ATRP) is one of the most broadly applied reversible deactivation radical polymerization (RDRP) technique that provide well-defined polymers with predetermined molecular weight (MW) and narrow molecular weight distribution (MWD). The functional polymers synthesized by ATRP showed a potential promise in the fields of biomedical applications such as smart drug delivery, tissue engineering, and diagnostic sensors. In general, conventional ATRP requires a large amount of transition metal catalysts (> 1000 parts per million (ppm) versus molar ratio of monomers) and removal of the residual catalysts is necessary for use of advanced materials in bio-applications. The advent of catalysts (re)generation from the oxidized transition metal/ligand catalysts allows for the use of ppm level of catalysts in an ATRP, and offers more environmentally benign and industrially favorable reaction conditions for the synthesis of polymers. This work mainly explores electrochemically controlled atom transfer radical polymerization (eATRP) with diminished catalysts conditions as one of many catalysts regeneration ATRP systems being examined in the past decade. This dissertation is composed of nine chapters. Chapter I reviews recent progress in electrochemically controlled chemical reaction and polymerization. Chapter II provides an in-depth study of eATRP and serves as a basis for the discussions in Chapter III on developing a simplified eATRP reaction (seATRP). Chapters II and III cover six appendices, which include related collaborations, explanations on catalysts development and characterization, polymerization mechanism, and evaluation of new polymerization procedures. Chapter IV and V address related aqueous eATRP techniques. Chapter IV details optimization of polymerization conditions for acrylamides and minimization of side reactions. Chapter V explores miniemulsion polymerization of n-butyl acrylate which requires optimization of aqueous-organic phase catalyst communication. Chapter VI addresses development of electrochemically mediated reversible addition-fragmentation chain transfer (eRAFT) polymerization of methyl methacrylate. Chapters VII to IX discuss the synthesis of copolymers with complex polymeric architectures, i.e., star polymers. Specifically in Chapter VII procedures for achieving high yield for the synthesis of stars by combining arm-first methods and eATRP to reduce initial intermolecular termination reactions. Chapter VII also contains an appendix on star synthesis by the core-first method via eATRP. Chapter VIII and IX elucidate applications of the functional star polymers. In Chapter VIII, the preparation and application of light induced crosslinkable star polymers in surface patterning are discussed and extended to biomedical applications. Lastly, Chapter IX encompasses temperature responsive surfaces, that were prepared by star polymers upon UV irradiation, as smart cell cultivate substrates.
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Bompart, Marc. "Molecularly imprinted polymers and nano-composites by free radical and controlled/living radical polymerization : applications in optical sensors". Compiègne, 2010. http://www.theses.fr/2010COMP1870.
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Cette thèse est organisée en trois chapitres basés sur trois publications et deux manuscrits en cours de soumission. Les polymères à empreintes moléculaires (MIP) sont des récepteurs produits à façon qui sont obtenues par polymérisation en présence de molécules modèles. Le premier papier décrit l'utilisation de la spectroscopie Raman pour la détection et la quantification de molécules modèles au sein d'une particule unique de polymères a empreintes moléculaires de taille micrométrique. Les particules de polymères ont eté imprimées avec comme molécules modèles S-propranolol. Des particules de taille nanométrique et micrométrique ont été respectivement utilisées pour une analyse en masse et sur particule unique. La quantification de molécules cibles est possible sur particule unique et une limite de détection de 1µM a été obtenue sur l’analyse en masse. Le second papier décrit un capteur chimique de taille nanométrique composé d’une particule en core-shell composite. Cette particule comprend un cœur polymérique, une enveloppe inorganique composée de nanoparticules d’or pour l’exaltation du signal, recouvert d’une couche de polymères à empreintes moléculaires pour la reconnaissance. La méthode d’analyse utilisée est une exaltation su signal Raman appelé « surface enchanced Rama scattering ». Ces particules ont aussi été utilisées comme capteur avec la résonance plasmonique localisé comme méthode de transduction (papier n°3). Afin de résoudre certains problèmes associés aux polymères à empreintes moléculaires, tels que l’inhomogénéité en terme de morphologie et de distribution en site de reconnaissance, il a été suggéré d’utiliser des méthodes de polymérisations radicalaire contrôlées. Ces méthodes facilitent aussi leurs synthèses sous forme de nanomatériaux, nanocomposites et films minces. Le quatrième papier considère les récents avantages et inconvénients de ces nouvelles méthodes de polymérisation rapportés aux polymères à empreintes moléculaires. Le dernier papier décrit la première utilisation d’un récente méthode basée sur la polymérisation par transfert à l’iode (ITP), « reversible chain transfer catalyzed polymerization » (RTCP) adapté aux polymères à empreintes moléculaires. Nous décrivons un exemple de synthèse de MIP spécifiques pour la molécule propanolol par RTCP, produisant des polymères sous forme de « bulk » ou particules ayant la même capacité de reconnaissance que ceux synthétisés par polymérisation radicalaire (FRP). La RMN à l’état solide a révélée que la conversion en double liaison intramoléculaire était plus élevée dans le cas de polymères synthétisés par RTCP que par FRP, en particulier à haute concentration en amorceurThis thesis is organized in three chapters and is based on three published papers, and two manuscripts about to be submitted. Molecularly imprinted polymers (MIPs) are tailor-made synthetic receptors that are obtained by polymerization in the presence of a molecular template. The first paper describes the use of Raman spectroscopy to detect and quantify the presence of the imprinting template in single molecularly imprinted polymer microspheres. The polymers were imprinted with the Beta-blocking drugs propranolol and atenolol, and precipitation polymerization was used to obtain spherical particles. The nanoparticles were used for bulk detection whereas with micrometer-sized particles, quantitative measurements on single particles were possible. Relatively low detection limits down to 1µM have been reached for the detection of S-propranolol through bulk measurements on MIP nanoparticles. The second paper describes chemical nanosensors with a submicron core-shell composite design, based on a polymer core, a molecularly imprinted polymer (MIP) shell for selective analyte recognition, and an interlayer of gold nanoparticles for signal amplification. SERS measurements on single nanosensors yielded a detection limit of 10-7 M for the Beta-blocker propranolol, several orders of magnitude lower than on plain MIP spheres. These particles were also used as sensor materials with localized surface plasmon resonance measurements as the transduction method (Paper III), for the determination of the Beta-blocking drug propranolol. The sensors were used in suspension and were measured using a standard UV-Vis spectrophotometer. In order to solve general problems associated with MIPs, in particular their heterogeneity in terms of inner morphology and distribution of binding site affinities, it has been suggested to use modern methods of controlled/living radical polymerization for their synthesis. This also facilitates their generation in the form of nanomaterials, nanocomposites, and thin films, a strong recent trend in the field. The fourth paper reviews recent advances in the molecular imprinting area, with special emphasis on the use of controlled polymerization methods, their benefits, and current limitations. In the last paper, we have for the first time used a recently developed CRP method based on iodide mediated polymerization, reversible chain transfer catalyzed polymerization (RTCP), for the synthesis of MIPs. We show on the example of MIPs specific for the Beta-blocking drug propranolol that RTCP is compatible with MIP synthesis, both for the synthesis of bulk polymers and nanospheres, and that it yields polymers with the same binding capacity as the standard FRP method used for comparison. Solid-state NMR measurements revealed that the conversion of pendant vinyl groups was higher with RTCP than with polymers synthesized by FRP, in particular at higher initiator concentrations
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Bergenudd, Helena. "Understanding the mechanisms behind atom transfer radical polymerization : exploring the limit of control". Doctoral thesis, KTH, Kärnkemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-32104.
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Atom transfer radical polymerization (ATRP) is one of the most commonly employed techniques for controlled radical polymerization. ATRP has great potential for the development of new materials due to the ability to control molecular weight and polymer architecture. To fully utilize the potential of ATRP as polymerization technique, the mechanism and the dynamics of the ATRP equilibrium must be well understood. In this thesis, various aspects of the ATRP process are explored through both laboratory experiments and computer modeling. Solvent effects, the limit of control and the use of iron as the mediator have been investigated. It was shown for copper mediated ATRP that the redox properties of the mediator and the polymerization properties were significantly affected by the solvent. As expected, the apparent rate constant (kpapp) increased with increasing activity of the mediator, but an upper limit was reached, where after kpapp was practically independent of the mediator potential. The degree of control deteriorated as the limit was approached. In the simulations, which were based on the thermodynamic properties of the ATRP equilibrium, the same trend of increasing kpapp with increasing mediator activity was seen and a maximum was also reached. The simulation results could be used to describe the limit of control. The maximum equilibrium constant for controlled ATRP was correlated to the propagation rate constant, which enables the design of controlled ATRP systems. Using iron compounds instead of copper compounds as mediators in ATRP is attractive from environmental aspects. Two systems with iron were investigated. Firstly, iron/EDTA was investigated as mediator as its redox properties are within a suitable range for controlled ATRP. The polymerization of styrene was heterogeneous, where the rate limiting step is the adsorption of the dormant species to the mediator surface. The polymerizations were not controlled and it is possible that they had some cationic character. In the second iron system, the intention was to investigate how different ligands affect the properties of an ATRP system with iron. Due to competitive coordination of the solvent, DMF, the redox and polymerization properties were not significantly affected by the ligands. The differences between normal and reverse ATRP of MMA, such as the degree of control, were the result of different FeIII speciation in the two systems.QC 20110406
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Jordan, Rainer, Tao Zhang, Yunhao Du, Felix Müller e Ihsan Amin. "Surface-initiated Cu(0) mediated controlled radical polymerization (SI-CuCRP) using a copper plate". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-188989.
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Surface engineering with polymer brushes has become one of the most versatile techniques to tailor surface properties of substrates for a broad variety of (bio-) technological applications. We report on a new facile approach to prepare defined and dense polymer brushes on planar substrates by surface-initiated Cu(0) mediated controlled radical polymerization (SI-CuCRP) of numerous vinyl monomers using a copper plate at room temperature. The fabrication of a variety of homo-, block, gradient and patterned polymer brushes as well as polymer brush arrays is demonstrated. The SI-CuCRP was found to be strictly surface-confined, of highly living character, proceeds remarkably fast and results in polymer brushes of very high grafting densities. The brush layer thickness can be modulated by the polymerization time or by the distance of the copper plate to the modified substrate. As the copper plate can be reused multiple times, no additional copper salts are added and only minimal amount of chemicals is needed, the simple and low-cost experimental conditions allows researchers from various fields to prepare tailored polymer brush surfaces for their needs.
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Qiao, Xiaoguang. "Synthesis of silica-polymer hybrid particles via controlled radical polymerization in aqueous dispersed media". Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10332/document.
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Des polymères à base de méthacrylate de poly(oxyde d'éthylène) (PEOMA) avec des chaînes pendantes PEO (Mn = 300 ou 950 g mol-1) ou des copolymères de PEOMA300 et d'acide méthacrylique (AMA) ont été synthétisés par polymérisation radicalaire contrôlée par les nitroxydes en utilisant une alkoxyamine (BlocBuilder®) comme amorceur en présence de SG1 et d'une faible quantité de styrène. Les copolymères à base de PEOMA300 et d'AMA sont thermo- et pH-sensibles. Les deux types de macroalkoxyamines ont été utilisés pour amorcer la copolymérisation en émulsion du méthacrylate de n-butyle et du styrène et former, par auto-assemblage induit par la polymérisation, des particules composées de copolymères à blocs amphiphiles, en absence ou présence de particules de silice. En absence de silice, des particules stabilisées de façon stérique ou électrostérique ont été formées. La polymérisation présente les caractéristiques d'une polymérisation contrôlée avec néanmoins la formation d'une faible proportion de chaînes mortes. L'effet du pH, de la force ionique et de la nature ou de la concentration des macroalkoxyamines sur la cinétique de polymérisation et la morphologie des particules a été étudié, et des sphères, des vésicules ou des nanofibres ont été obtenues. Les macroalkoxyamines à base de PEO s'adsorbent sur la silice via la formation de liaisons hydrogène entre les chaînes PEO et les groupes silanol. La synthèse de copolymères à blocs en surface de la silice a conduit à la formation de particules hybrides de différentes morphologies (bonhomme de neige, multipodes, framboise, coeur-écorce, têtard, mille pattes) liées à la taille de la silice, au pH et à la nature du macroamorceurWater-soluble brush-type polymers composed of poly(ethylene)oxide methacrylate (PEOMA) units with PEO side groups of various chain lengths (Mn = 300 and 950 g mol-1) or of PEOMA300 with methacrylic acid (MAA) were synthesized by nitroxide-mediated polymerization using an alkoxyamine initiator (BlocBuilder®) and SG1 nitroxide in the presence of a low amount of styrene. The PEOMA300-MAA based copolymers showed a dual temperature/pH response. The two series of macroalkoxyamines were used in aqueous emulsion copolymerization of nbutyl methacrylate and styrene leading to the formation of particles composed of amphiphilic block copolymers through polymerization-induced self-assembly, in both the absence and presence of silica. The experiments performed in the absence of silica particles resulted in the formation of sterically or electrosterically stabilized latexes. The polymerization exhibited all the features of a controlled system with however the presence of a small proportion of dead chains. The effect of pH value, ionic strength and type and concentration of the macroalkoxyamine initiator on polymerization kinetics and latex morphologies was investigated. Depending on the reaction conditions, spherical particles, vesicles or nanofibers were successfully prepared. The PEO-based macroalkoxyamines were shown to adsorb on the silica surface via hydrogen bond interaction between PEO and the silanol groups. This enabled block copolymers to be generated in situ on the silica surface leading to hybrid particles with snowman, raspberry, daisy, core-shell, “tadpole-” and “centipede-” like morphologies depending on the silica particle size, pH value and type of macroinitiator
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Lang, Andreas [Verfasser], e Mukundan [Akademischer Betreuer] Thelakkat. "Semiconductor Polymer Architectures using Click Chemistry and Controlled Radical Polymerization / Andreas Lang. Betreuer: Mukundan Thelakkat". Bayreuth : Universitätsbibliothek Bayreuth, 2011. http://d-nb.info/101923458X/34.
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Lessard, Benoît. "Advances in Nitroxide-mediated controlled radical polymerization from Poly(Methacrylate)s to perfectly alternating copolymers". Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110396.
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Nitroxide mediated controlled radical polymerization (NMP) has been utilized since the early 1990s, as a simple and robust technique for the synthesis of various new polymeric architectures. Since the development of second generation initiators based on SG1 and TIPNO stable radicals, NMP is no longer restricted to the polymerization of just styrenics as it was initially and can now homopolymerize a plethoraof monomers such as acrylates and acrylamides. In this thesis, several advances in NMP due to these second generation initiators, were explored. The homopolymerization of methacrylates, by NMP, results inexcessive irreversible termination due to the elevated concentration of free radicals generated in the initial stages of the polymerization. However, the use of a small amount of a "controlling" comonomer can be used to control the copolymerization, as characterized by a linear increase in number average molecular weight (Mn), versus conversion (X) and a narrow molecular weight distribution (Mw/Mn < 1.5). The use of styrene ( 10 mol%) as a "controlling" comonomer for ethyl methacrylate, n-butyl methacrylate and tert-butyl methacrylate resulted in a controlled copolymerization of pseudo-"living" random copolymers characterized by a narrow molecular weight distributions (Mw/Mn = 1.2-1.5). In addition to styrene, 9-(4-vinylbenzyl)-9H-carbazole) (VBK) was used as a "controlling" comonomer for methyl methacrylate and 2-(dimethylamino)ethyl methacrylate, requiring as little as 1-2 mol% VBK relative to methacrylate, resulting in a controlled pseudo-"living" polymerization. In the second part of the thesis, NMP was utilized to control the copolymer microstructure. When using a non-equimolar feed of maleic anhydride (MA) and styrene (S), the synthesis of poly(MA-alt-S)-b-poly(S) block copolymers characterized by narrow molecular weight distributions (Mw/Mn = 1.3) where one block consisted of alternating MA and S monomers, was possible when the polymerization temperature was kept below 90 C. Finally a poly(ethylene-co-butylene)-SG12 initiator was synthesized and was used to successfully polymerize S and S/MA mixtures. The final poly(ethylene-co-butylene)-poly(MA-alt-S)2 block copolymers were tested as compatibilizers in blends with nylon-6.L'utilisation de la polymèrisation radicale contrôlée en présence de radicaux nitroxyde (NMP) a débuté vers les annèes 1990s. Cette technique est simple et robuste, portant facilement à la synthèse de diverses nouvelles architectures de polymères. Grâce au développement d'initiateurs de deuxième génération basés sur radicaux stables de SG1 et de TIPNO, l'NMP n'est plus limité à la polymérisation des styrènes et peut maintenant homopolymériser une varietée de monoméres tels que des acrylates et des acrylamides. Dans cette thèse, plusieurs développements de l'NMP dus à ces initiateurs de deuxième génération, ont été explorés. L'homopolymérisation des methacrylates, par NMP, a pour consèquence un excés de terminaisons irréversibles en raison de à la concentration élevée de radicaux libres produits au début de la polymérisation. Cependant, une petite quantité de comonomère "contrôlant" peut être utilisée pour contrôler la copolymèrisation, donnant comme résultat une augmentation linéaire de la masse molaire moyenne en nombre (Mn) avec la conversion (X) ainsi que des copolymères qui possèdent une distribution moléculaire étroite (Mw/Mn < 1.5). Le styrène ( 10 mol%) a été utilisé comme comonomère "contrôlant" pour la synthèse du méthacrylate éthylique, le méthacrylate n-butylique et le méthacrylate de tert- butyl. Dans tous les cas la copolymèrisation était contrôlée, donnant comme résultat un copolymère qui est "vivant" et qui possède une distribution moléculaire étroite (Mw/Mn = 1.2-1.5). En ajout du styrène, 9-(4-vinylbenzyl)-9H-carbazole) (VBK) a été employé comme comonomère "contr^olant" pour le méthacrylate méthylique et le méthacrylate de 2-diméthylaminoéthyle, mais cette fois exigeant que 1-2 mol% de VBK par rapport aux méthacrylates, ayant comme résultat une copolymèrisationcontr^olée et des copolymères _naux qui sont "vivants". Dans la deuxième partie de la thèse, NMP a été utilisé pour contrôler la microstructure de divers copolymères. En employant une formulation non-équimolaire d'anhydride maléique (MA) et de styrène (s), la synthèse de blocs copolymères poly(MA-alt-S)-b-poly(S) ayant une distribution moléculaire étroite (Mw/Mn = 1.3) a été réalisée lorsque la température de polymérisation était maintenue en dessous de 90C. Finalement l'initiateur poly(éthyléne-co-butyléne)-SG12 a été synthètisé et employé pour la polymèrisation de S et de mélanges de S/MA. Finalement, des copolymères en bloc poly(éthyléne-co-butyléne)-poly(MA-alt-S)2 ont été examinés comme compatibilisateur de mélanges avec le nylon-6.
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Li, Guang-Zhao. "Synthesis and application of some novel functional polymers via controlled radical polymerization and click chemistry". Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/54118/.
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The objective of this thesis was to prepare thermoresponsive PEG-based homopolymers and copolymers by combination of cobalt-mediated catalytic chain-transfer polymerization (CCTP) and thiol-ene “click” chemistry and prepare well-defined glycopolymers via “living” polymerization and “click” chemistry. The effect of different catalysts for the nucleophilic mediated thiol-ene reaction was investigated using model compounds, both monomers and oligomers obtained by CCTP. Different catalysts, including pentylamine and hexylamine (primary amines), triethylamine (tertiary amine), and two different phosphines, dimethylphenylphosphine (DMPP) and tris(2-carboxyethyl) phosphine (TCEP), were investigated in the presence of different thiols. The optimum reaction conditions for nucleophile mediated thiol-ene click reactions were investigated. Thermoresponsive PEG-based homopolymers and copolymers of OEGMEMA obtained by CCT were modified using thiol-ene click chemistry with a variety of different functional thiol compounds to yield functional thermoresponsive polymers in high yield. The effect of different solvent systems for based catalyzed thiol-ene reaction was investigated in the presence of different functional thiols. The ATRP polymerization of TMS-PgMA and TIPS-PgMA and ROP polymerization of aliphatic polyester were investigated. A maleimide functional initiator was used in order to achieve post conjugation of nanoparticles for drug delivery. Moreover, the disulfide based bifunctional initiator was introduced into the midpoint of the polymer chain, which could break down to afford the corresponding polymer chain with thiol end group under the reducing condition. The thiol-terminated polymer was also post-functionalized via thiol-ene click chemistry. In addition, the aliphatic polycarbonate is a biocompatible and biodegradable polymer, which is widely used in medical and pharmaceutical applications. The subsequent introduction of sugar moiety to the reactive polymer chain via CuAAC click reaction and then the interactions between glycopolymers and lectins were investigated by Surface Plasmon Resonance (SPR) and Quartz Crystal Microbalance with Dissipation (QCM-D). The controlled SET-LRP polymerization of TMS-PgMA and SET-RAFT polymerization PgMA with the intact alkyne at ambient temperature were investigated. A maleimide functional initiator and CPDB, as the chain transfer agent have been employed. The introduction of maleimide moiety was to allow for post polymerization conjugation to peptides via reaction with cysteines. The subsequent introduction of sugar azides to click with the reactive polymer containing alkyne group and the glycopolymers through CuAAC was also investigated. The glycopolymer has been successfully prepared combining the SET-LRP/SET-RAFT and CuAAc click chemistry at ambient temperature.
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Saoud, Fozi. "Superparamagnetic nanoparticles for synthesis and purification of polymers prepared via controlled/"living" radical polymerization (CLRP)". Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/3998.
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Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: Living chains prepared by RAFT polymerization and NMP reactions using Z-carboxylate and Z-phosphate RAFT agents, and X-phosphate NMP initiators, were efficiently attached to the surface of magnetic nanoparticles (MNPs) and used for the separation of dead chains formed in these polymerization reactions prior to the attachment of the RAFT agents and NMP initiators to the surface of MNPs. All the living chains that attach selectively to the surface of MNPs contained RAFT or NMP functionalities, had a low polydispersity index (PDI), and could be reactivated to form new polymer extensions or block copolymers with no detectable deviation from 100% efficiency. RAFT chains prepared by RAFT polymerization using the Z-carboxylate RAFT agent and an excess of free radical initiator were also attached to the surface of MNPs and separated in the presence of an external magnetic field. Separated RAFT-functional chains contained no dead chains formed by combination or disproportionation reactions, but a substantial amount of cross-terminated by-product with a low UV absorbance at 320 nm. The cross-termination of the intermediate radical formed in the RAFT polymerization reactions was also investigated in the monomer-excluded free radical reaction model of polystyryl benzyl-(4-carboxyl dithiobenzoate) and polystyryl ethyl-2-bromoisobutyrate. The Z-carboxylate 3- and 4-arm star polymers (formed by cross-termination reactions) were then efficiently attached to the surface of MNPs and separated from the remainder of the polymer solution. They were separated from MNPs and characterized by 1H and 13C-NMR spectroscopy, and MALDI-ToF-MS. Living chains prepared by a RAFT miniemulsion polymerization reaction using Z-carboxylate RAFT agent were attached to the surface of MNPs and used for the separation of all dead chains and uncontrolled high molecular weight polymer of secondary particle formations occur during a miniemulsion polymerization reaction prior to the attachment. Separated dead chains had high PDI values and contained a significant fraction of uncontrolled high molecular weight polymer that lacked RAFT functionality. Initiator-derived chains formed in RAFT polymerization reactions of styrene (St) and methyl methacrylate (MMA) using phosphate free radical (PFR) initiator were selectively attached to the surface of MNPs and separated from R-group-derived polymer chains in the presence of an external magnetic field. All separated initiator-derived chains contained large fractions of dead chains with weak UV absorbance, and which lacked RAFT functionality, and small fractions of RAFT polymer chains. The separated initiator-derived chains had higher PDI values than the as-prepared polymer in the polymerization of St, but lower PDI values than the as-prepared polymer in the polymerization of MMA. RAFT agents attached to the surface of MNPs by the Z group were used as mediating agents for the synthesis of polymers grafted to the surface of MNPs. The polymers grafted to the surface of MNPs were separated from the solution of the free polymer by applying an external magnetic field. The amounts of the polymers grafted to the surface of MNPs greatly increased as the number of RAFT agents attached to the surface of MNPs decreased. When ethyl acetate was used as solvent, it reached 65% by weight and 50% by number of chains. Separated polymers grafted to the surface of MNPs had high PDI values and contained RAFT functionality. Investigations into the kinetics of the RAFT-mediated polymerization reaction on the surface of MNPs revealed that the polymerization reaction mediated using a RAFT agent attached by its Z group to the surface of MNPs had a faster polymerization rate than that mediated using a free Z group RAFT agent. The molecular weight of the grafted polymer increased linearly with conversion, and the reaction rate was pseudo-first-order.
AFRIKAANSE OPSOMMING: Lewende polimeerkettings, berei deur middel van RAFT-beheerde polimerisasie en NMP reaksies waarin Z-karboksilaat en Z-fosfaat RAFT-verbindings en 'n X-fosfaat NMP afsetter gebruik is, is geheg aan die oppervlaktes van magnetisenanopartikels (MNPs), en gebruik vir die skeiding van dooie kettings wat tydens die RAFT en NMP reaksies gevorm is. Alle lewende kettings wat aan die oppervlakte van die MNPs geheg is, is geskei van die oorblywende polimeeroplossing deur die aanwending van ‗n eksterne magnetise veld. Alle kettings wat selektief aan die oppervlaktes van die MNPs gekoppel is met RAFT of NMP funksionaliteit, het ‗n laë poliverspreidingswaarde (PDI) gehad en kon heraktiveer word om ‗n nuwe polimeerverlengings of blokkopolimere te vorm met geen merkbare afwyking van 100% doeltreffendheid nie. RAFT-kettings wat gedurende RAFT-polimerisasie met 'n Z-karboksilaat RAFT-agent en oormaat vrye-radikaalafsetter berei is, is ook geheg aan die oppervlaktes van MNPs en geskei in die teenwoordigheid van 'n eksterne magnetiese veld. Die geskeide RAFT-funksionele kettings het geen dooie kettings bevat nie (gevorm deur kombinasie reaksies), maar 'n aansienlike hoeveelheid ongekontroleerde hoë molekulêremassa polimeer (met lae UV absorpsie by 320 nm). Die kruis-beëindiging van die intermediêre radikaal wat gevorm is tydens die RAFT-proses is ondersoek in die monomeer-uitsluitende vrye-radikaalreaksiemodel van polistirielbensiel-4-karboksielditiobensoaat en polistirieletiel-2-bromoisobutiraat. Die Z-karboksilaat 3- en 4-arm sterpolimere (gevorm a.g.v. kruis-terminasiereaksies) is effektief geheg aan die oppervlaktes van MNPs en geskei van die res van die polimeeroplossing, en daarna gekarakteriseer met behulp van 1H en 13C KMR, en MALDI-ToF-MS. Lewende kettings, berei m.b.v. RAFT miniemulsiepolimerisasies met 'n Z-karboksilaat RAFT-agent, is geheg aan die oppervlaktes van MNPs en gebruik vir die skeiding van alle dooie kettings en sekondêre partikels wat tydens die reaksie voor die aanhegting gevorm het. Die geskeide dooie kettings wat agtergebly het, het 'n wye PDI getoon en het 'n aansienlike hoeveelheid ongekontroleerde hoë molekulêremassa polimeer, met geen RAFT-funksionaliteit nie, bevat. Afsetterafkomstigekettings wat gevorm is tydens die RAFT polimerisasiereaksies van stireen (St) en metielmetakrilaat (MMA) met 'n fosfaat-vrye vrye-radikaalafsetter is selektief geheg aan die oppervlaktes van MNPs en geskei van R-groep-afkomstige polimeerkettings in die teenwoordigheid van 'n eksterne magnetise veld. Alle geskeide afsetter-afkomstige kettings het 'n groot hoeveelheid dooie kettings gehad (met swak UV absorpsie) en met geen RAFT-funksionalilteit nie, en klein fraksies van RAFT-polimeerkettings. Die geskeide afsetter-afkomstige kettings het hoër PDI waardes gehad as die ('as-prepared') polimeer in die polimerisasie van St, maar laer PDI waardes as die ('as-prepared') polimeer in die polimerisasie van MMA. RAFT-verbindings wat aan die oppervlaktes van die MNPs geheg is deur middel van die Z-groep is as bemiddellingsagente (Eng: mediating agents) gebruik vir die sintese van polimere wat geënt is aan die oppervlakte aan MNPs. Die polimere wat aan die oppervlakte van die MNPs geënt is is geskei van die res van die polimeeroplossing deur die aanwending van ‗n eksterne magnetise veld. Die hoeveelhede van die polimere wat aan die oppervlaktes van die MNPs geënt is het sterk toegeneem namate die aantal RAFT-agente wat aan die oppervlaktes van MNPs geheg is afgeneem het. Wanneer etielasetaat as oplosmiddel gebruik is, was die waardes 55% m.b.t. gewig en 45% m.b.t. die aantal kettings. Die geskeide polimere wat aan die oppervlaktes van MNPs geënt is het hoë PDI getoon en het RAFT-funksionaliteit bevat. Die kinetika van die RAFT-beheerde polimerisasiereaksies van St, wat gebruik maak van ‗n RAFT-agent wat aan die oppervlakte van die MNPs geheg is deur middel van die Z-groep, is ook ondersoek. Die tempo van polimerisasie was vinniger in die geval waarin die RAFT-agent geheg is deur sy Z-groep aan die oppervlakte van die MNPs as die reaksie met 'n RAFT agent met 'n vrye Z-groep. Die molekulêremassas van die entpolimere het liniêr toegeneem met omsetting, en die reaksie was pseudo-eerste-orde.
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El, Achi Nassim. "Photochemical and photoredox reactions in continuous microreactors : application to cycloaddition, controlled polymerization and radical chemistry". Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10044/document.
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Ce travail consiste à étudier différentes réactions photochimiques en dispositifs microfluidiques en utilisant la lumière UV/visible, par le biais de catalyseurs recyclables métalliques et non-métalliques, pour la synthèse organique aux applications pharmaceutiques et industrielles. En outre, l’utilisation des systèmes microfluidiques dans des chemins optiques miniaturisés de 500 µm résultant en une amélioration d’illumination. Les mesures d’actinométrie chimique confirment que ≈ 98% de la lumière émise atteint le mélange de réaction dans un réacteur fluidique Mikroglas® Dwell Device largement utilisé dans la littérature. Différentes réactions de cycloaddition [2 + 2] utilisées en synthèse totale ont été testées en utilisant un sensibilisateur sous UV. La réaction est quantitative après 2 h contre 47% après 10 h en batch. La polymérisation radicalaire contrôlée (ATRP) a été étudiée en utilisant le catalyseur photorédox éosine Y sous illumination à base de LED vertes. Six heures d'irradiations sont suffisantes pour fournir des polymères mono dispersés aux applications variables (plastiques, latex ...). Ces catalyseurs non-métalliques sont d'une importance capitale car ils sont plus respectueux de l'environnement. Former de nouvelles liaisons C-C et C-O est le cœur de la synthèse organique. L’utilisation de sources LEDs UV et d’un catalyseur photorédox nous a permis de former des produits d'addition (> 99%), à partir d’une part de sels de trifluoroborates et de TEMPO ou d’accepteurs de Michaël, d’autre part, après 2,5 min d'irradiation contre 8-24 h en batch.Ce travail montre clairement l’apport des systèmes microfluidiques pour l’accélération de réactions photochimiquesIn order to mimic nature’s highly energy efficient photosynthesis reaction, this work focuses on photochemical reactions using UV/visible light, metal based recyclable catalysts and metal free catalysts in flow to synthesize organic material that have pharmaceutical and industrial applications. The utilized microfluidic systems have small path lengths (500 μm) resulting in improved illumination. Using chemical actinometry, it was shown that ≈ 98% of the light supplied reached the reaction mixture inside the widely used Mikroglas® Dwell device. [2+2] cycloaddition, used in total synthesis, was tested in flow using a sensitizer under UV. The optimized reaction was quantitative after 2 h vs. 47% after 10 h in literature’s batch system. Metal free ATRP was assessed using the commercial Eosin Y in flow with green LEDs. Only 6 h of irradiation were enough to give narrow dispersed polymers that have wide applications (plastics, latex…). Metal free catalysts are of critical importance as they are more ecofriendly. Forming new C-C and C-O bonds is the heart of organic synthesis. Using UV LEDs and a photoredox catalyst, adducts of trifluoroborate salts with TEMPO and with Michaël acceptors were obtained (>99%) after only 2.5 min of irradiation in flow compared to 8-24 h in batch. Our results highlight the impact of miniaturization on accelerating photochemical reactions. Less time and energy usage, improved yields and strictly linear kinetic graphs are main features of flow technology. In addition, miniaturization requires less safety precautions rendering it favorable for large scale industry. This work supports considering the microfluidic technology for greener industrial systems
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Radzinski, Scott Charles. "Synthesis of Bottlebrush Polymers Using the Grafting-Through and Transfer-To Methods". Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/77574.
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Bottlebrush polymers are interesting topologies that have become increasingly relevant in various applications including rheology modifiers, super-soft elastomers, photonic crystals, anti-fouling coatings, the in vivo delivery of therapeutic agents, and as promising substrates in lithographic printing. These macromolecules are comprised of numerous polymeric side-chains densely grafted to a polymer backbone. The densely grafted nature of bottlebrush polymers results in steric repulsion between neighboring polymer chains, forcing these macromolecules to adopt a chain-extended conformation. Although these remarkable macromolecules have a many different applications, the transformative potential of the bottlebrush polymer topology has not been realized because the synthesis of high molecular weight bottlebrush polymers is challenging. This dissertation focusses on improving the synthesis of these large macromolecules using the grafting-through strategy in the first section and the transfer-to strategy in the second section.
For the first time the effect of anchor group chemistry—the configuration of atoms linking the polymer to a polymerizable norbornene—was studied on the kinetics of ring-opening metathesis polymerization (ROMP) of macromonomers (MMs) initiated by Grubbs 3rd generation catalyst. A variance in the rate of propagation of >4-fold between similar MMs with different anchor groups was observed. This phenomenon was conserved across all MMs tested, regardless of solvent, molecular weight (MW), or repeat unit identity. Experimental and computational studies indicated that the rate differences likely resulted from a combination of varying steric demands and electronic structure among the different anchor groups. This new insight will allow others to achieve high MM conversion and prepare pure, high MW bottlebrush polymers by ROMP grafting-through.
The second section of this dissertation deals with a little studied bottlebrush synthesis technique called the transfer-to method. This method is a hybrid of the grafting-from and grafting-to approaches in which the growing polymer side chains detach from the backbone, propagate freely in solution, and then reattach to the backbone in a chain transfer step. Several parameters were investigated to determine optimal conditions for this process. This study provides for the first time a guide to use the transfer-to method to produce high purity bottlebrush polymers with controllable backbone and side chain length.Ph. D.
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Nozari, Samira. "Towards understanding RAFT aqueous heterophase polymerization". Phd thesis, Universität Potsdam, 2005. http://opus.kobv.de/ubp/volltexte/2005/580/.
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Reversible addition-fragmentation transfer (RAFT) was used as a controlling technique for studying the aqueous heterophase polymerization. The polymerization rates obtained by calorimetric investigation of ab initio emulsion polymerization of styrene revealed the strong influence of the type and combination of the RAFT agent and initiator on the polymerization rate and its profile. The studies in all-glass reactors on the evolution of the characteristic data such as average molecular weight, molecular weight distribution, and average particle size during the polymerization revealed the importance of the peculiarities of the heterophase system such as compartmentalization, swelling, and phase transfer. These results illustrated the important role of the water solubility of the initiator in determining the main loci of polymerization and the crucial role of the hydrophobicity of the RAFT agent for efficient transportation to the polymer particles. For an optimum control during ab-initio batch heterophase polymerization of styrene with RAFT, the RAFT agent must have certain hydrophilicity and the initiator must be water soluble in order to minimize reactions in the monomer phase.
An analytical method was developed for the quantitative measurements of the sorption of the RAFT agents to the polymer particles based on the absorption of the visible light by the RAFT agent. Polymer nanoparticles, temperature, and stirring were employed to simulate the conditions of a typical aqueous heterophase polymerization system. The results confirmed the role of the hydrophilicity of the RAFT agent on the effectiveness of the control due to its fast transportation to the polymer particles during the initial period of polymerization after particle nucleation. As the presence of the polymer particles were essential for the transportation of the RAFT agents into the polymer dispersion, it was concluded that in an ab initio emulsion polymerization the transport of the hydrophobic RAFT agent only takes place after the nucleation and formation of the polymer particles. While the polymerization proceeds and the particles grow the rate of the transportation of the RAFT agent increases with conversion until the free monomer phase disappears.The degradation of the RAFT agent by addition of KPS initiator revealed unambigueous evidence on the mechanism of entry in heterophase polymerization. These results showed that even extremely hydrophilic primary radicals, such as sulfate ion radical stemming from the KPS initiator, can enter the polymer particles without necessarily having propagated and reached a certain chain length. Moreover, these results recommend the employment of azo-initiators instead of persulfates for the application in seeded heterophase polymerization with RAFT agents.
The significant slower rate of transportation of the RAFT agent to the polymer particles when its solvent (styrene) was replaced with a more hydrophilic monomer (methyl methacrylate) lead to the conclusion that a complicated cooperative and competitive interplay of solubility parameters and interaction parameter with the particles exist, determining an effective transportation of the organic molecules to the polymer particles through the aqueous phase. The choice of proper solutions of even the most hydrophobic organic molecules can provide the opportunity of their sorption into the polymer particles. Examples to support this idea were given by loading the extremely stiff fluorescent molecule, pentacene, and very hydrophobic dye, Sudan IV, into the polymer particles.
Finally, the first application of RAFT at room temperature heterophase polymerization is reported. The results show that the RAFT process is effective at ambient temperature; however, the rate of fragmentation is significantly slower. The elevation of the reaction temperature in the presence of the RAFT agent resulted in faster polymerization and higher molar mass, suggesting that the fragmentation rate coefficient and its dependence on the temperature is responsible for the observed retardation.
Um neue Materialien mit außergewöhnlichen Eigenschaften zu erstellen, muss man in der Lage sein, die Struktur der Moleküle zu kontrollieren, aus denen die Materialien bestehen. Für das Maßschneidern solcher neuer Eigenschaften besitzen Polymere ein großes Potenzial: Dies sind sehr lange Moleküle, die aus einer großen Zahl von kleineren Einheiten aufgebaut sind. Proteine und DNS sind Beispiele für natürliche Polymere; Plastik und Gummi sind Beispiele für künstliche Polymere. Letztere werden üblicherweise durch das Zusammenfügen einer Reihe von kleineren Molekülen, den Monomeren, hergestellt. Schon lange versuchen Wissenschaftler, die Anordnung, Anzahl und Art dieser Monomere zu kontrollieren, die sich in der Struktur der Polymermoleküle widerspiegeln. Die gebräuchlichste Methode zur kommerziellen Produktion von Polymeren ist die so genannte freie radikalische Polymerisation. Die Strukturkontrolle durch diese Methode ist jedoch relativ schwierig und wurde maßgeblich erst im letzten Jahrzehnt entwickelt. Trotz der Existenz einiger effektiver Kontrollmethoden ist ihre industrielle Anwendung bislang sehr beschränkt, weil sie nicht für die Emulsionspolymerisation verwendbar sind. Die Emulsionspolymerisation ist die gängigste Technik in der industriellen Produktion von Polymeren. Es handelt sich dabei um ein vergleichsweise umweltfreundliches Verfahren, denn es werden keine organischen Lösungsmittel verwendet. Stattdessen dient Wasser als Lösungsmittel, in dem die Polymere in Form von kleinen, fein verteilten Partikeln vorliegen. In der Natur kommt dieses Prinzip beispielsweise in Pflanzen bei der Bildung von Kautschuk - allgemein als Latex bezeichnet - vor. Schließlich ist die Emulsionspolymerisation einfach durchzuführen: Das Produkt ist in vielen Fällen gebrauchsfertig, und es gibt viele technische Vorteile im Vergleich zu anderen Herstellungsprozessen.
Doch bevor die Probleme beim Einsatz von Kontrollmethoden in der Emulsionspolymerisation gelöst werden können, müssen erst ihre Ursachen geklärt werden. Dies ist eine unverzichtbare Vorraussetzung zum Übertragen von Forschungsergebnissen auf das tägliche Leben.
Ziel dieser Arbeit ist die Untersuchung der Probleme, die für die kontrollierte radikalische Polymerisation in Emulsion von Bedeutung sind. Die wichtigste Fragestellung in der Emulsionspolymerisation zielt auf die Löslichkeit der Reaktionskomponenten in den verschiedenen Phasen, wie z.B. in Wasser oder in den Polymerpartikeln. Die Kontrollmethode der Wahl für diese Arbeit ist "Reversibler Additions-Fragmentierungs Transfer" (RAFT). Die RAFT-Methode ist die modernste Kontrollmethode, und sie ist für viele Reaktionsbedingungen und viele Arten von Monomeren anwendbar.
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Jones, Jason William. "Enhanced Architectural and Structural Regulation Using Controlled Free Radical Polymerization Techniques; Supramolecular Assemblies: Pseudorotaxanes and Polypseudorotaxanes". Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/31766.
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Due in large part to the growth and development of reliable surface characterization techniques, as well as to advances in the physical and chemical techniques used to modify surfaces, the technology of surface modification has seen rapid expansion over the past two decades. A major thrust of this research is the growth of controlled/"living" polymeric brushes from the surface of various substrates, an advance that promises to be a facile and reproducible way of altering surface properties. A unique initiator bearing ATRP (atom transfer radical polymerization), cleavage, and condensation functionalities was prepared and attached to the hydrolyzed surface of silica gel. Preliminary results indicate that control of reversibly terminated grafts of varying degrees of polymerization with polydispersity indices approaching 1.5 can be readily achieved-significant findings in the quest to design desired surface characteristics.
Important physical characteristics may also be altered by way of varying molecular topologies. In the second major research thrust, the use of self-assembly to construct such topologies in the form of pseudorotaxanes fashioned from diverse macrocycles with multifarious guest ions is discussed. While the underlying goal was to investigate and understand the mode of complexation based on such environmental factors as substituent affects and neighboring group influences, new insight was gained on the synthetic manipulation of cooperative events-events that freely occur in nature. The complexation behavior of several functionalized bis-(meta-phenylene)-32-crown-10 macrocycles with various paraquat guest moieties was. As expected, studies indicated that electron-donating substituents on the crown ether drive association, a likely result of increased p -p interactions among host and guest species. The association between a bicyclic macrocycle and dimethyl paraquat was also investigated. Not surprisingly, binding of paraquat by the bicyclic was much stronger than the binding found in analogous macrocycles. Lastly, the endgroup functionalization of poly(propyleneimine) dendrimers with two crown ether macrocycles was performed and the complexation with host-specific guests studied. Curiously, two extreme binding regimes were found: the larger 32-membered crown ether assembly displayed anti-cooperative behavior upon complexation with paraquat, while the smaller 24-membered macrocyclic system exhibited cooperative effects with 2o ammonium ions. These cooperative results are among the very first described for non-biological systems and hint at their potential use in developing highly efficient, synthetically designed supramolecular systems.Master of Science
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Krivorotova, Tatjana. "Synthesis of polyelectrolytes contaiting poly(ethylene oxide) side chains by living radical polymerization". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20100915_162344-10990.
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The main goal of this work was to synthesize polyelectrolyte brushes containing poly(ethylene oxide) side chains by living polymerization. Brush-like macromolecules are unique polymer molecules whose conformation and physical properties are controlled by steric repulsion of densely grafted side chains. Molecules can be either flexible or stiff, depending on the grafting density and the length of the side chains. Polymerization of macromonomers is one of the most useful ways to prepare brush copolymers. However, with the macromonomer method, the distribution of the spacing of the side chains cannot be entirely controlled which along with broad and multimodal molecular weight distribution makes these polymers heterogeneous. These problems were considered to be overcome with the use of controlled/living polymerization.
Conventional free-radical and RAFT copolymerization of poly(ethylene oxide) substituent containing methacrylate macromonomers, PEO5MEMA and PEO45MEMA, with methacrylic acid (MAA) was studied by the use of 1H NMR spectroscopy for an analysis of residual monomers. RAFT copolymerization of PEO45MEMA and MAA enabled to synthesize comb copolymers with low composition distribution and more homogeneous distribution of PEO side chains along the mainchain. Amphiphilic non-ionic blockcopolymers poly(lauryl methacrylate) (PLMA) – P(PEOnMEMA) and amphiphilic anionic blockcopolymers PLMA – PMAA were prepared by the RAFT method, and their properties in aqueous and THF... [to full text]Vienas iš šiuolaikinės polimerų chemijos uždavinių – gauti numatytos molekulinės masės ir architektūros polimerines medžiagas. Neseniai buvo sukurti nauji radikalinės polimerizacijos metodai, kurie priskiriami gyvybingajai (valdomai) polimerizacijai (GRP). Makromonomerų (MM) gyvybingoji radikalinė polimerizacija yra efektyvus būdas gauti šepetinius (cilindrinius) polimerus). Šepetiniai polimerai – tai makromolekulės, kuriose prie pagrindinės polimerinės grandinės prijungta daug šoninių mažesnės molekulinės masės polimerinių (oligomerinių) grandinių. Dėl tarp šoninių grandinių esančių erdvinės stūmos jėgų tokios makromolekulės įgauna neįprastų savybių, pvz., standumą, cilindrinę formą, didelį segmentų tankį. Pagrindinis šio darbo tikslas buvo susintetinti norimos sudėties šepetinius polielektrolitinius polimerus, sudarytus iš krūvį turinčios poli(met)akrilato pagrindinės grandinės ir šoninių polietilenoksido grandinių, ir ištirti jų savybes. Svarbiausieji šio darbo rezultatai, atspindintys jo naujumą, originalumą ir svarbą: Pirmą kartą nuodugniai ištirta metakrilo rūgšties (MAR) ir dviejų skirtingų molekulinių masių polietilenoksido metakrilatų PEOnMEMA (n = 5, 45) kopolimerizacija įprastiniu radikaliniu ir RAFT metodais. Sukurta metodika PEO makromonomerų kopolimerizacijos kinetikai tirti, užrašant 1H BMR spektrus in situ ir įvertinant likutinę monomerų koncentraciją reakcijos mišinyje bei momentinę kopolimero sudėtį iki gilių konversijų. Netiesiniu kintamųjų paklaidų metodu... [toliau žr. visą tekstą]
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Allen, Michael H. Jr. "Imidazole-Containing Polymerized Ionic Liquids for Emerging Applications: From Gene Delivery to Thermoplastic Elastomers". Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/49593.
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Novel imidazole-containing polyelectrolytes based on poly(1-vinylimidazole) (poly(1VIM)) were functionalized with various hydroxyalkyl-substituents to investigate the influence of charge density and hydrogen bonding on nonviral DNA delivery. Copolymers with higher charge densities exhibited increased cytotoxicity, whereas increased hydroxyl concentrations remained nontoxic. DNA binding affinity increased with increased charge densities and increased hydroxyl content. Dynamic light scattering determined the copolymers which delivered DNA most effectively maintained an intermediate binding affinity between copolymer and DNA. Copolymers containing higher charge densities or hydroxyl concentrations bound DNA too tightly, preventing its release inside the cell. Copolymers with lower charge densities failed to protect the DNA from enzymatic degradation. Tuning hydrogen bonding concentration allowed for a less toxic and more effective alternative to conventional, highly charged polymers for the development of nonviral DNA delivery vehicles. The synthesis of amine-containing imidazolium copolymers functionalized with low concentrations of folic acid enabled the investigation of additional polymer modifications on nonviral gene delivery.
Functionalization of 1VIM with various hydroxyalkyl and alkyl groups and subsequent conventional free radical polymerization afforded a series of imidazolium-containing polyelectrolytes. Hydroxyl-containing homopolymers exhibited higher thermal stabilities and lower Tg's compared to the respective alkyl-analog. X-ray scattering demonstrated the polarity of the hydroxyl group facilitated solvation of the electrostatic interactions disrupting the
nanophase-separated morphology observed in the alkylated systems. Impedance spectroscopy determined hydroxyl-containing imidazolium homopolymers displayed higher ionic conductivities compared to the alkyl-containing analogs which was attributed to increased solvation of electrostatic interactions in the hydroxyl analogs.
Beyond functionalizing 1VIM monomers and homopolymers to tailor various properties, the synthesis of novel architectures in a controlled fashion remains difficult due to the radically unstable N-vinyl propagating radical. The regioisomer 4-vinylimidazole (4VIM) contains two resonance structures affording increased radical stability of the propagating radical. Nitroxide-mediated polymerization (NMP) and atom transfer radical polymerization (ATRP) failed to control 4VIM homopolymerizations; however, reversible addition-fragmentation chain transfer (RAFT) demonstrated unprecedented control. Linear pseudo-first order kinetics were observed and successful chain extension with additional 4VIM suggested preservation of the trithiocarbonate functionality.
Effectively controlling the polymerization of 4VIM enabled the design of amphoteric block copolymers for emerging applications. The design of ABA triblock copolymers with 4VIM as a high Tg supporting outer block and di(ethylene glycol) methyl ether methacrylate (DEGMEMA) as a low Tg, inner block, required the development of a new difunctional RAFT chain transfer agent (CTA). The difunctional CTA successfully mediated the synthesis of the ABA triblock copolymer, poly(4VIM-b-DEGMEMA-b-4VIM), which exhibited microphase separated morphologies. The amphoteric nature of the imidazole ring required substantially lower concentrations of outer block incorporation compared to traditional triblock copolymers to achieve similar mechanical properties and microphase separated morphologies.Ph. D.
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Ott, Marcus [Verfasser], Markus [Akademischer Betreuer] Biesalski e Annette [Akademischer Betreuer] Andrieu-Brunsen. "Tailor-made cellulose graft copolymers by controlled radical polymerization techniques / Marcus Ott ; Markus Biesalski, Annette Andrieu-Brunsen". Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2017. http://d-nb.info/112415521X/34.
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Sidi, Zhao. "Synthesis, Characterization and High-throughput Screening of Photoiniferter/RAFT Agent for Well-controlled Radical Polymerization of Block Copolymers". University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1555435272696644.
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Scholte, Jon Paul. "Effects of prepolymer structure on photopolymer network formation and thermomechanical properties". Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5624.
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Photopolymerization is a growing field within the realms of polymer and material science. With diverse applications, ranging from coatings and adhesives to newer technologies such as 3D printing photopolymerization continues to increase its prevalence and influence. This research examines fundamental structure property relationships between large prepolymer structures within a formulation and the resulting impact on thermo-mechanical properties in photocurable resins. Most prepolymer molecules utilize a “one pot” synthesis with little to no control over the placement of photoreactive moieties such as epoxies and (meth) acrylates. We have utilized novel prepolymer molecules synthesized using controlled radical polymerization to allow direct control over the placement of reactive groups. The ability to control the location of reactive groups in prepolymer molecules can also lead to the formation of multiple domains within the resulting photocured thermoset. This separation is achieved by concentrating the reactive groups at specific locations in the prepolymer backbone, e.g. at the end or near the center of the prepolymer molecule. The nonreactive groups may form one domain within the thermoset network while the reactive portion of the prepolymer forms a second phase with reactive diluent molecules. Additionally, various architectures allow greater control over polymer network formation and crosslink density. Through these manipulations of macromolecular architecture, we have been able to manipulate various thermo-mechanical properties. Using various architectured prepolymer, we have been able to generate materials with multiple glass transitions while also increasing the rate of reaction and total conversion as compared to randomly functionalized control formulations.
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Lin, Anna. "Nitroxide-mediated photo-polymerization". Electronic Thesis or Diss., Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0264.
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De nos jours, la photopolymérisation est devenue un procédé important dans le domaine de la science des polymères. Cette méthode présente de nombreux avantages : la rapidité de la réaction, l‘aspect environnemental (formation limitée de composés organiques volatils et possibilité de réaction à température ambiante) ou encore un contrôle spatial et temporel. Ce mode d‘activation photochimique appliqué pendant les dernières décennies aux techniques de polymérisation radicalaire contrôlée telles que l‘ATRP, la RAFT ou la NMP permet de contrôler les propriétés des polymères mais aussi la préparation de polymères à blocs. Parmi ces techniques, la photopolymérisation contrôlée par les nitroxydes (NMP²) nécessite l‘utilisation d‘une alcoxyamine photosensible dont un groupement chromophore est porté par un nitroxyde. Dans ce manuscrit, nous présentons aussi bien la préparation d‘alcoxyamines photosensibles que les études de leurs propriétés photochimiques analysées par spectroscopie d‘absorption et par expériences de résonance paramagnétique électronique. Nous avons évalué les capacités de polymérisation des meilleurs candidats obtenus dans des conditions de NMP². Enfin, une autre méthode a été testée en effectuant une réaction de NMP² à partir d‘alcoxyamines produites par ESCP (Enhanced Spin Capturing Polymerization) ou par NMRC (Nitrone-Mediated Radical Coupling)Nowadays, photopolymerization has become an important process in the field of polymer science. This method presents several advantages such as the speed of the reaction, the environmental-friendly side (limited formation of released volatile organic compound and possibility of a reaction at room temperature) but also a spatial and temporal control. This photochemical approach applied in the past decades to controlled radical polymerization techniques such as ATRP, RAFT or NMP enable the control of polymer properties but also the preparation of block polymers. Among these techniques, the Nitroxide-Mediated Photopolymerization (NMP²) requires the use of a photosensitive alkoxyamine which has a chromophore group on the nitroxide moiety. In this manuscript, we present both the synthesis of photosensitive alkoxyamines and the studies of their photochemical properties investigated by absorption spectroscopy and by electron spin resonance experiments. We evaluated the polymerization abilities of the best obtained candidates. Finally, another approach has been tested to perform a reaction of NMP² from alkoxyamines made by ESCP (Enhanced Spin Capturing Polymerization) or via NMRC (Nitrone-Mediated Radical Coupling)
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Dréan, Mathilde. "Controlled synthesis of polyvinylamine-based (co)polymers for gene transfection". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066444.
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Le transfert de gènes consiste en l’introduction d’acides nucléiques au sein de cellules afin de modifier leur activité dans un but essentiellement thérapeutique. Pour préserver le matériel génétique de toute dégradation, il faut recourir à des vecteurs. Parmi ceux-ci, les polymères cationiques sont très prometteurs, en particulier, la polyéthylènimine, considérée comme le vecteur non-viral de référence. Néanmoins, il présente une cytotoxicité élevée. Ainsi, de nombreuses recherches ont pour but d’identifier et de développer de nouveaux polymères combinant efficacité de transfection et haute viabilité cellulaire. Cette thèse vise le développement de méthodes d’ingénierie macromoléculaire donnant accès à une large gamme de dérivés à base de polyvinylamine et l’évaluation de leurs performances en tant que vecteurs de transfection. Différentes techniques de polymérisation radicalaire conventionnelle et contrôlée ont été mises au point afin de synthétiser des (co)polymères à base de polyvinylamine constitués d’amines primaires et secondaires. L’efficacité du transfert d’ADN plasmidique et la viabilité cellulaire ont été évaluées sur des cellules HeLa. L’influence de différents paramètres macromoléculaires sur les performances de transfection a été investiguée. Cette étude a permis de démontrer que certains dérivés de polyvinylamine possédaient une efficacité de transfection aussi élevée que la PEI tout en étant moins toxique. De manière générale, ce travail rend compte du haut potentiel des (co)polyvinylamines en tant que vecteurs pour le transfert de gènesGene transfection consists in the introduction of genetic materials (DNA or RNA) in cells in order to modulate the cell activity, with therapeutic purposes in most cases. To deliver the genetic materials into cells without degradation, vectors are necessary. Among them, cationic polymers are promising candidates. For instance, polyethylenimine has emerged as a gold standard due to its high transfection ability. Nevertheless, this polymer exhibits high cytotoxicity, and current research aims at identifying and developing new polymers with improved cell viability and high gene transfer efficiency. In this context, the aim of this thesis was to develop efficient macromolecular engineering tools to prepare a library of polyvinylamine-containing (co)polymers and to evaluate their performances as DNA carriers. Consequently, free radical polymerization (FRP) and controlled radical polymerization (CRP) have been explored and a series of (co)polyvinylamines, containing primary and secondary amines, as well as vinylimidazole and guanidine moieties, have been synthesized. The transfection efficiency of plasmid DNA (pDNA) and cell viability were evaluated on HeLa cells. The influence of different macromolecular parameters such as molar mass, molar mass distribution and composition, was also studied. The most promising polymers for pDNA transfection were also tested for siRNA delivery and on other cell lines. Overall, several polymers were competitive with PEI regarding the transfection efficiency but were much less toxic. (Co)polyvinylamines, which have often been disregarded for transfection purposes, should definitely be considered as valuable gene carriers
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Dommanget, Cédric. "Polymérisation radicalaire contrôlée : le défi de l'éthylène". Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10216/document.
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Les travaux présentés dans cette thèse portent sur le contrôle de la polymérisation radicalaire de l'éthylène à basse pression (200 bar) et basse température (70 °C) et sur la synthèse de copolymères à blocs contenant au moins un segment de polyéthylène. Quatre techniques de polymérisation, couramment utilisées en ingénierie macromoléculaire, ont été étudiées : NMP, CMRP, RAFT/MADIX et ESCP. Nos études sur le nitroxyde SG1 (NMP) et le bis(acétylacétonate) de cobalt (CMRP) ont montré que ces composés sont inefficaces pour contrôler la polymérisation de l'éthylène. Un comportement inattendu du bis(acétylacétonate) de cobalt a cependant été mis en évidence. Il semblerait que ces complexes de cobalt favorisent les réactions de couplage entre les radicaux propagateurs. En revanche, la première polymérisation radicalaire contrôlée de l'éthylène a été atteinte grâce à l'utilisation de xanthates (RAFT/MADIX). Les polyéthylènes synthétisés possèdent des masses molaires qui augmentent linéairement avec la conversion et des dispersités faibles. Le caractère pseudo-vivant de la réaction a été démontré par la synthèse de copolymères à blocs poly(acétate de vinyle)-b-polyéthylène. L'utilisation de nitrones (ESCP) a également permis l'introduction d'une fonction réactive au centre des chaînes de polyéthylène et la synthèse de copolymères triblocs de type ABA, où les blocs latéraux A sont en polystyrène ou polyacrylate et le bloc central B est en PolyéthylèneThe work presented in this thesis displays the controlled radical polymerization of ethylene at low temperature (70 °C) and low pressure (200 bar) and the synthesis of block copolymers featuring polyethylene segments. Four polymerization techniques, commonly used in macromolecular engineering, were studied: NMP, CMRP, RAFT/MADIX and ESCP. Our investigation of the use of SG1 nitroxide (NMP) and cobalt (II) acetylacetonate (CMRP) as controlling agents demonstrated their inability to control the polymerization of ethylene. Nonetheless, an unexpected reaction with cobalt (II) acetylacetonate was observed. The coupling reaction between propagating radicals appeared to be favored by the presence of this compound. On the other hand, the first controlled polymerization of ethylene was successfully achieved by using xanthate (RAFT/MADIX). A linear increase of molecular weight with conversion and low polydispersities were observed for the produced polyethylenes. The reaction was demonstrated to be a pseudo-living polymerization by the synthesis of block copolymers poly(vinyl acetate)-b-polyethylene. In addition, midchain-functionalized polyethylenes and ABA type block copolymers, with polystyrene or polyacrylate as the A block and polyethylene as the B block, were also prepared using nitrone based polymerization technique (ESCP)
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Kir, Onur [Verfasser], Wolfgang H. [Akademischer Betreuer] Binder e Guido [Akademischer Betreuer] Kickelbick. "Surface initiated polymerization of isoprene from silica nano- and glass particles via living anionic and controlled radical polymerization techniques / Onur Kir. Betreuer: Wolfgang H. Binder ; Guido Kickelbick". Halle, Saale : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2013. http://d-nb.info/1050977734/34.
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AllenJr, Michael Harry. "Imidazole-Containing Polymerized Ionic Liquids for Emerging Applications: From Gene Delivery to Thermoplastic Elastomers". Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/49593.
Texto completo da fonteResumo:
Novel imidazole-containing polyelectrolytes based on poly(1-vinylimidazole) (poly(1VIM)) were functionalized with various hydroxyalkyl-substituents to investigate the influence of charge density and hydrogen bonding on nonviral DNA delivery. Copolymers with higher charge densities exhibited increased cytotoxicity, whereas increased hydroxyl concentrations remained nontoxic. DNA binding affinity increased with increased charge densities and increased hydroxyl content. Dynamic light scattering determined the copolymers which delivered DNA most effectively maintained an intermediate binding affinity between copolymer and DNA. Copolymers containing higher charge densities or hydroxyl concentrations bound DNA too tightly, preventing its release inside the cell. Copolymers with lower charge densities failed to protect the DNA from enzymatic degradation. Tuning hydrogen bonding concentration allowed for a less toxic and more effective alternative to conventional, highly charged polymers for the development of nonviral DNA delivery vehicles. The synthesis of amine-containing imidazolium copolymers functionalized with low concentrations of folic acid enabled the investigation of additional polymer modifications on nonviral gene delivery. Functionalization of 1VIM with various hydroxyalkyl and alkyl groups and subsequent conventional free radical polymerization afforded a series of imidazolium-containing polyelectrolytes. Hydroxyl-containing homopolymers exhibited higher thermal stabilities and lower Tg\'s compared to the respective alkyl-analog. X-ray scattering demonstrated the polarity of the hydroxyl group facilitated solvation of the electrostatic interactions disrupting the
nanophase-separated morphology observed in the alkylated systems. Impedance spectroscopy determined hydroxyl-containing imidazolium homopolymers displayed higher ionic conductivities compared to the alkyl-containing analogs which was attributed to increased solvation of electrostatic interactions in the hydroxyl analogs.
Beyond functionalizing 1VIM monomers and homopolymers to tailor various properties, the synthesis of novel architectures in a controlled fashion remains difficult due to the radically unstable N-vinyl propagating radical. The regioisomer 4-vinylimidazole (4VIM) contains two resonance structures affording increased radical stability of the propagating radical. Nitroxide-mediated polymerization (NMP) and atom transfer radical polymerization (ATRP) failed to control 4VIM homopolymerizations; however, reversible addition-fragmentation chain transfer (RAFT) demonstrated unprecedented control. Linear pseudo-first order kinetics were observed and successful chain extension with additional 4VIM suggested preservation of the trithiocarbonate functionality.
Effectively controlling the polymerization of 4VIM enabled the design of amphoteric block copolymers for emerging applications. The design of ABA triblock copolymers with 4VIM as a high Tg supporting outer block and di(ethylene glycol) methyl ether methacrylate (DEGMEMA) as a low Tg, inner block, required the development of a new difunctional RAFT chain transfer agent (CTA). The difunctional CTA successfully mediated the synthesis of the ABA triblock copolymer, poly(4VIM-b-DEGMEMA-b-4VIM), which exhibited microphase separated morphologies. The amphoteric nature of the imidazole ring required substantially lower concentrations of outer block incorporation compared to traditional triblock copolymers to achieve similar mechanical properties and microphase separated morphologies.
Ph. D.
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Lu, Yangtian. "Synthesis of structurally controlled hyperbranched polymers through the design of new monomers with hierarchical reactivity". Kyoto University, 2019. http://hdl.handle.net/2433/243314.
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Dréan, Mathilde. "Controlled synthesis of polyvinylamine-based (co)polymers for gene transfection". Electronic Thesis or Diss., Paris 6, 2016. http://www.theses.fr/2016PA066444.
Texto completo da fonteResumo:
Le transfert de gènes consiste en l’introduction d’acides nucléiques au sein de cellules afin de modifier leur activité dans un but essentiellement thérapeutique. Pour préserver le matériel génétique de toute dégradation, il faut recourir à des vecteurs. Parmi ceux-ci, les polymères cationiques sont très prometteurs, en particulier, la polyéthylènimine, considérée comme le vecteur non-viral de référence. Néanmoins, il présente une cytotoxicité élevée. Ainsi, de nombreuses recherches ont pour but d’identifier et de développer de nouveaux polymères combinant efficacité de transfection et haute viabilité cellulaire. Cette thèse vise le développement de méthodes d’ingénierie macromoléculaire donnant accès à une large gamme de dérivés à base de polyvinylamine et l’évaluation de leurs performances en tant que vecteurs de transfection. Différentes techniques de polymérisation radicalaire conventionnelle et contrôlée ont été mises au point afin de synthétiser des (co)polymères à base de polyvinylamine constitués d’amines primaires et secondaires. L’efficacité du transfert d’ADN plasmidique et la viabilité cellulaire ont été évaluées sur des cellules HeLa. L’influence de différents paramètres macromoléculaires sur les performances de transfection a été investiguée. Cette étude a permis de démontrer que certains dérivés de polyvinylamine possédaient une efficacité de transfection aussi élevée que la PEI tout en étant moins toxique. De manière générale, ce travail rend compte du haut potentiel des (co)polyvinylamines en tant que vecteurs pour le transfert de gènesGene transfection consists in the introduction of genetic materials (DNA or RNA) in cells in order to modulate the cell activity, with therapeutic purposes in most cases. To deliver the genetic materials into cells without degradation, vectors are necessary. Among them, cationic polymers are promising candidates. For instance, polyethylenimine has emerged as a gold standard due to its high transfection ability. Nevertheless, this polymer exhibits high cytotoxicity, and current research aims at identifying and developing new polymers with improved cell viability and high gene transfer efficiency. In this context, the aim of this thesis was to develop efficient macromolecular engineering tools to prepare a library of polyvinylamine-containing (co)polymers and to evaluate their performances as DNA carriers. Consequently, free radical polymerization (FRP) and controlled radical polymerization (CRP) have been explored and a series of (co)polyvinylamines, containing primary and secondary amines, as well as vinylimidazole and guanidine moieties, have been synthesized. The transfection efficiency of plasmid DNA (pDNA) and cell viability were evaluated on HeLa cells. The influence of different macromolecular parameters such as molar mass, molar mass distribution and composition, was also studied. The most promising polymers for pDNA transfection were also tested for siRNA delivery and on other cell lines. Overall, several polymers were competitive with PEI regarding the transfection efficiency but were much less toxic. (Co)polyvinylamines, which have often been disregarded for transfection purposes, should definitely be considered as valuable gene carriers
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Östmark, Emma. "Tuning Properties of Surfaces and Nanoscopic Objects using Dendronization and Controlled Polymerizations". Doctoral thesis, KTH, Fiber- och polymerteknik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4550.
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In this study, dendronization and grafting via controlled polymerization techniques, atom transfer radical polymerization (ATRP) and ring-opening polymerization (ROP), have been explored. Modification of surfaces and cellulose using these techniques, which enable grafting of well-defined polymer architectures, has been investigated. The interest in using cellulose stems from its renewability, biocompatibility, high molecular weight, and versatile functionalization possibilities. Dendronization was performed using disulfide-cored didendrons of 2,2-bis(methylol)propionic acid (bis-MPA) on gold surfaces, for the formation of self-assembled monolayers. It was found that the height of the monolayer increased with increasing dendron generation and that the end-group functionality controlled the wettability of the modified surface. Superhydrophobic cellulose surfaces could be obtained when a ‘graft-on-graft’ architecture was obtained using ATRP from filter paper after subsequent post-functionalized using a perfluorinated compound. The low wettability could be explained by a combination of a high surface roughness and the chemical composition. Biobased dendronized polymers were synthesized through the ‘attach to’ route employing dendronization of soluble cellulose, in the form of hydroxypropyl cellulose (HPC). The dendronized polymers were studied as nanosized objects using atomic force microscopy (AFM) and it was found that the dendron end-group functionality had a large effect on the molecular conformation on surfaces of spun cast molecules. ATRP of vinyl monomers was conducted from an initiator-functionalized HPC and an initiator-functionalized first generation dendron, which was attached to HPC. The produced comb polymers showed high molecular weight and their sizes could be estimated via AFM of spun cast molecules on mica and from dynamic light scattering in solution, to around 100-200 nm. The comb polymers formed isoporous membranes, exhibiting pores of a few micrometers, when drop cast from a volatile solvent in a humid environment. HPC was also used to initiate ROP of ε-caprolactone, which was chain extended using ATRP to achieve amphiphilic comb block copolymers. These polymers could be suspended in water, cross-linked and were able to solubilize a hydrophobic compound.QC 20100826
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Gonçalves, Maria Cecilia. "Estudo experimental da polimerização via radical livre controlada em presença de radicais nitroxido (NMRP)". [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266346.
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Orientador: Liliane Maria Ferrareso LonaDissertação (mestrado) - Universidade Estadual de Campinas. Faculdade de Engenharia Quimica
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Resumo: A polimerização via radical livre controlada mediante radicais nitróxido (NMRP) tem recebido cada vez mais atenção como uma técnica para produção de polímeros com estrutura altamente controlada. Distribuições de pesos moleculares estreitas são obtidas, com polidispersidades baixas. Neste trabalho, será estudado o processo NMRP, no qual ocorre a adição de um radical nitróxido estável, como o 2,2,6,6-tetrametil-l-piperidinoxil (TEMPO) para capturar o radical em crescimento. Embora o processo NMRP de ao polímero características controladas (polidipersidades baixas e pesos moleculares que aumentam linearmente com a conversão), ainda existe um desafio nos processos controlados, por apresentarem baixas velocidades de reação. O objetivo principal deste trabalho está focado num estudo experimental do processo NMRP visando aumentar a velocidade de reação sem perder as características principais do processo. O efeito de dois iniciadores BPO (peróxido de benzoíla) e TBEC (tert-butilperóxido-2-etilhexil carbonato) foi analisado. Observou-se que o TBEC (iniciador com constante de decomposição baixa) foi capaz de aumentar significativamente a taxa de polimerização do processo NMRP, quando comparado ao BPO, pois conversões mais altas foram obtidas, num mesmo tempo de reação, mantendo a característica controlada do sistema. O uso do TBEC apresenta uma vantagem frente ao BPO em processos controlados, não somente porque reduz o tempo de reação, mas também porque concentrações menores de iniciador e controlador foram usadas, obtendo uma taxa de reação ainda maior, o que reduz o custo operacional. Para as condições estudadas, comprovou-se experimentalmente que a taxa de reação é inversamente proporcional à concentração inicial de TEMPO, para uma mesma concentração de iniciador. A análise dos resultados através da aplicação da técnica de planejamento de experimento auxiliou numa melhor compreensão do sistema e na obtenção de condições ótimas de operação para se obter baixas polidispersidades e baixos tempos de polimerização
Abstract: NMRP process (Nitroxide Mediated Radical Polymerization) has received increasing attention as a technique for production polymers with highly controlled structures, narrow molecular weight distribution (MWD) and polydispersity index dose to 1.0. In this work 2,2,6,6-tetramethyl-l-piperidinoxyl (TEMPO) is used as the stable radical to reversibly terminate the growing polymer chain. Polymerizations were performed in ampoules, using TBEC (tert-butylperoxy-2-ethylhexyl carbonate) and BPO (benzoyl peroxide) as initiators. With the purpose of enhancing the reaction rate for NMRP process maintaining the controlled and living characteristics of the polymer synthesized (low polidispersity and molecular weights increasing linearly with conversion) an experimental study was done to evaluate the effect of two different initiators (BPO and TBEC). It was observed that TBEC (initiator with low decomposition rate) was able to enhance significant1y the polymerization rate compared to BPO, keeping the living and controlled characteristics of the system. The results show that TBEC seems to be a promising initiator that make the NMRP process more efficient, not only because it reduces the polymerization time, but also because it allows smaller amounts of controller and initiator to be used. For the operational conditions studied, experimental results with TBEC exposed that the polymerization rate in inversely proportional to the initial concentration of TEMPO, for the same amount of initiator. Using a statistical planning, it was possible to obtain a better understanding of the system and to search for operating conditions that bring low polydispersity and low reaction rates. Finally, the results are expected to have significant benefits for controlled polymerization on an industrial setting
Mestrado
Desenvolvimento de Processos Químicos
Mestre em Engenharia Química