Ces travaux de recherche s'inscrivent dans le développement de nouveaux catalyseurs pour les piles à combustible de type PEMFC. L'objectif est d'améliorer le transfert de charges et de matières au sein des électrodes afin d'améliorer la durabilité des matériaux. Nous avons développé des catalyseurs qui permettent la transposition de la phénoménologie du point triple à l'échelle moléculaire. Le greffage de polymères conducteurs protoniques à la surface de nanoparticules de platine a été réalisé afin d'obtenir des complexes catalytiques nano-composites, comportant le catalyseur au platine, un conducteur protonique et un conducteur électronique. L'ensemble des matériaux issus de cette première étape ont été caractérisé en demi-cellule électrochimique afin de déterminer les catalyseurs les plus actifs et les plus sélectifs. Les matériaux les plus prometteurs ont enfin été testés en mono-cellule PEMFC de 5 cm² et 25 cm² afin de déterminer d'une part les performances in situ et d'autre part la durabilité des matériaux. Les électrodes nano-composites, formulées sans Nafion®, ont des caractéristiques équivalentes aux systèmes commerciaux. En effet, elles fournissent une densité de puissance maximale de 1 W.cm-2 et une durabilité de 20 µV.h-1 sur 300 h. Ces électrodes formulées sans composé fluoré permettent le recyclage du platine par pyrolyse. / This research work is within the scope of new catalysts for PEM fuel cells. The objective is to decrease the platinum amount in the electrode and to promote mass and electronic transfers, in order to improve the durability of the systems. We developed catalysts that enable the implementation of the phenomenology of the triple phase boundary at the molecular scale. The fieldwork concerns the grafting of proton conducting polymers (PSS) on the platinum nanoparticles surface in order to obtain nanocomposite catalysts. All synthetized materials are characterized in electrochemical half-cell, in order to determine the most active and the most selective catalyst. Then, the best catalytic complexes are tested in PEMFC 5 cm² and 25 cm² single-cell to determine in situ performance and materials durability. The properties of the nanocomposites electrodes formulated without Nafion®, are equivalent to commercial systems. Indeed, they provide a maximum power density of 1 W.cm-2 and a durability of 20 µV.h-1 during 300 h. These electrodes formulated without fluorinated compound allow platinum recycling by pyrolysis.

Miniaturization has become a driving force in different areas of technology including microelectronics, sensoric- and bio-technologies and in fundamental science. Because of the well-known limitations of conventional lithographic methods, newly emerging bottom-up approach, utilizing self-assembly of various nanoobjects including single polymer molecules and carbon nanotubes constitutes a very promising alternative for fabrication of ultimately small devices. Carbon nanotubes are attractive materials for nanotechnology and hold much promise to revolutionize fundamental science in a investigation of phenomena, associated with the nanometer–sized objects.It was found in this work that grafted chains of poly(2-vinylpyridine) form a shell covering the carbon nanotubes that makes them dispersible in organic solvents and in acidic water (CNTs-g-P2VP).The positively charged poly(2-vinylpyridine) shell is responsible for the selective deposition of carbon nanotubes onto oppositely charged surfaces. It was established that the deposition CNTs-g-P2VP from aqueous dispersions at low pH is an effective method to prepare ultra-thin films with a tunable density of carbon nanotubes.It was shown that poly(2-vinylpyridine) grafted to carbon nanotubes is a universal support for the immobilization of various nanoclusters at the carbon nanotube's surface. Prussian Blue nanoparticles were selectively attached to the surface of CNTs-g-P2VP.Conducting polymer nanowires are another very promising kind of nanomaterials that could be also suitable for applications in nanodevices and nanosensors. In this work was developed a simple method to control the conformation and orientation of single adsorbed polyelectrolyte molecules by co-deposition with octylamine. A simple chemical route to conductive polypyrrole nanowires by the grafting of polypyrrole from molecules of polystyrensulfonic acid was developed. The dc conductivity of individual polypyrrole nanowires approaches the conductivity of polypyrole in bulk.The conductivity can be described using variable-range hopping model.

La poly(2-isopropyl-2-oxazoline) (PIPOZ) est un polymère thermosensible qui possède une température de solution critique inférieure (LCST) autour de 40 °C en solution aqueuse. Les travaux présentés s’intéressent aux propriétés en solution aqueuse et aux interfaces, de l’homopolymère PIPOZ, d’une PIPOZ fonctionnalisée avec un groupement lipidique (lipo-PIPOZ) et de copolymères à blocs à base de poly(éthylène glycol) et de PIPOZ. Si elle est régulièrement comparée à son isomère structurel le poly(N-isopropylacrylamide) (PNIPAM), les études sur les propriétés en solution de la PIPOZ sont cependant moins complètes que celles sur le PNIPAM. Le premier objectif des travaux présentés ici est de parfaire la connaissance du comportement en solution de la PIPOZ en présence d’additifs. Les effets de sels et de solvants hydromiscibles sur la solubilité de la PIPOZ ont été investigués par turbidimétrie et microcalorimétrie sur trois homopolymères de masses moléculaires différentes. Contrairement aux solutions de PNIPAM, l’ajout de méthanol à la solution de PIPOZ ne conduit pas au phénomène de cononsolvency où la solubilité du polymère diminue pour une certaine gamme de fractions volumiques de cosolvant. L’effet a néanmoins été observé dans le cas de système PIPOZ/Eau/THF. L’effet de sels sur la solubilité de la PIPOZ suit la série Hofmeister. La présence de sels chaotropes (NaI et NaSCN) en solution ont révélé un effet bien plus important sur la solubilité de la PIPOZ que pour son isomère. Les valeurs de point troubles de la solution de PIPOZ augmentent de plus de 30 °C pour une concentration en sel supérieure à 1 M. L’autre objectif de cette thèse est de synthétiser un système à base de PIPOZ capable de s’auto-assembler à l’interface air-eau afin de former des films interfaciaux par la technique Langmuir-Blodgett. A cette fin, un amorceur contenant un groupement lipidique (2 chaînes alkyles et un groupement phosphate) a été synthétisé et utilisé pour la polymérisation cationique par ouverture de cycle (CROP) du monomère 2-isopropyl-2-oxazoline conduisant à l’obtention d’un lipo-PIPOZ (Mn = 10 kg.mol-1). L’effet de deux sels (NaSCN et NaCl) sur les films interfaciaux a été étudié. Malgré leur effet opposé sur la solubilité de la PIPOZ en solution, ils conduisent tous les deux à l’expansion de la monocouche de lipo-PIPOZ. Transférés sur des substrats de mica, ces films ont été visualisés par microscopie à force atomique (AFM). La iv présence de sels dans la sous-phase lors de la formation de monocouches conduit à la formation d’agrégats d’épaisseur ~ 10 nm dont le diamètre augmente avec la concentration en sel. Enfin, le dernier objectif est de caractériser les propriétés en solutions de copolymères à blocs PIPOZ-b-PEG-b-PIPOZ. La polymérisation par CROP de la 2-isopropyl-2-oxazoline a été amorcée à partir d’un PEG (Mn = 2 kg.mol-1) bifonctionnel, Le polymère synthétisé (TrOH, Mn = 11 kg.mol-1) a ensuite subit une fonctionnalisation des extrémités de chaînes par des groupements octadécyles conduisant à l’obtention d’un copolymère à blocs téléchélique amphiphile et thermosensible (TrC18). Les propriétés des copolymères en solution aqueuse ont été étudiées par turbidimétrie, diffusion dynamique de la lumière (DLS), microcalorimétrie (DSC), microscopie électronique à transmission et spectroscopie à sonde fluorescente, FT-IR et AFM. Les deux copolymères sont thermosensibles et présentent des valeurs de points troubles de ~ 48 °C pour le copolymère TrOH et de ~ 38 °C pour le copolymère amphiphile. Ce dernier s’auto-assemble à température ambiante et forme, en solution aqueuse, des micelles de type fleurs de rayon hydrodynamique RH ~ 8 nm. L’effet prolongé de la température sur la cristallisation des blocs de PIPOZ a aussi été examinée. Les deux polymères cristallisent en solution aqueuse conduisant à la formation de fibres insolubles dans l’eau. Mots- / Poly(2-isopropyl-2-oxazoline) (PIPOZ) is a thermosensitive polymer whose lower critical solution temperature (LCST) in water is ~ 40 °C. This thesis focuses on the properties in aqueous solution and on interfaces of new poly(2-isopropyl-2-oxazoline) systems. PIPOZ is often compared to its structural isomer, the renowned poly(N-isopropylacrylamide) (PNIPAM). If PNIPAM has been the center of thermosensitive polymer research for the last three decades, it is PIPOZ which has recently been gaining interest. The first aim of the thesis is to improve on the knowledge on PIPOZ properties in aqueous solution in the presence of water-soluble additives. Effect of salts and cosolvents were investigated by turbidimetry and microcalorimetry (DSC) on PIPOZ homopolymers of different molecular weights. Effect of salts on PIPOZ solubility follows the Hofmeister series. Chaotropic anions (SCN-, I-) induce a large increase (up to 30 °C) of the cloud point temperature of PIPOZ solution which is 10 times larger than for PNIPAM. Adding methanol into PNIPAM aqueous solution leads to a decrease in solubility of the polymer. This phenomena is called cononsolvency. Unlike PNIPAM solutions, the addition of methanol in PIPOZ solution does not lead to a cononsolvency effect. Nevertheless, cononsolvency has been observed in the case of THF addition into PIPOZ aqueous solutions. The second aim of this work was to design and synthesize an amphiphilic PIPOZ able to anchor itself at the air-water interface and to form stable monolayer via the Langmuir-Blodgett technique. For that purpose, a lipidic initiator containing two alkyl chains and a phosphate group, was synthesized and used to initiate the cationic ring opening polymerization (CROP) of 2-isopropyl-2-oxazoline. The obtained amphiphilic (lipo-PIPOZ, Mn = 10 kg.mol-1) forms stable monolayers at the air-water interface. The presence of salt (NaCl or NaSCN) in the sub-phase during the compression of the films leads to expansion of the monolayer even if the salts have opposite effect on PIPOZ solubility in solution. The interfacial films were then transferred onto mica substrates and captured by atomic force microscopy (AFM). The salts induced the formation of aggregates (height ~ 10 nm) whose diameter depends on the salt and its concentration. At last, a block copolymer, TrOH, containing a central poly(ethylene glycol) (PEG) (Mn = 2 kg.mol-1) and two PIPOZ blocks was obtained by CROP of 2-isopropyl-2-oxazoline initiated vi by a bi-functionnal PEG. The total molecular weight was Mn ~ 11 kg.mol-1. Hydrophobic chain ends modification has been performed onto TrOH to bring amphiphilicity and to get a telechelic octadecyl-end capped block copolymer TrC18. The properties of these two block copolymers in water were characterized by dynamic light scattering (DLS), microcalorimetry (DSC), electronic transmission microscopy (TEM) and fluorescence spectroscopy, FT-IR and AFM. Cloud point temperature of copolymer solutions was found to be around 48 °C for TrOH and around 38°C for the amphiphilic analogue TrC18. The latter self-assembles at room temperature into flower micelles whose hydrodynamic radius is RH ~ 8 nm. Extended heating of both copolymer solutions leads to crystallization of PIPOZ block and insoluble fibers form in solution.

Die Synthese von neuartigen organisch-anorganischen Polymer-Zeolith-Hybriden wird in der vorliegenden Arbeit vorgestellt. Die Hybride wurden durch kationische Polymerisation elek-tronenreicher Monomere direkt in den Poren der Zeolithe und zeolithanalogen Materialien hergestellt. Die Vinylether Ethyl-, Isobutyl-, Cyclohexyl- und 2-Chlor-ethylvinylether, 2,3-Dihydrofuran, 2-Methoxypropen sowie N-Vinylcarbazol wurden zur Herstellung der orga-nischen Komponente der Hybride genutzt. Die Polymerisation wurde dabei einerseits durch die Protonen der Zeolithgitter und andererseits durch separate Oberflächeninitiatoren gestar-tet. Die anorganische Basis der Hybride bildeten vorrangig mikroporöser HY-Zeolith und mesoporöses MCM-41. Bei der Synthese entstand neben dem eingeschlossenen Polymer im Zeolith eine vom Hybrid extrahier-bare Polymerfraktion. Beide Fraktionen wurden mittels GPC und einer speziellen Kopplung von GPC und UV/Vis-Spektrometer analysiert. DSC und dielektrische Spektro-skopie wurden zur Glasübergangstemperaturbestimmung herangezogen. Die Strukturuntersuchung der neuartigen Hybridmaterialien erfolgte mit Festkörper-NMR-Spektroskopie, Röntgendiffraktometrie XRD, Transmissionselektronenmikroskopie TEM, Sekun-därelektro-nenmikroskopie SEM, Elektronenstrahlmikroanalyse ESMA, UV/Vis-Spektroskopie und Infrarotspektroskopie FT-IR. Die Porentopologie wurde mit Stick-stoff-sorp-tionsmessungen bestimmt.

With the emergence of novel and more effective drug therapies, increased importance is being placed upon the methods by which these drugs are being delivered to the body. In conventional drug delivery systems, there is very little control over the release of drug. The effective concentration at the target site can be achieved by intermittent administration of grossly excessive doses, which, often results in constantly, unpredictable variations in plasma concentrations, with the risk of reaching levels below or above the therapeutic range leading to marked side effects. A plethora of formulation strategies mainly based on polymeric/lipid nanoparticles, are described in literature. Even though these systems are therapeutically advantageous in comparison to conventional systems, they remain insensitive to the changing metabolic states of the body although the symptoms of most metabolic diseases follow a rhythmic pattern.A more appropriate and effective approach of managing some of these conditions lies in the chronotherapy. This approach allows for pulsed or self-regulated drug delivery which is adjusted to the staging of biological rhythms, since the onset of certain diseases exhibits strong circadian temporal dependence. In order to reach the objective of mimicking the biophysical and biochemical processes of pathological states, many innovations in material design for drug delivery systems (DDS) that are able to release the therapeutic payload-on-demand were done to release the therapeutic agent only when it is required, according to the physiological need. The development of multidisciplinary research teams has brought huge advantages in the design, fabrication and utilization of such smart systems, especially in the pharmaceutical field. Interestingly, numerous smart polymeric materials exhibit a response to a specific stimulus. A step further, the elaboration of purpose-built monomers can give rise to compounds with tunable sensitivities or multi-stimuli responsiveness. These smart polymers demonstrate an active responsiveness to environmental (or external) signals and change their physicochemical properties as designed (e.g. conformation, solubility, shape, charge or size). As far as the stimuli are concerned, they consist of physical (e.g. temperature, ultrasound, light, electricity, magnetic or mechanical stress), chemical (e.g. pH, ionic strength) and biological signals (e.g. enzymes, biomolecules). Due to the intrapersonal variabilities which may make internal stimuli hazardous, externally controlled systems rely on externally applied stimuli that are produced by stimuli-generating devices, which results in pulsed drug delivery. This type of delivery may be rapid and allows a transient release of a determined amount of drug within a short period of time immediately after a pre-determined off-release period. A novel strategy for the formation of multi-stimuli responsive materials endowed with pH, magnetic and light sensitivity was achieved. The approach relied on the incorporation of magnetic tetrahalogenoferrate(III) anions along a polymeric backbone based on poly(2-(N,N-dimethylamino) ethyl meth-acrylate) (PDMAEMA). Starting from the same PDMAEMA, quaternized pending amine groups with various halide derivatives gave rise to magnetic materials after anion metathesis. Measuring the magnetic susceptibility of these materials exhibited that the magnetic susceptibility increased as the substituted group size decreased (become smaller) which was apparently related to the steric hindrance around the ionic pendants. Additionally, a good correlation between the magnetic susceptibility and ferric content was found. Additional experimental and theoretical Raman analyses allowed the determination of the nature of the magnetic species constituting the materials. This strategy further offers the opportunity to tailor the magnetic response through partial ammonium salt formation. In order to merge the magnetic properties of ferric-based materials with another stimuli-responsive functionality, random copolymers containing DMAEMA (D) with diazobenzene (A) unit were prepared. So, three copolymers PDA were synthesized (with targeted D/A ratios 4/6 (PDA4), 6/4 (PDA6) and 8/2 (PDA8)). Meanwhile, different degrees of amine quaternization (10, 50 and 100 %) were applied, which led to the following polymeric salts PDAX/Y where X = 4, 6, 8 (referring to the percentage of the DMAEMA unit) and Y = 10, 50 and 100 (referring to the percentage of quaternized amine groups). Finally, the aforementioned materials were converted into magnetic polymers by anion exchange. As a result, magnetic responses correlated well with amount of iron oxide in these compounds and the amount of ionic pending groups along the backbone. Moreover, the remaining tertiary amines conferred pH sensitivity to the polymers whereas the diazobenzene units ensured light responsiveness through the well-established trans-to-cis isomerization.In order to functionalize these materials in the pharmaceutical field, an intelligent delivery system was prepared. Firstly, an attempt to formulate riboflavin-5’-phosphate sodium (RPS) loaded on PDA8 microspheres was made using double emulsion evaporation method. Meanwhile, prednisolone (PRD) microspheres were prepared using s/o/w emulsion technique. Subsequently, coating systems of cochineal red tablets were developed. These tablets were coated with polymer solution (using each of three types of copolymers: PDA8, PDA6, and PDA4) until the desired percentage of the coating was achieved (10, 15, and 20 % w/w). The cumulative release profiles of cochineal red tablets coated with PDA8, PDA6, and PDA4 showed a pH-sensitive release behavior. The release in the neutral media (pH ≈ 7.0) was very slow (less than 3 % after one hour). Then, after changing the pH to 1.2, an increase in the release of cochineal was observed. Furthermore, the cumulative release of cochineal red was at the highest value for the PDA8 and the lowest for PDA4 depending on the percentage of PDMAEMA moieties. Moreover, by increasing the percentage of the coating from (10, 15 to 20 % w/w), the cumulative release of cochineal decreased. Therefore, the copolymer PDAX can be used for controlling the release of drug by changing the pH value.Finally, the cochineal tablets coated with PDA6 (10 %) showed features of light sensitivity. The release of cochineal red from coated tablets was only due to the switching in the conformational trans/cis isomerization of azobenzene moieties upon irradiation, which was confirmed by comparing the release of coated tablets with uncoated tablets upon irradiation. / Doctorat en Sciences biomédicales et pharmaceutiques (Pharmacie) / info:eu-repo/semantics/nonPublished

Os polímeros conjugados luminescentes são materiais com grande potencial tecnológico, mas apesar de estudados desde a década de 80, algumas de suas propriedades óticas ainda não foram totalmente entendidas. Por exemplo, ainda persistem dúvidas quanto à natureza das suas excitações primárias. Nesse sentido foi feito um estudo da fotoluminescência do poli[2-metoxy-5-(2-etil-hexiloxi)-1,4-fenileno vinileno] (MEH-PPV), polímero semicondutor luminescente cujas propriedades ópticas já foram muito investigadas. Além da banda de absorção principal na região visível do espectro, ele possui três bandas no ultravioleta. O objetivo deste trabalho é investigar a fotoluminescência do MEH-PPV quando excitado na região do ultravioleta. Após fotoexcitação no ultravioleta, observou-se apenas a fotoluminescência usual no visível. A intensidade da emissão depende fortemente da energia de excitação, da temperatura e da estrutura morfológica do sistema polimérico, determinada pelo método de preparação das amostras. Os resultados indicam que os estados excitados no ultravioleta relaxam rapidamente de forma não-radiativa até os estados de menor energia, de onde então ocorre a luminescência. Entretanto, a eficiência da fotoluminescência excitada no ultravioleta é consideravelmente reduzida, indicando que a excitação a altas energias abre novos canais de relaxação não-radiativos. / Luminescent semiconducting polymers are technological promising materials, but although studied since the 80’s some of their optical properties have not yet been fully understood. For instance, the nature of their primary excitations is still on debate. Therefore we proposed to study the photoluminescence following photoexcitation in the ultraviolet of the polymer poly(2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV). It is a semiconducting luminescent polymer with a main absorption band in the visible part of the spectrum, but with three other absorption bands in the ultraviolet. After ultraviolet photoexcitation it was observed only the usual visible photoluminescence. The intensity of photoluminescence depends strongly on temperature, excitation wavelength and morphological structure of the polymer, determined by the method of sample preparation. The results show that by ultraviolet excitation the excited states relax rapidly non-radiatively to the lower energy states, from where luminescence results. However, the photoluminescence efficiency with ultraviolet photoexcitation is considerably reduced, implying that the highly excited states in the polymer have more non-radiative relaxation channels available.

Os polímeros conjugados luminescentes são materiais com grande potencial tecnológico, mas apesar de estudados desde a década de 80, algumas de suas propriedades óticas ainda não foram totalmente entendidas. Por exemplo, ainda persistem dúvidas quanto à natureza das suas excitações primárias. Nesse sentido foi feito um estudo da fotoluminescência do poli[2-metoxy-5-(2-etil-hexiloxi)-1,4-fenileno vinileno] (MEH-PPV), polímero semicondutor luminescente cujas propriedades ópticas já foram muito investigadas. Além da banda de absorção principal na região visível do espectro, ele possui três bandas no ultravioleta. O objetivo deste trabalho é investigar a fotoluminescência do MEH-PPV quando excitado na região do ultravioleta. Após fotoexcitação no ultravioleta, observou-se apenas a fotoluminescência usual no visível. A intensidade da emissão depende fortemente da energia de excitação, da temperatura e da estrutura morfológica do sistema polimérico, determinada pelo método de preparação das amostras. Os resultados indicam que os estados excitados no ultravioleta relaxam rapidamente de forma não-radiativa até os estados de menor energia, de onde então ocorre a luminescência. Entretanto, a eficiência da fotoluminescência excitada no ultravioleta é consideravelmente reduzida, indicando que a excitação a altas energias abre novos canais de relaxação não-radiativos. / Luminescent semiconducting polymers are technological promising materials, but although studied since the 80’s some of their optical properties have not yet been fully understood. For instance, the nature of their primary excitations is still on debate. Therefore we proposed to study the photoluminescence following photoexcitation in the ultraviolet of the polymer poly(2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV). It is a semiconducting luminescent polymer with a main absorption band in the visible part of the spectrum, but with three other absorption bands in the ultraviolet. After ultraviolet photoexcitation it was observed only the usual visible photoluminescence. The intensity of photoluminescence depends strongly on temperature, excitation wavelength and morphological structure of the polymer, determined by the method of sample preparation. The results show that by ultraviolet excitation the excited states relax rapidly non-radiatively to the lower energy states, from where luminescence results. However, the photoluminescence efficiency with ultraviolet photoexcitation is considerably reduced, implying that the highly excited states in the polymer have more non-radiative relaxation channels available.

Die Synthese von neuartigen organisch-anorganischen Polymer-Zeolith-Hybriden wird in der vorliegenden Arbeit vorgestellt. Die Hybride wurden durch kationische Polymerisation elek-tronenreicher Monomere direkt in den Poren der Zeolithe und zeolithanalogen Materialien hergestellt. Die Vinylether Ethyl-, Isobutyl-, Cyclohexyl- und 2-Chlor-ethylvinylether, 2,3-Dihydrofuran, 2-Methoxypropen sowie N-Vinylcarbazol wurden zur Herstellung der orga-nischen Komponente der Hybride genutzt. Die Polymerisation wurde dabei einerseits durch die Protonen der Zeolithgitter und andererseits durch separate Oberflächeninitiatoren gestar-tet. Die anorganische Basis der Hybride bildeten vorrangig mikroporöser HY-Zeolith und mesoporöses MCM-41. Bei der Synthese entstand neben dem eingeschlossenen Polymer im Zeolith eine vom Hybrid extrahier-bare Polymerfraktion. Beide Fraktionen wurden mittels GPC und einer speziellen Kopplung von GPC und UV/Vis-Spektrometer analysiert. DSC und dielektrische Spektro-skopie wurden zur Glasübergangstemperaturbestimmung herangezogen. Die Strukturuntersuchung der neuartigen Hybridmaterialien erfolgte mit Festkörper-NMR-Spektroskopie, Röntgendiffraktometrie XRD, Transmissionselektronenmikroskopie TEM, Sekun-därelektro-nenmikroskopie SEM, Elektronenstrahlmikroanalyse ESMA, UV/Vis-Spektroskopie und Infrarotspektroskopie FT-IR. Die Porentopologie wurde mit Stick-stoff-sorp-tionsmessungen bestimmt.

This thesis focuses on the synthesis and characterization of various poly(arylene ether)s to improve the efficiency of gas separation and water desalination membranes. This class of polymers includes polymers such as poly(arylene ether sulfone), poly(arylene ether ketone) and poly(phenylene oxide) which offer excellent thermal and mechanical stability and usually have high enough rigidity to support gas separation and water desalination operations. Besides the plethora of properties offered by the homopolymers, these polymers can also be post-modified to cater to specific needs. For example, the polyphenylene oxides have been brominated to increase the permeability for gas separation applications. Blending is another viable method to impart desirable properties to polymers. Bisphenol A based poly(arylene ether ketone) (BPAPAEK) has been blended with commercially available poly(2,6-dimethylphenylene oxide)s (PPO) of different molecular weights in a fixed ratio (66/34 wt/wt) and in various ratios of a 22000 g/mol PPO. All the blends were UV crosslinked to minimize plasticization by condensable gases and analyzed for gel fractions, whereas, only the 22,000 g/mol blends were tested for transport properties since they yielded the highest gel fractions and exhibited the best mechanical properties. The crosslinking reduced the free volume and improved the selectivity with some drop in permeability. The blends with 90% of the 22000 g/mol PPO by weight was plotted closest to the upperbound. A phosphine oxide based poly(arylene ether ketone) (POPAEK) was blended with the various PPOs in a similar manner. The results were compared to the BPAPAEK based blends in terms of miscibility behavior and transport properties. It was found that the POPAEK based blends had higher permeability due to the higher fractional free volumes of the POPAEK. The POPAEK was more compatible with the PPOs than BPAPAEK as seen by analyzing various blend permeability models, mechanical properties and scanning electron microscope images. Moreover, blends with both the PAEKs displayed only a small drop in mechanical properties, such as the Young's modulus and the yield strength in comparison to the parent polymers. Hydroquinone based poly(arylene ether sulfone) oligomers were synthesized, post-sulfonated and chemically crosslinked to determine the effect of water uptake, fixed charge concentration and block length of oligomers on the salt permeability and the hydrated mechanical properties of the networks. The sulfonic acid groups were placed strategically and quantitatively on the hydroquinone units. The strategic placement of the acid groups may help in maintaining high rejection of monovalent ions in the presence of divalent ions, as shown in unpublished work by our group. It was found that the water uptake and fixed charge density had the opposite effects on the salt permeability. Also, the salt permeability varied differently for 5000g/mol and 10000g/mol block based networks. Another polymer that was investigated in this thesis was poly(2-ethyl-2-oxazoline) (PEtOx). An elaborate account of synthesis of monofunctional, heterobifunctional and telechelic poly(2-ethyl-2-oxazoline)s using different initiators including methyl triflate, activated alkyl halides (e.g., benzyl halides), and non-activated alkyl halides has been presented in this thesis. Endgroup functionalities and molecular weight distributions were studied by SEC, 1H NMR and titrations. The oligomers initiated with the benzyl or xylyl chloride had a PDI of 1.3-1.4 which is broader than expected for a living cationic ring opened polymer. This was attributed to the participation of covalent species which propagated slowly in the activated halide reactions. These oligomers were quantitatively terminated as proven by NMR and titrations. Due to the molecular weight distributions and quantitative termination these oligomers were deemed to be desirable for drug delivery applications. / PHD

Le traitement du cancer est l’un des plus grands défis en chimie médicinale moderne. La majorité des traitements utilisés repose sur la chimiothérapie, impliquant l’emploi de molécules bioactives cytotoxiques. Bien qu’efficaces, ces molécules présentent, pour la plupart, des désavantages notoires tels que le manque de spécificité cellulaire et une solubilité limitée en phase aqueuse. Une façon de remédier aux problèmes exposés est de solubiliser ces molécules au sein de matrices polymères. Il existe différents types de matrices qui sont : les liposomes, les micelles, les nanosphères, les nanocapsules, les dendrimères (et les polymères en étoile), et les polymères conjugués et linéaires. Dans cette thèse, nous faisons l’étude de deux matrices polymères potentielles composées de matériaux biocompatibles : le polylactide et la poly(2-isopropyl-2-oxazoline). La première partie de la thèse, est consacrée à l’étude des polyester-co-éthers portant des groupements pendants fonctionnalisables. Nous avons développé ces copolymères par polymérisation aléatoire en masse de lactones (le lactide ou la caprolactone) et différents taux d’éthers de propargyle et de glycidyle (GPE), à 120°C, en utilisant l’octanoate d’étain comme catalyseur. L’efficacité de la copolymérisation a été mise en évidence par des analyses FTIR, RMN 1H et COSY. Toutefois, L’analyse GPC a montré une diminution de la masse molaire des polymères et un élargissement de la dispersité en rapport avec l’augmentation du taux de glycidyle initial. De plus, les analyses RMN 1H ont montré que le taux de propargyl (provenant de l’éther de glycidyle) au sein du copolymère ne dépassait pas 50%. La faisabilité des modifications post-polymérisation a été évaluée en couplant le (9-azidomethyl) anthracène au chaîne de poly(ester-co-éther)s via la chimie clic CuAAC. Cette méthode s’est révélée inoffensive pour la chaîne de polyesters. Des études de cytotoxicité ont prouvé l’innocuité des poly(ester-co-éther)s. Des nanoparticules sphériques ont été préparées à partir de ces polymères et peuvent être utilisées comme nanosphères pour le transport de molécules bioactives hydrophobes. La copolymérisation des lactones avec des éthers de glycidyles s’avère être une stratégie intéressante de fonctionnalisation des chaînes des polyesters permettant la synthèse d’une large gamme de copolymères pour des applications biomédicales. Afin d’améliorer la synthèse des poly(ester-co-ether)s, nous avons proposé une approche mécanistique tenant compte des réactions de transfert de chaînes. Dans la deuxième partie de la thèse, nous avons étudié un polymère en étoile composé d’un polymère thermosensible : la poly(2-isopropyl-2-oxazoline) PIPOZ. Nous avons premièrement exploré deux approches synthétiques afin d’obtenir une série d’étoiles de PIPOZ (S-PIPOZ) de structure bien définié à savoir l’approche « coupling-onto » et l’approche « core-first ». Une première série de S-PIPOZ a été réalisée directement à partir d’un coeur pentaérythrityl tétratosylés par polymérisation cationique par ouverture de cycle (CROP) de 2-isopropyl-2-oxazoline pour l’approche « core-first ». Pour l’approche « coupling-onto », une deuxième série de S-PIPOZ a été réalisée par couplage via la CuAAC entre des PIPOZ-N3 linéaire (L-PIPOZ N3) et un cœur à 4 bras portant des alcynes terminaux. Tous les S-PIPOZs obtenus ont été analysés par RMN 1H, IR, MALLS-LS, des analyses UV et par microcalorimétrie différentielle à balayage (HS-DSC). Les polymères obtenus par l’approche « core-first » ont montré une microstructure mal-définie comparé à ceux obtenus par l’approche « coupling-onto ». Suite à ces résultats, nous avons défini l’approche « coupling-onto » comme voie d’obtention des S-PIPOZ. Une explication sur la structure mal-défini des polymères obtenus par l’approche « core-first » sera développée dans cette section. Nous exposerons aussi une méthode de purification permettant l’élimination rapide et efficace des L-PIPOZ N3 qui contaminent les échantillons de S-PIPOZ faits par l’approche « coupling-onto ». Cette méthode peut être applicable à d’autres polymères thermosensibles dans une certaine gamme de température. Dans la troisième partie, nous avons étudié l’effet de l’architecture et de la composition des bras-polymères sur la température de transition de phase et les propriétés des S-PIPOZs. Afin d’étoffer notre étude nous avons synthétisé un polymère en étoile à bloc composé de PIPOZ et de poly(éthylène glycol) PEG. Cette étude a été réalisée en examinant des solutions chauffées de polymères (S-PIPOZ, S-PIPOZ-b-PEG et tous les précurseurs linéaires) par des analyses de spectrométrie d’absorption UV, HS-DSC, diffusion de la lumière LS. Nous avons évalué la présence ou l’absence de cristaux au sein d’échantillons de S-PIPOZs provenant de solutions chauffées. Cette évaluation a été réalisée par diffusion des rayons-X aux grands angles (WAXS) et par microscopie électronique à transmission (TEM) et à balayage (SEM). La présence de cristaux est néfaste pour la conception de nanomatériaux destinés à des applications biomédicales. Nous exposons aussi dans cette section une méthode basée sur l’amination réductrice permettant de fonctionnaliser les S-PIPOZ avec différents types de macromolécules. Cette thèse expose les avantages et les inconvénients (synthèses, fonctionnalisation, structures…) des PLA-co-GPE et des S-PIPOZs et constitue dans son ensemble à une première ébauche vers une conception améliorée de futurs nanomatériaux. / Treatment of cancer is one of the biggest challenges in modern medicinal chemistry. The vast majority of treatments are based on chemotherapy, involving the use of cytotoxic bioactive molecules. Although effective, most of these bioactive molecules have notorious drawbacks, such as the lack of cellular specificity and limited solubility in aqueous media. A way to address these problems is to dissolve these bioactive compounds into polymer matrices. There are different types of matrices, including liposomes, micelles, nanospheres, nanocapsules, dendrimers (and star-polymers), and conjugate and linear polymers. In this thesis, we explored two different prospective polymers that can be used as matrices. Both are composed of biocompatible materials: polylactide and poly(2-isopropyl-2-oxazoline). The first part of the thesis is dedicated to the investigation of polyester-co-ether with functionalizable pendant groups. First, we developed the polyester-co-ether by copolymerization of lactones (lactide or caprolactone) with different ratios of glycidyl propargyl ether (GPE) in the bulk at 120°C in the presence of Sn(Oct)2. The efficiency of the copolymerization was evidenced by FTIR, 1H and COSY NMR analyses. However, GPC analyses displayed a decrease of molecular weights and a broadening of the molecular weight dispersity with increasing of the epoxide molar ratio in the feed. 1H NMR analyses showed that the propargyl content from the epoxide does not exceed 50%. The feasibility of post-polymerization functionalization was evaluated by coupling anthracene to the poly(ester-co-ether)s through copper-catalyzed alkyne-azide cycloaddition (CuAAC). The polyester chain was found to support this reaction. Toxicity studies showed that the poly(ester-co-ether) was non-toxic. Spherical nanoparticles were prepared from these polymers. They can be suitable nanospheres for drug delivery. The copolymerization of lactone with glycidyl ether is an interesting approach to functionalize the PLA (or poly(ester)) main chain. It is also a powerful and straightforward strategy to synthesize a large array of functionalized polymers for biomedical applications. In order to improve the synthesis of the polyester-co-ether, we investigated the copolymerization mechanism of the chain transfer reactions leading to the chain reductions and we suggested a mechanistic explanation. In the second part of this thesis, we focused on developing star-polymers from the thermosensitive (2-isopropyl-2-oxazoline) polymer. In order to prepare a well-defined set of star-poly(2-isopropyl-2oxazoline) S-PIPOZs, we explored two different synthetic approaches: the “coupling-onto” and the “core-first” approach. Two sets of S-PIPOZs were prepared by these approaches. For the “core-first” approach, a set of S-PIPOZ was prepared by direct cationic ring opening polymerization (CROP) from a tetra tosylate-functionnalized pentaerythrityl core. For the “coupling-onto approach”, the S-PIPOZs were prepared by ligation between L-PIPOZ-N3 and a 4-arm core with an alkyne group via CuAAC. The prepared polymers were analysed by 1H NMR, IR, Multi Angles Laser Light Scattering - Gel Permeation Chromatography (MALLS-GPC), UV absorption spectroscopy and High Sensitive Differential Scanning Microcalorimetry (HS-DSC). Polymers obtained by the “core-first” approach shows ill-defined microstructure compared to those obtained by the “coupling-onto” approach. In light of these encouraging results, the “coupling-onto” method was pursued for preparing S-PIPOZ. An explanation on the ill-defined structure will be provided within this thesis. Moreover, we developed a purification method for the fast and efficient removal of free PIPOZs, which otherwise contaminate the star-PIPOZ samples that are prepared by the coupling-onto approach. This method is applicable to other thermosensitive polymers within a certain range of temperature. In the third part, we focused on the effect of the architecture and composition of the S-PIPOZs on the phase transition temperature of the polymer. For this, we synthesized a hetero-star block copolymer composed of PIPOZ and poly(ethylene glycol) PEG. This study was carried out by examining the aqueous polymer solution (the linear precursors, S-PIPOZs, S-PIPOZ-b-PEG) upon heating via UV spectroscopy, HS-DSC and light scattering. We also assessed the temperature-induced crystallinity of the Star-PIPOZs by Transmission (TEM) and Scanning (SEM) Electron Microscopy, WAXS. This is important for biomedical nanodevices. We also provided a straightforward method, based on aminative reduction, to functionalize the S-PIPOZ with different macromolecules. This thesis discusses the advantages and the drawbacks related to the synthesis, functionalization, structures of PLA-co-GPE and the star-PIPOZs. Overall, this represents a pioneering study for improving the design of prospective nanodevices.