Le confinement de polymères incompatibles au sein de particules induit une séparation de phase et conduit à la formation de morphologies particulières (cœur-écorce, hémisphérique…). Cette nanostructuration est à l’origine de propriétés de filmification particulières qui justifient l’utilisation des particules polymères composites dans le cadre d’applications comme la formulation de peintures ou de revêtements. Ce travail s’intéresse au développement d’approches permettant de préparer ces particules polymères composites en une seule étape et en milieu aqueux. La stratégie proposée repose sur le couplage « en simultané » de deux polymérisations distinctes: la polymérisation de cyclooléfines par métathèse (ROMP) et la polymérisation radicalaire par transfert d’atome (ATRP). Après avoir mis en évidence les difficultés liées au couplage de la ROMP et de l’ATRP en milieu dispersé aqueux, deux approches originales faisant intervenir respectivement des conditions de miniémulsion et de microémulsion sont proposées. Pour chacune d’elles, la présentation du principe de la synthèse et l’analyse de ses résultats précèdent l’étude morphologique des particules produites. / So as to broaden the scope of their applications in paints, coatings and impact-resistant plastics, many investigations have been dedicated to the preparation of nanostructured colloids over the past decades. Original morphologies including core-shell, hemispherical and complex occluded structures (raspberry-like, golf ball-like, octopus-like) can now be readily prepared. This work proposes a new straightforward one-pot, one-step, one-catalyst strategy to prepare polymer composite particles based on the simultaneous combination of two mechanistically distinct polymerizations in aqueous dispersed media. Norbornene (NB) and methyl methacrylate (MMA) were converted via Ring-Opening Metathesis Polymerization (ROMP) and Atom-Transfer Radical Polymerization (ATRP), respectively. Two original routes, designed to ensure simultaneous ROMP and ATRP, respectively under mini- and microemulsion conditions, are proposed. Both are successively reviewed on chemical and colloidal levels. Specific attention is paid to the morphologies of the prepared particles.

De nouveaux glycopolymères amphiphiles en peigne de type dextrane-g-poly(méthacrylate de méthyle) ont été obtenus via une polymérisation radicalaire contrôlée par transfert d’atome (ATRP). Pour contrôler les paramètres macromoléculaires de ces glycopolymères potentiellement biocompatibles et en partie biodégradables, la stratégie de synthèse « grafting from » a été sélectionnée et appliquée selon deux voies de synthèse. La première voie comporte quatre étapes : acétylation partielle des fonctions hydroxyle du dextrane ; introduction des groupements amorceurs d’ATRP ; ATRP contrôlée du méthacrylate de méthyle dans le diméthylsulfoxyde ; hydrolyse des groupements acétate dans des conditions douces. La seconde voie de synthèse permet d’obtenir ces glycopolymères en seulement deux étapes : introduction directe des groupements amorceurs d’ATRP sur le dextrane ; ATRP contrôlée du méthacrylate de méthyle dans le diméthylsulfoxyde. Des études détaillées de chaque étape ont permis à la fois d’estimer la longueur de la chaîne de dextrane et d’assurer le contrôle de l’architecture des glycopolymères (nombre et longueur des greffons). Des études préliminaires par tensiométrie interfaciale ont permit d’évaluer le caractère tensioactif de ces glycopolymères / Synthesis of the new comb-like amphiphilic glycopolymer dextran-g-poly(methyl methacrylate) was obtained thanks to an Atom Transfert Radical Polymerization (ATRP). In order to control the macromolecular parameters of these biocompatible and partly biodegradable glycopolymers, the “grafting from” strategy was applied using two different multi-step pathways. The first one is composed of four steps: partial acetylation of dextran hydroxyl groups; introduction of initiator groups convenient for ATRP; ATRP of methyl methacrylate in dimethylsulfoxide; acetyl group deprotection under mild conditions. The second pathway allows us to obtain such glycopolymers in only two steps: direct introduction of the same initiator groups onto the dextran chain and subsequent ATRP of methyl methacrylate in dimethylsulfoxide. Throughout the synthesis, detailed studies of each step enabled us to estimate the length of the dextran backbone and to assure the control of copolymer architecture in terms of graft number and graft length. Preliminary interfacial tension measurements highlighted the surfactant properties of such glycopolymers

Ces travaux de thèse ont consisté à développer de nouvelles réactions radicalaires dans le domaine de la glycochimie. Deux cascades radicalaires, n’utilisant aucun dérivé stannylé et impliquant un transfert d’hydrogène intramoléculaire, ont été étudiées. La première permet de synthétiser des motifs spirocétaliques [6.5] nonanomériques et la deuxième consiste à débenzyler régiosélectivement un éther de benzyle par proximité. Les spirocétals [6.5] nonanomériques sont des motifs présents dans de nombreuses structures de produits naturels. Pour obtenir ce squelette, dont la synthèse est généralement difficile, nous avons développé une cascade radicalaire en chaîne impliquant des précurseurs homopropargyliques et des dérivés phosphorés non toxiques. Plusieurs étapes se succèdent dont l’addition du radical phosphoré sur la triple liaison, un transfert 1,5 d’hydrogène permettant de générer un radical anomère de O-glycoside, à l’origine de la diastéréosélectivité du centre spiranique, et une cyclisation 5-exo-trig. Cette stratégie s’est révélée particulièrement efficace puisque de bons rendements et une excellente diastéréosélectivité ont été obtenus notamment en série glucose et glucosamine. La nouvelle réaction de O-débenzylation par proximité, développée dans la deuxième partie, permet de déprotéger sélectivement un éther de benzyle en α d’un groupement hydroxyle préalablement fonctionnalisé sous forme d’éther de silyle xanthate. Cette réaction se déroule en deux étapes successives dans le même ballon. La première est une cascade radicalaire constituée, entre autres, d’un transfert 1,7 d’hydrogène et de l’addition du radical benzylique, ainsi formé, sur le peroxyde de dilauroyle. L’acétal mixte intermédiaire obtenu est alors hydrolysé lors de la deuxième étape. Cette méthodologie a été appliquée avec succès à divers mono- et disaccharides polybenzylés et s’est révélée efficace en présence de nombreuses autres fonctionnalités chimiques (acétal de benzylidène, azido..). / The aim of this thesis was the development of new tin-free radical reactions in the field of glycochemistry. For this purpose, an intramolecular hydrogen atom transfer was the key step of these methodologies. The first reaction allowed the access to nonanomeric [6.5] spiroketals and the second one is a new regioselective de-O-benzylation reaction through proximity effect. The nonanomeric [6.5] spiroketals are widely distributed in natural products and have been difficult to access. To synthesize this scaffold, we have developed a chain radical cascade involving homopropargyl precursors and non-toxic phosphorus derivatives. The phosphorus-centered radical adds to the triple bond followed by a radical translocation through intramolecular hydrogen atom transfer. This key step of the reaction provides an intermediate O-glycoside anomeric radical, which ensure the diastereoselectivity of the reaction. Finally a 5-exo-trig cyclization yields the desired spiroketal. This strategy has been proved to be highly efficient since good yields and selectivity were obtained especially in glucose and glucosamine series. The new regioselective de-O-benzylation reaction through proximity effect, developed in the second part, allowed the deprotection of a benzyl ether in α position of a hydroxyl group previously functionalized as a xanthate silyl ether. This reaction occurs in two successive steps in the same flask. The first one is a radical cascade involving an 1,7 intramolecular hydrogen atom transfer and the addition of the newly formed benzylic radical on dilauroyl peroxide. The mixed ketal intermediate thus obtained is then hydrolyzed during the second step. This methodology has been successfully applied to several polybenzylated mono- and disaccharides and tolerates the presence of various chemical functions (benzylidene ketal, azido...) showing its versatility.

<p>Quantum chemical calculations have been performed to investigate radical cation rearrangement, radical carbonylation, and homolytic substitution reactions of organic molecules.</p><p>The rearrangement of the bicyclopropylidiene radical cation to the tetramethyleneethane radical cation is predicted to proceed with stepwise disrotatory opening of the two rings. Each ring opening is found to be combined with a striking pyramidalization of a carbon atom in the central bond.</p><p>The isomerization of the norbornadiene radical cation to the cycloheptatriene radical cation (<b>CHT</b><b>.+</b>), initialized by opening of a bridgehead–methylene bond, is investigated. The most favorable path involves concerted rearrangement to the norcaradiene radical cation followed by ring opening to <b>CHT</b><b>.+</b>. The barrier of this channel is found to be significantly reduced upon substitution of the methylene group with C(CH₃)₂.</p><p>Stepwise mechanisms are predicted to be favored over concerted isomerization for the McLafferty rearrangement of the radical cations of butanal and 3-fluorobutanal. The barrier for the concerted rearrangement is found to be lowered by 17.2 kcal/mol upon substitution, a result which is rationalized by the calculated dipole moments and atomic charges.</p><p>Recent experiments showed that photoinitiated carbonylation of alkyl iodides with [¹¹C]carbon monoxide may be significantly enhanced by using small amounts of ketones that have nπ* character of their excited triplet state. DFT calculations show the feasibility of an atom transfer type mechanism, proposed to explain these observations. Moreover, the computational results rationalize the observed differences in yield when using various alcohol solvents.</p><p>Finally, following photolysis of methyliodide, recent electron spin resonance spectroscopy experiments demonstrated that the S_H2 reaction ^•CD₃ + SiD₃CH₃ → CD₃SiD₃ + ^•CH₃ proceeds with high selectivity over the energetically more favorable D abstraction. The role of geometrical effects, especially the formation of prereactive complexes between methylsilane and methyliodide is studied, and a plausible explanation for the experimentally observed paradox is presented.</p>

The introduction of a nanoscopic reinforcing phase to a polymer matrix offers great possibilities of obtaining improved properties, enabling applications outside the boundaries of traditional composites. The majority of the work in this thesis has been devoted to polymer/clay nanocomposites in coating applications, using the hydroxyl-functional hyperbranched polyester Boltorn® as matrix and montmorillonite clay as nanofiller. Nanocomposites with a high degree of exfoliation were readily prepared using the straightforward solution-intercalation method with water as solvent. Hard and scratch-resistant coatings with preserved flexibility and transparency were obtained, and acrylate functionalization of Boltorn® rendered a UV-curable system with similar property improvements. In order to elucidate the effect of the dendritic architecture on the exfoliation process, a comparative study on the hyperbranched polyester Boltorn® and a linear analogue of this polymer was performed. X-ray diffraction and transmission electron microscopy confirmed the superior efficiency of the hyperbranched polymer in the preparation of this type of nanocomposites. Additionally, an objective of this thesis was to investigate how cellulose nanofibers can be utilized in high performance polymer nanocomposites. A reactive cellulose “nanopaper” template was combined with a hydrophilic hyperbranched thermoset matrix, resulting in a unique nanocomposite with significantly enhanced properties. Moreover, in order to fully utilize the great potential of cellulose nanofibers as reinforcement in hydrophobic polymer matrices, the hydrophilic surface of cellulose needs to be modified in order to improve the compatibility. For this, a grafting-from approach was explored, using ring-opening polymerization of ε-caprolactone (CL) from microfibrillated cellulose (MFC), resulting in PCL-modified MFC. It was found that the hydrophobicity of the cellulose surfaces increased with longer graft lengths, and that polymer grafting rendered a smoother surface morphology. Subsequently, PCL-grafted MFC film/PCL film bilayer laminates were prepared in order to investigate the interfacial adhesion. Peel tests demonstrated a gradual increase in the interfacial adhesion with increasing graft lengths. / QC20100621

The goal of this work was to synthesize complex macromolecular architectures such as dendrimers and dendronized polymers, and evaluate the effect from the dendrons on the optical and material properties. The work presented in this doctoral thesis, Dendrimers and Dendronized Polymers - Synthesis and Characterization, is divided into one minor and one major part. The first part deals with the synthesis and characterization of two sets of dendritic porphyrins based on 2,2-bis(methylol)propionic acid (bis-MPA). The second part deals with the synthesis and characterization of dendronized poly(hydroxyl ethyl methacylate), dendronized poly(norbornene), and dendronized triblock copolymers, were the pendant dendrons are based on bis-MPA. Both free-base and zinc containing dendritic porphyrins was synthesized up to the fifth generation by employing iterative ester coupling utilizing the acetonide protected anhydride of bis-MPA as generic building block. First and second generation dendron bearing methacrylates based on 2-hydroxyethyl methacrylate were also synthesized by utilizing the acetonide protected anhydride of bis-MPA, and subsequently polymerized by atom transfer radical polymerization. By adopting a divergent “graft-to” approach starting from the first generation dendronized poly(hydroxyl ethyl methacrylate), well-defined dendronized polymers with acetonide, hydroxyl, acetate and hexadecyl surface functionality were obtained. By utilizing the same divergent iterative esterfication, first to fourth generation dendron functionalized norbornenes were synthesized. These monomers were polymerized by ring-opening metathesis polymerization, utilizing either Grubbs´ first or second generation catalyst. Acrylate functional first to fourth generation monomers were synthesized by the copper(I) catalyzed “click” coupling of azido functional dendrons and propargyl acrylate. The monomers were polymerized to dendronized triblock copolymers by reversible addition-fragmentation chain transfer polymerization, utilizing a difunctional poly(methyl methacrylate) as macro chain transfer agent. The bulk properties of the dendronized poly(hydroxyl ethyl methacrylate) and poly(norbornene) were investigated by dynamic rheological measurements and differential scanning calorimetry. It was found that all the acetonide functional bis-MPA based dendronized polymers had glass transitions temperatures in a similar range. The rheological behaviour showed that for the dendronized polymers having the same backbone length the complex viscosity as a function of functionality was independent of the surface functionality of the polymer. The generation number of the polymer had a profound influence on the complex viscosity, changing form a Newtonian behaviour to a shear thinning behaviour when the generation of the dendrons was increased from two to four. The dendronized poly(norbornene) had increasingly shorter backbone lengths for each generational increase, and for the materials set with comparably lower degree of polymerization, the G’ part of the complex modulus was mostly affected by attaching larger dendrons. In the case of the sample set of higher degree of polymerization, the second, third, and fourth generation samples had similar slopes of the G’ and G” curves, indicating a similar relaxation behaviour. / QC 20100914

New water soluble, attainable to ATRP polymerization Cl-terminated poly(glycidol) macroinitiators were prepared by modification of (Omega)-hydroxyl group of poly(glycidol acetal) using 2-chloropropionyl chloride fallowed by selective acidic deprotection of acetal groups. The obtained macroinitiators of different molar masses were successfully employed in ATRP of NIPAM and 4VP to give well-defined stimuli sensitive block copolymers of targeted molar ratio of blocks. The results obtained from light scattering methods showed formation of stable aggregates upon stimuli (pH or temperature) by all the obtained polymers. Additionally, photocrosslinkable block copolymers of glycidol and NIPAM having incorporated moieties of chromophore (2-(dimethyl maleinimido)-N-ethyl-acryl amide) were prepared using macroinitiator technique and used to synthesis of temperature sensitive microgels. Conjunction points have been successfully formed by UV irradiation of polymer water solution above cloud point. The influence of such parameters like block ratio, block length, amount of chromophore, concentration, irradiation time, temperature and heating rate on the properties of obtained microgels was investigated. The obtained core-shell structures were stable under critical conditions and showed continuous volume phase separation process upon increase of temperature, fully reversible and reproducible (no hysteresis effect). Thus, the proposed method not only gave the opportunity to control size or swelling degree of microgels, but also diminished gradient in crosslinking density (random chromophore distribution in polymer backbone), improved colloid stability (poly(glycidol) shell) and completely eliminated additives (surfactants, initiators, stabilizers).

No description available.

Quantum chemical calculations have been performed to investigate radical cation rearrangement, radical carbonylation, and homolytic substitution reactions of organic molecules. The rearrangement of the bicyclopropylidiene radical cation to the tetramethyleneethane radical cation is predicted to proceed with stepwise disrotatory opening of the two rings. Each ring opening is found to be combined with a striking pyramidalization of a carbon atom in the central bond. The isomerization of the norbornadiene radical cation to the cycloheptatriene radical cation (CHT.+), initialized by opening of a bridgehead–methylene bond, is investigated. The most favorable path involves concerted rearrangement to the norcaradiene radical cation followed by ring opening to CHT.+. The barrier of this channel is found to be significantly reduced upon substitution of the methylene group with C(CH3)2. Stepwise mechanisms are predicted to be favored over concerted isomerization for the McLafferty rearrangement of the radical cations of butanal and 3-fluorobutanal. The barrier for the concerted rearrangement is found to be lowered by 17.2 kcal/mol upon substitution, a result which is rationalized by the calculated dipole moments and atomic charges. Recent experiments showed that photoinitiated carbonylation of alkyl iodides with [11C]carbon monoxide may be significantly enhanced by using small amounts of ketones that have nπ* character of their excited triplet state. DFT calculations show the feasibility of an atom transfer type mechanism, proposed to explain these observations. Moreover, the computational results rationalize the observed differences in yield when using various alcohol solvents. Finally, following photolysis of methyliodide, recent electron spin resonance spectroscopy experiments demonstrated that the SH2 reaction •CD3 + SiD3CH3 → CD3SiD3 + •CH3 proceeds with high selectivity over the energetically more favorable D abstraction. The role of geometrical effects, especially the formation of prereactive complexes between methylsilane and methyliodide is studied, and a plausible explanation for the experimentally observed paradox is presented.

No description available.