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Reactivity ratios for the homogeneous free radical initiated copolymerization of acrylonitrile and methyl acrylate were measured by NMR on isolated, low conversion copolymers and by real time in situ FTIR. The system utilized azobisisobutyronitrile (AIBN) initiator in dimethyl formamide (DMF) at 62°. The FTIR technique allowed rapid generation of extensive copolymer compositions, which permitted application of nonlinear least squares methodology for the first time to this copolymer system. Thus, reactivity ratios at the 95% confidence level were determined to be 1.29 ± 0.2 and 0.96 ± 0.2 for acrylonitrile and methyl acrylate, respectively. The results are useful for the development of acrylonitrile (<90%) melt processable copolymer fibers and films, which could include precursors for carbon fibers. / Master of Science

High molecular weight star-shaped polystyrenes were prepared via the coupling of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) terminated polystyrene oligomers with divinylbenzene (DVB) in m-xylene at 138 °C. Linear polystyrene oligomers (Mn = 19,300 g/mol, Mw/Mn = 1.10) were synthesized in bulk styrene using benzoyl peroxide in the presence of TEMPO at approximately 130 °C. In situ mid-infrared spectroscopy was successfully utilized to follow initiation, monomer conversion, and polymer formation. Real-time data allowed for the determination of apparent rate constants of 2.1E-5 s⁻¹ at 132 °C and 1.2E-5 s⁻¹ at 126 °C from the profile of the decaying styrene vinyl carbon-hydrogen (=CH₂) absorbance at 907 cm⁻¹. Coupling of the TEMPO terminated oligomers under optimum conditions resulted in a compact and dense product with a number average molecular weight exceeding 300,000 g/mol (Mw/Mn = 3.03) after 24 h, suggesting the formation of relatively well-defined star-shaped polymers. Synthetic factors that affected the molecular weight, yield, and composition of maleic anhydride (MAH), norbornene (Nb), and tert-butyl 5-norbornene-2-carboxylate (NbTBE) terpolymers were investigated. Pseudo first order kinetic analysis using in situ FTIR indicated that the observed rate of reaction was a strong function of the Nb/NbTBE ratio with a maximum of 6.7E-5 s⁻¹ for a 50/0/50 Nb/NbTBE/MAH monomer ratio and a minimum of 1.1E-5 s⁻¹ for a 0/50/50 Nb/NbTBE/MAH ratio. Polymer yields were also observed to be a function of the Nb/NbTBE ratio and also decreased with increasing NbTBE. Calculated work of adhesion values (Wadh) values were observed to increase as the content of NbTBE was increased. 193 nm photoresist formulations incorporating polymers with high NbTBE content showed increased imaging performance using 193 nm light and successfully produced sharp and defined features as small as 110 nm, which was demonstrated via scanning electron microscopy (SEM). Additional functionality was introduced via the copolymerization of MAH with several norbornene (Nb) derivatives that were synthesized from facile Diels-Alder cycloaddition reactions of cyclopentadiene with a-olefins containing electron withdrawing groups. Subsequent hydrolysis of the anhydride offered further versatility and provided an avenue to introduce aqueous base solubility into Nb/MAH copolymers. / Ph. D.

The stable free radical polymerization methodology for production of controlled macromolecules was investigated using a novel monomer, 2-vinylnaphthalene. Initial polymerizations resulted in molecular weight distributions typical of conventional free radical polymerization techniques (>2.0). Manipulation of the initiator concentration and the molar ratio of initiator to nitroxide demonstrated no significant control over the resulting polymer products. Analysis of the polymerization kinetics for a 2-vinylnaphthalene polymerization performed in the presence and absence of the free radical initiator revealed identical monomer consumption profiles as well as pseudo first order kinetics indicating a significant degree of the thermal polymerization was occurring at the polymerization temperature (130°C). Comparison of the thermal polymerization propensity of 2-vinylnaphthalene and styrene revealed an increased tendency for 2-vinylnapthahlene to undergo thermal polymerization. Styrene is considered highly active in its propensity to thermally polymerize. However, an Arhenius analysis using in situ FTIR was employed to determine the activation energy for the thermal polymerization of styrene and 2-vinylnaphthalene. The 2-vinylnaphthalene activation energy for thermal polymerization was determined for the first time to be almost 30 kJ/mol less than styrene. A novel modified Mayo mechanism was proposed for the 2-vinylnaphthalene thermal initiation mechanism. Moreover, this thermal initiation was employed to initiate nitroxide mediated polymerizations of styrene. This first use of a 2-vinylnaphthalene initiating system resulted in polystyrene with a large macrocyclic initiating fragment. The presence of the initiating moiety was studied using both UV-Vis spectroscopy and 1H NMR spectroscopy. The extension of stable free radical polymerization to the acrylate monomer family was examined using a novel nitroxide mediator, N-tert-butyl-N-[1-diethylphosphono-(2,2-dimethylpropyl)] nitroxide (DEPN). The synthesis of DEPN was monitored using in situ FTIR spectroscopy to determine optimum reaction conditions. The purified nitroxide was subsequently employed in the synthesis of various block and random acrylate copolymers. The production of a unique amphiphilic block copolymer consisting of acrylic sequences was achieved. Poly(t-butyl acrylate-b-2ethylhexyl acrylate-b-t-butyl acrylate) was synthesized using the SFRP process. The t-butyl functionalities were subsequently removed in a post-polymerization acid catalyzed hydrolysis. The effect of steric bulk and electronic factors on the resulting SFRP process was also investigated and revealed similar polymerization kinetics for various alkyl acrylates. However, addition of a hydroxyl containing monomer, 2-hydroxyethyl acrylate, resulted in an increase in the polymerization rate up to 2 times. The rate enhancement was attributed to hydrogen bonding effects and this was confirmed using the unprecedented addition of dodecanol, which also demonstrated a significant rate enhancement. Block copolymers were also achieved using a novel difunctional nitroxide synthesized from 4-hydroxy TEMPO and 1,6-hexamethylene diisocyanate. The identity of the nitroxide was confirmed using mass spectrometry and 1H NMR. The dinitroxide was used in the polymerization of styrene and subsequently used to produce symmetric ABA triblock copolymers with t-butyl styrene using a unique two-step polymerization route. In addition, the dinitroxide demonstrated an increased tendency for decomposition due to the complex mediation equilibrium. The decomposition was studied using GPC to evaluate the decomposition effects on the polymerization. Results of the research efforts presented herein are written as individual research reports with contributing authors and pertinent literature reviews presented at the beginning of each chapter. / Ph. D.

Bien que thermodynamiquement et cinétiquement stable, le dioxyde de carbone est une molécule qui peut être convertie en carbonates cycliques à cinq ou six atomes respectivement au départ d’époxydes ou d’oxétanes moyennant l’utilisation d’un catalyseur approprié. Ces carbonates cycliques sont utilisés comme solvants verts, électrolytes pour les batteries au lithium ou comme intermédiaires pour la synthèse de polymères. Cependant, les performances catalytiques doivent être améliorées en particulier pour lecouplage du CO2 avec les huiles végétales époxydées ou les oxétanes. Dans ce contexte, nous avons développé un nouveau catalyseur homogène bicomposant organique composé d’un sel d’ammonium jouant le rôle de catalyseur et d’un co-catalyseur fluoré simple ou double donneur de liaison hydrogène. Dans un premier temps, l’efficacité de ces nouveaux catalyseurs a été évaluée et optimisée pour le couplage entre un époxyde terminal et le CO2 via des études cinétiques par spectroscopie FTIR ou Raman in-situ sous pression. Ces études ont démontré que l’utilisation combinée de sels d’ammonium et d’alcools fluorés induit un effet synergique permettant la fixation rapide et sélective du CO2 sur les époxydes modèles et les huiles végétales époxydées dans des conditions douces et sans solvant. L’utilisation de cette plateforme catalytique performante a ensuite été exploitée pour la synthèse d’oligocarbonates hydroxyles téléchéliques au départ d’oxétanes nettement moins réactifs que les époxydes. Ces oligocarbonates ont finalement été valorisés pour la synthèse de polyuréthanes CO2-sourcés par extension de chaines en présence de diisocyanates. En complément de ces travaux, une compréhension fine des mécanismes réactionnels a été réalisée via calculs DFT qui ont mis en évidence que l’efficacité catalytique de ces catalyseurs était liée à la stabilisation multiple des intermédiaires et états de transition par liaisons hydrogènes. A ce jour, via une étude comparative, nous avons mis en évidence que ce système catalytique bicomposant constitue un des catalyseurs organiques les plus performants pour le couplage du CO2 et d’époxydes et le seul système organique permettant la conversion d’oxétanes en synthons d’intérêt. / Although it is a thermodynamically and kinetically stable molecule, carbon dioxide can beconverted into five- and six-membered cyclic carbonates by coupling with epoxides or oxetanes, respectively, using appropriate catalysts. Cyclic carbonates are used as green solvents, electrolytes for Liion batteries or intermediates for the synthesis of polymers. However, the catalytic performance must be further enhanced in particular for the coupling of CO2 with epoxidized vegetable oils or oxetanes. In this context, we developed a new highly efficient bicomponent homogeneous organocatalyst composed of anammonium salt as the catalyst and fluorinated single or double hydrogen bond donors as co-catalysts. First,a screening of onium-based catalysts and hydrogen-bond donors was performed. Performances of thecatalysts and optimization of the reaction was realized through detailed kinetics studies using in-situ FTIR/Raman spectroscopy under pressure. We demonstrated that fluorinated alcohols showed unexpected co-catalytic activity due to synergisms between the onium salt and fluorinated co-catalysts enabling the fast and selective addition of CO2 on to model epoxides and epoxidized vegetable oils under solvent-free and mild experimental conditions. The use of this powerful dual catalyst was then extended to the first organocatalytic coupling of CO2 with less reactive oxetanes to produce hydroxyl telechelic oligocarbonates that were used asprecursor of CO2-based polyurethanes by chain-extension with a diisocyanate. In addition, a fine comprehension of the mechanisms was investigated by DFT calculations highlighting that the co-catalytic performance of the onium salt/fluorinated alcohol binary catalyst arose from the strong stabilization of the intermediates and transitions states by hydrogen-bonding. To date, through comparative studies, we evidenced that this new catalyst is one

Le procédé d’imprégnation par voie CO2 supercritique est une solution prometteuse pour préparer des implants polymère à libération contrôlée de médicaments.Ce travail a permis de comprendre l’influence des paramètres gouvernant ce procédé et de préciser dans quelle mesure ce procédé peut être utilisé pour préparer des implants polymères chargés en médicament. Pour ce faire, nous avons combiné les informations obtenues grâce aux techniques classiques de caractérisation de polymères et à un dispositif que nous avons développé basé sur la micro-spectroscopie FTIR haute pression in situ.Dans cette étude, des fils de suture de PLLA, PP and PET ont été imprégné avec deux anti-inflammatoires (aspirine et kétoprofène).Tout d’abord, l’évolution du comportement des systèmes binaires médicament/CO2 (solubilité et spéciation) et polymère/CO2 (quantité de CO2 adsorbé, gonflement de la matrice, évolution de la microstructure et des propriétés de tension du polymère) a été déterminé en fonction de la pression et de la température. Ensuite, le procédé d’imprégnation a été étudié. L’influence des conditions expérimentales sur le taux d’imprégnation a été déterminée et expliquée par la quantité de CO2 adsorbé, le gonflement de la matrice, la solubilité du médicament, l’évolution de la microstructure du polymère et aussi l’affinité médicament/polymère. La matrice de PLLA a pu être plus largement imprégnée (jusqu’à 32%) que celles de PP et PET (5% max). Enfin, l’influence des conditions d’imprégnation et de dépressurisation sur le relargage a été démontrée sur le système PLLA/Kétoprofène, la durée de relargage variant de 3jours à 3mois. / The scCO2 impregnation process is a promising alternative to other manufacturing process to prepare drug-eluting polymer implants.This work enabled to rationalize the influence of the key parameters governing this process and to determine in which extent this process can be used to prepare drug-eluting implants. We have combined the information obtained with traditional polymer characterization techniques and a newly characterization set-up we have developed that is based on in situ FTIR micro-spectroscopy. We have worked on the impregnation of sutures made of PLLA, PP and PET with two anti-inflammatory drugs namely ketoprofen and aspirin.Firstly, the thermodynamic behaviors of the systems drug/CO2 (solubility and speciation of the drug) and polymer/CO2 (CO2 sorption, polymer swelling, evolution of the polymer microstructure and of the tensile properties) were studied as a function of pressure and temperature. Then, the scCO2 impregnation process was investigated. The impact of the operational conditions on the drug loading (contact time, pressure, temperature and depressurization conditions) was explored and accounted regarding to the CO2 sorption, the2swelling, the drug solubility as well as the changes in the polymer microstructure with the experimental conditions and the presence of the drug. The drug/polymer affinity was also explored. The tensile properties of the impregnated fibers were also evaluated. PLLA was more impregnated (up to 32%) than PP and PET (up to 5%) in the investigated conditions. Finally, we have shown that the drug release can be tuned from 3 days to 3 months by varying the impregnation and depressurization conditions on the system PLLA/Ketoprofen.