Dans le domaine des polymères, l'auto-organisation de la matière a été largement étudiée dans les dernières années et beaucoup de progrès dans le domaine des films ordonnés, générés par l'auto-assemblage de copolymères à blocs, ont été réalisés. Ce progrès est motivé par le fait que les films auto-assemblés possèdent des applications en biologie, photonique, adhésion. Le sujet initial de thèse est la fabrication des films structurés en nid d’abeilles formés par un bloc de copolymère contenant une partie hydrophobe ( à peu près 90%) et une partie hydrophile (10%) qui peuvent s’auto-organiser en nid d’abeilles. Les films de polymères préparés seront ultérieurement à la base d’une étude de complexation avec des métaux. Ceci sert à décontaminer les eaux usées des métaux ou pesticides. Durant ces années de thèse, une méthodologie d’analyse de surface est détaillée pour comprendre la topographie de ces films ainsi que la chimie de surface de ces derniers. Pour cette raison, divers techniques d’analyses sont utilisées pour décrire vigoureusement la surface de ces films afin d’optimiser ces films pour complexer les contaminants à origine industrielle.Une des techniques d’analyse de surface, i.e. TOF-SIMS (Time Of Flight-Secondary Ion Mass Spectroscopy), a prouvé être un outil efficace pour caractériser chimiquement la composition élémentaire et moléculaire de l’extrême surface et en profondeur. Cette technique était la technique de base de ces études. Elle la permis de décrire les empreintes spectrales ainsi que la distribution en surface et en profondeur de chaque polymère dans les films élaborés en nid d’abeilles. / Since its introduction in 1994, the preparation of ordered porous polymer films by the breath figure “BF” method has received a considerable interest. Self-organized porous polymer films, with pores ordered into a hexagonal pattern, can be elaborated by a fast solvent evaporation method under a humid atmosphere, also called “Breath Figure” approach. The honeycomb films have found a panel of perspective applications ranging from materials with optical properties, biomaterial sensors, and scaffold for tissue engineering or highly hydrophobic surfaces. The main objective of this PhD thesis project is the fabrication of sensitive hierarchically self-organized bio inspired films based on organic compound trapping block copolymers. It is worth noting that one of the advantages of using block copolymer structure is that the first block confers the hydrophobic character, required for the elaboration and stability of HC structure, and the second block could provide an additional functionality such as hydrophilicity, stimuli-responsive character or trapping of targeted molecules (especially metals).During this thesis, a methodology of surface analysis is performed in order to understand the topography of these films as well as its surface chemistry. For this reason, various analytical techniques are used to describe the surface of these films vigorously in order to optimize these films to complex industrial contaminants.One of the techniques of surface analysis, i.e. TOF-SIMS (Time of Flight-Secondary Ion Mass Spectroscopy), has proved to be an effective tool for chemical characterization of the surface and in depth. This technique was the basic technique of our studies. It allowed the description of spectral finger prints as well as the distribution on the surface and in depth of each polymer in the structured films.

Nous avons étudié la formation de micelles PIC de copolymères à blocs double-hydrophiles (DHBC) destinées à servir d’agents structurants pour l’élaboration de matériaux siliciques mésoporeux et fonctionnalisés. L’intérêt du mode d’assemblage par complexation de polyions (PIC) est qu’il est réversible. Les micelles se forment spontanément dans une gamme restreinte de pH et sont dissociées à l’issue de la condensation de la silice par simple changement du pH. La porosité du matériau est ainsi révélée par simple élution et non plus par calcination. Si une fraction contrôlée de l’agent structurant pouvait être préservée au sein du matériau final, il deviendrait possible de fonctionnaliser le matériau sans ajouter d’étapes supplémentaires à son procédé d’élaboration. Relever ce défi repose sur une maîtrise de la réversibilité de la formation des micelles PIC, de leur comportement lyotrope et sur la possibilité de former des micelles à couronne mixte à partir de DHBC qui diffèrent par la nature de leur séquence neutre.Au cours de ce travail, nous avons synthétisé plusieurs familles de DHBC par polymérisation radicalaire contrôlée RAFT et MADIX en phase aqueuse. La séquence polyélectrolytique des DHBC est constituée d’acide polyacrylique, tandis que la séquence neutre est constituée soit de polyacrylamide (PAM) soit de poly(oxyde d’éthylène) (POE). Les masses molaires visées ont été obtenues et sont associées une dispersité faible (RAFT) à modérée (MADIX), gage d’un bon contrôle des processus de polymérisation. Plusieurs homopolyélectrolytes cationiques, faibles et forts, ont été utilisés comme agents de micellisation (AM). Les constantes d’acidité, les taux de condensation des contre-ions et les mobilités électrophorétiques ont été déterminés, dans un premier temps, pour les polyélectrolytes dissouts séparément, puis dans les mélanges de polyélectrolytes de charge opposée, en condition de complexation. Les différences de constantes d’acidité reflètent la constante de complexation électrostatique, tandis que l’excès de conductivité des mélanges renseigne sur le nombre de sites ioniques qui participent à l’assemblage des macromolécules.Les micelles PIC sont constituées d’une dizaine à une centaine de DHBC et présentent une structure cœur-couronne de quelques nanomètres (5-15 nm). Une corrélation inverse entre la cohésion du complexe électrostatique et la taille des micelles est mise en évidence pour la première fois. Elle pourrait s’expliquer par une quantité d’eau au sein du coacervat complexe d’autant plus importante que les points d’ancrage entre macromolécules sont moins nombreux. Par ailleurs, le comportement lyotrope observé jusqu’à des fractions massiques de 60% ne présente aucune mésophase organisée. Enfin, si la formation de micelles mixtes dans les mélanges associant des DHBC de natures différentes semble avérée, la structuration interne de leur couronne, riche en POE vers le cœur et riche en PAM en périphérie, présenterait une ségrégation radiale qui n’est pas propice à une interaction forte du POE avec la silice et remet sans doute en cause l’utilisation de telles micelles mixtes comme agents structurants pour la synthèse de matériaux mésoporeux fonctionnalisés. Cependant, des alternatives sont envisageables. / Double-Hydrophilic Block Copolymer (DHBC) based PIC micelles were studied for their suitability as structuring agents for the synthesis of functionalized mesoporous silica materials. Assembling micelles through polyions complexation (PIC) is interesting because it is reversible and restricted to a limited range of pH when weak polyelectrolytes are used. Once silica condensation has proceeded, micelles can be disassembled by changing the pH. In this way, the porosity of the material is revealed by elution rather than calcination. If a controlled fraction of the structuring agent could be maintained within the final material, this would open the road to one pot synthesis of functionalized mesoporous materials. Addressing this challenge relies on a good control over the reversibility of the assembling process of the micelles, over their lyotropic behavior and on the possibility to form corona-mixed micelles from two DHBC carrying different neutral blocks.Several series of DHBC were synthetized by controlled radical polymerization in aqueous phase, either by RAFT for poly(ethylene oxide)-based DHBC, or by MADIX for polyacrylamide-based DHBC. The polyelectrolyte block is polyacrylic acid. The targeted molar masses were achieved and low (RAFT) to medium (MADIX) dispersity were obtained testifying a good control over the polymerization process. Various cationic homopolyelectrolytes, either weak or strong, were used as micellization agents (MA). Acidity constants, condensation ratios and electrophoretic mobilities were determined, first for each polyelectrolyte by its own, and then mixed with its MA in suitable conditions for micellization. Change of the apparent acidity constant reflects equilibrium constant of electrostatic complexation, while excess of conductivity reveals the number of ionic sites that are involved in the complexation of both macromolecules.PIC micelles are few nanometers large (4-15 nm) and gather from ten to one hundred DHBC molecules. They show the typical core-corona structure of polymer self-assemblies. An inverse correlation between the size and the cohesion of the complex is evidenced for the first time. It could be explained by the amount of water inside the micelle coacervate core that should increase when the number of anchoring sites between the oppositely charged macromolecules decreases. Up to a weight fraction of 60 wt% , the PIC micelles do not show any lyotropic mesophases. Finally, mixed PIC micelles certainly form when different DHBC are mixed with an MA, however, the corona looks richer in PEO the closer to the core and richer in PAM at the external rim. Such radial segregation of the corona block is not suitable to ensure enough interaction of PEO with silica and could preclude the use of such mixed micelles as structuring agent for the one pot synthesis of functionalized mesoporous materials. Alternatives are proposed.

O muco protege o corpo humano de partículas externas, mas também representa uma barreira para a entrega de controlada de medicamentos através de nanocarregadores. Para ultrapassar a barreira do muco e impedir mucoadesão, nanopartículas sólidas são normalmente revestidas com polímeros inertes, tais como o polietileno glicol (PEG). No entanto, trata-se de um procedimento relativamente complexa. Nesta tese, estudamos métodos para fabricar nanocarreadores com uma excepcional combinação de propriedades, incluindo uma boa capacidade de mucopenetração e uma grande capacidade de carga. Ao contrário dos métodos convencionais de revestimento, usamos um copolímero dibloco, que consiste em dois blocos hidrofóbicos e hidrofílicos, que se auto-organiza em polimerosomos sob hidratação. Devido à inércia do bloco hidrofílico, estes polimerosomos devem ser, por natureza, muco penetradores. Além disso, sua estrutura oca fornece os polimersomos para serem carregados com carga hidrofílica, enquanto a carga hidrofóbica pode ser transportada através da membrana. Por conta da utilização de um polímero hidrolisável na presença de ácido, ácido poli láctico (PLA) como a espinha dorsal copolímero, demonstramos que estes polimerosomos podem liberar o conteúdo, após aplicação do estímulos externo relacionado ao pH. Os experimentos de rastreamento de partículas demonstraram que os polimersomos se difundem mais rápido do que as partículas não revestidas, em muco de intestino de porco, e testes de biodistribuição apresentaram resultados encorajadores para a entrega localizada de fármacos de maneira mais homogênea, melhorando a biodisponibilidade e efeitos terapeuticos. Mais estudos relacionados ao aumento da eficiência de encapsulação e testes de efetividade in vivo no tratamento de doenças devem ser promovidos. Acreditarmos que combinação das vantagens relacionadas à estrutura vesicular dos polimerossomas, estabilidade, e muco penetração possibilitam o desenvolvimento de uma nova plataforma para a entrega controlada de medicamentos na mucosa. / Mucus protects the human body by trapping foreign particulates but also poses a barrier for drug delivery by slowing down the mobility of drug carriers. To design mucus penetrating carriers, solid particles are typically coated with inert polymers such as polyethylene glycol (PEG) to prevent mucoadhesion. However, the solid structure of these particles limits their loading capabilities and the process to coat them requires a complex synthesis. In this thesis we studied methods to fabricate nanocarriers with an exceptional combination of properties including a good mucus-penetration capability and loading capacity of hydrophilic and hydrophobic cargos. Unlike conventional coating methods, we use a diblock copolymer, consisting of both hydrophobic and hydrophilic blocks, which self-assembles into polymersomes under hydration. Because of the inertness of the hydrophilic block, these polymersomes should be mucus-penetrating by nature. Moreover, their hollow structure provides the polymersomes to be loaded with hydrophilic cargo, whereas hydrophobic cargo can be carried through the membrane. Importantly, by using a hydrolysable acid-catalyzed polymer (poly lactic acid, PLA) as the copolymer backbone, we demonstrate that these polymersomes can release contents upon application of external pH stimuli. Particle Tracking experiments demonstrated that polymersomes diffuse faster than uncoated particles in porcine intestine mucus, and biodistribution tests displayed encouraging results towards more homogeneous local drug-delivery, helping bioavailability as well as therapeutic efects. More studies related to the increase of encapsulation efficiency, and in vivo disease treatment tests should be promoted. Although we believe that combining the advantages of polymersome carrier, and tunning the membrane composition, this mucus-penetrating carrier we propose may provide as a new platform for mucosal drug delivery.

Les propriétés des matériaux découlent en partie de leur organisation à l’échelle nano ou microscopique. Dans cette thèse, on montre qu’en contrôlant la chimie aux interfaces, des organisations très régulières peuvent être obtenus spontanément dans divers matériaux polymères.Dans une première, la chimie supramoléculaire a été utilisée pour contrôler l’organisation en masse de polymères greffés à une ou deux de leurs extrémités par la thymine (Thy) ou la 2,6-diamino-1,3,5-triazine (DAT), deux unités supramoléculaires complémentaires s’associant par liaisons hydrogène. Quelque soit la nature de la chaine polymère (PE, PDMS, PPG), les matériaux présentent des organisations lamellaires nanoscopiques très régulières lorsque l’unité terminale (Thy) et/ou la chaine (PE) cristallisent. Les contributions respectives à ces organisations de la ségrégation de phase, de la cristallisation, des liaisons supramoléculaires et des interactions secondaires ont été déterminées. Il a été montré que le confinement des chaines polymères dans les lamelles empêche la formation de chaines de grandes masses molaires. Cependant, les interactions supramoléculaires Thy/DAT permettent de former des copolymères à blocs supramoléculaires en mélangeant des chaines incompatibles fonctionnalisées par ces unités.Dans une seconde partie, nous avons montré que la texturation spontanée de films acrylates photopolymérisés à l’air est gouvernée à l’interface formulation/air par l’équilibre des cinétiques de polymérisation et d’inhibition par l’oxygène. Des morphologies microscopiques très régulières, hexagonales, lamellaires ou cacahuètes, sont obtenues en contrôlant différents paramètres expérimentaux et ce pour une large gamme d’épaisseur de film (6 µm – 2 mm). L’auto-texturation confère aux films des propriétés optiques singulières (flou, clarté) qui peuvent être modulées en ajustant les caractéristiques de la morphologie. / Materials properties very often derive from their nano or micro-scale organization. In this thesis, we evidence that controlling the chemistry at the interfaces allows obtaining spontaneously very regular organizations in various polymer materials.In the first part, supramolecular chemistry has been used to control the organization in the bulk of polymer grafted at one or both extremities by thymine (Thy) or 2,6-diamino-1,3,5-triazine (DAT), two self-complementary supramolecular units interacting via hydrogen bonds. Whatever the polymer nature (PE, PDMS, PPG), materials present very regular nanoscale long-range ordered lamellar organizations if the end group crystallize (Thy) and/or the chain crystallize (PE). Respective contributions to these organizations of phase segregation, crystallization, supramolecular interactions and secondary interactions have been determined. It was shown that the confinement of chains in lamellae prevent the formation of high molecular weight chains, resulting in poor mechanical properties. However, Thy/DAT interactions allow creating supramolecular block copolymers by mixing incompatible chains functionalized with these units.In the second part, we have studied the spontaneous formation of patterns at the film surface of acrylate film during their photopolymerization under air. This phenomenon occurs if there is a balance at the film surface between the polymerization and the oxygen inhibition rates. Very regular microscale patterns (hexagons, lamellae, peanuts) have been generated by controlling some experimental parameters (UV intensity, initiator concentration) for a wide range of film thicknesses (6 µm – 2 mm). Self-patterning gives interesting optical properties to the films (haze, clarity) which can be modulated by adjusting the patterns wavelength and amplitude.

Fullerenhaltige Bulk-Heterojunction-Solarzellen auf Polymerbasis zeigen derzeit eine geringe Langzeitstabilität, die unter anderem auf der Entmischung der Bulkphasen beruht. In dieser Arbeit wurden daher auf neuartige Weise Blockcopolymere entwickelt, die zur Stabilisierung der Phasen dienen können. Ausgehend von Poly-3-hexylthiophen-Makroinitiatoren wurde ein zweiter Block mit reaktivem Comonomer polymerisiert, das zur Anbindung von reinem Fullerens bzw. von Fullerenderivaten diente. Die fullerenfunktionalisierten Polymere wurden in Modell-Systeme eingemischt und zeigten erste Verbesserungen bezüglich der Phasenstabilisierung.

As an inspiration from nature, polymeric vesicles can be formed from amphiphilic block-copolymers. These vesicles are called polymersomes and have applications in drug delivery and as nanoreactors. Within this thesis, photo cross-linked and pH sensitive polymersomes were synthesized, characterized and applied on cells as well as bionanoreactors. The stability due to the crosslinking yielded polymersomes which show a distinct and reproducible swelling upon repeated pH changes. If the non cross-linked vesicles were exposed to a plasma-cleaned surface, they formed a tethered singly and multiple bilayers. Upon studying these membranes, they turned out to harden upon crosslinking and showed a completely non-fluid behaviour. Additionaly, the polymersome-cell interactions were studied and yielded a high influence of the crosslinking conditions on cellular toxicity. If crosslinked for a long time in a phosphate-free enviroment, the polymersomes proved to be least toxic. Finally, an enzyme was incorporated into the polymersomes to create bionanoreactors. Due to the pH sensitivity and swelling, the vesicles created yielded a pH controlled nanoreactor with enzymatic activity and a swollen, e.g. acidic, state only.

This thesis described the development of new strategies for the preparation of micro- and nano-structured polymer materials. In particular, this thesis focused on: i) the synthesis of polymer particles in microreactors, and ii) the self-assembly of inorganic nanorods. First, this thesis presented the synthesis of polymer particles and capsules with pre-determined sizes and narrow size distributions (CV<2%) in continuous microfluidic reactors. The method includes (i) the emulsification of monomers in a microfluidic flow-focusing device and (ii) in-situ solidification of droplets via photopolymerization. This microfluidic synthesis provides a novel strategy for the control over the shapes, compositions, and morphologies of polymer particles. In particular, we demonstrated the control over particle shapes by producing polymer ellipsoids, disks, rods, hemispheres, plates, and bowls. We produced polymer particles loaded with dyes, liquid crystals, quantum dots, and magnetic nanoparticles. We generated core-shell particles, microcapsules, Janus and three-phasic polymer particles. Control over the number of cores per droplet was achieved by manipulating the flow rates of liquids in the microchannels. We further investigated the hydrodynamic mechanism underlying the emulsification of droplets, which helps in guiding scientists and engineers to utilize this technique. Second, we described the self-assembly of inorganic nanorods by using a striking analogy between amphiphilic ABA triblock copolymers and the hydrophilic nanorods tethered with hydrophobic polystyrene chains at both ends. We organized metal nanorods in structures with various geometries such as nanorings, nanochains, bundles, bundled nanochains, and nanospheres by tuning solely the quality of solvents. The self-assembly was tunable and reversible. This approach paved the way for the organization of anisotropic nanoparticles by using the strategies that are well-established for the self-assembly of block copolymers. We further described a systematic study of the self-assembly of polymer-tethered gold nanorods as a function of solvent composition in the system and the molecular weight of the polystyrene blocks. We found that the structure of the polymer pom-poms played an important role on the organization of polymer-tethered gold NRs. The 'supramolecular' assembly was governed by the competition between the end-to-end and side-by-side association of NRs and resulted in the controlled variation of the plasmonic properties of NRs, reflected in a 3-D plasmonic graph.

This thesis described the development of new strategies for the preparation of micro- and nano-structured polymer materials. In particular, this thesis focused on: i) the synthesis of polymer particles in microreactors, and ii) the self-assembly of inorganic nanorods. First, this thesis presented the synthesis of polymer particles and capsules with pre-determined sizes and narrow size distributions (CV<2%) in continuous microfluidic reactors. The method includes (i) the emulsification of monomers in a microfluidic flow-focusing device and (ii) in-situ solidification of droplets via photopolymerization. This microfluidic synthesis provides a novel strategy for the control over the shapes, compositions, and morphologies of polymer particles. In particular, we demonstrated the control over particle shapes by producing polymer ellipsoids, disks, rods, hemispheres, plates, and bowls. We produced polymer particles loaded with dyes, liquid crystals, quantum dots, and magnetic nanoparticles. We generated core-shell particles, microcapsules, Janus and three-phasic polymer particles. Control over the number of cores per droplet was achieved by manipulating the flow rates of liquids in the microchannels. We further investigated the hydrodynamic mechanism underlying the emulsification of droplets, which helps in guiding scientists and engineers to utilize this technique. Second, we described the self-assembly of inorganic nanorods by using a striking analogy between amphiphilic ABA triblock copolymers and the hydrophilic nanorods tethered with hydrophobic polystyrene chains at both ends. We organized metal nanorods in structures with various geometries such as nanorings, nanochains, bundles, bundled nanochains, and nanospheres by tuning solely the quality of solvents. The self-assembly was tunable and reversible. This approach paved the way for the organization of anisotropic nanoparticles by using the strategies that are well-established for the self-assembly of block copolymers. We further described a systematic study of the self-assembly of polymer-tethered gold nanorods as a function of solvent composition in the system and the molecular weight of the polystyrene blocks. We found that the structure of the polymer pom-poms played an important role on the organization of polymer-tethered gold NRs. The 'supramolecular' assembly was governed by the competition between the end-to-end and side-by-side association of NRs and resulted in the controlled variation of the plasmonic properties of NRs, reflected in a 3-D plasmonic graph.

En aquest treball, es presenta l'estudi de les propietats de fractura de films de polipropilè (PP) i copolímers etilè-propilè en blocs (EPBC) per mitjà de la tècnica del Treball Essencial de Fractura (EWF). Aquesta tècnica es mostra com una alternativa molt adapatada per a l'aplicació de la Mecànica de la Fractura a films dúctils, i permet separar l'energia total de fractura en un terme essencial, que fa referència al treball real de fractura, i un terme no essencial, relatiu a la dissipació d'energia de deformació plàstica al voltant del camí de fractura.En una primera part, s'estudien les condicions òptimes d'assaig de la técnica EWF per aplicar-la a films de polímers dúctils, analitzant la influència de variables d'assaig com són les dimensions de la proveta, la velocitat d'assaig o el mode de fractura.En una segona part, s'ha estudiat la relació entre els paràmetres de fractura obtinguts mitjançant la tècnica EWF i diferents propietats referents a l'estructura del material. Entre aquestes, s'ha analitzat la influència de les característiques cristal·lines, modificades per un procés de recuit previ als assajos, i del contingut d'etilè a diferents temperatures d'assaig. S'han aplicat nombroses tècniques de caracterització tant mecàniques i de fractura com físico-químiques.Els resultats mostren que el mètode EWF s'adapta bé a la necessitat de caracteritzar la fractura de films polimèrics, i permet estudiar la relació entre la seva estructura i les propietats de fractura que presenten. Alhora, es plantegen diferents modificacions del mètode que permeten potenciar les seves possibilitats. S'observa que al millorar la perfecció cristalina dels materials estudiats, el terme essencial augmenta en detriment del terme no essencial. També es demostra que la presència d'etilè en els EPBC minimitza la gran dependència que presenten les propietats de fractura del PP homopolímer en variar la temperatura, i es relaciona aquest comportament amb els canvis dels mecanismes de deformació predominants en el material. / En este trabajo, se presenta el estudio de las propiedades de fractura de films de polipropileno (PP) y copolímeros etileno-propileno (EPBC) por medio de la técnica del Trabajo Esencial de Fractura (EWF). Esta técnica se muestra como una alternativa muy adaptada para la aplicación de la Mecánica de la Fractura en films dúctiles, y permite separar la energía total de fractura en un término esencial, que hace referencia al trabajo real de fractura, y un término no esencial, relativo a la disipación de energía de deformación plástica alrededor del camino de fractura.En una primera parte, se estudian las condiciones óptimas de ensayo de la técnica WF para aplicarla a films de polímeros dúctiles, estudiando la influencia de variables de ensayo como son las dimensiones de probeta, la velocidad de ensayo o el modo de fractura.En una segunda parte, se ha estudiado la relación entre los parámetros de fractura obtenidos mediante la técnica EWF y distintas propiedades referentes a la estructura del material. Entre éstas, se ha analizado la influencia de las características cristalinas, modificadas por un proceso de recocido previo a los ensayos, y del contenido de etileno a diferentes temperaturas de ensayo. Se han aplicado numerosas técnicas de caracterización, tanto mecánicas y de fractura como físico-químicas.Los resultados muestran que el método EWF se adapta bien a la necesidad de caracterizar la fractura de films poliméricos, y permite estudiar la relación entre su estructura y las propiedades de fractura que presentan. También se plantean diferentes modificaciones del método que permiten potenciar sus posibilidades. Se observa que al mejorar la perfección cristalina de los materiales estudiados, el término esencial aumenta en detrimento del término no esencial. También se demuestra que la presencia de etileno en los EPBC minimiza la gran dependencia que presentan las propiedades de fractura del PP homopolímero al variar la temperatura, y se relaciona este comportamiento con los cambios de los mecanismos de deformación predominantes en el material. / In this work, the study of the fracture properties of polypropylene (PP) and ethylene-propylene block copolymers (EPBC) films by means of the Essential Work of Fracture (EWF) method is presented. This method is considered as a suitable alternative for applying Fracture Mechanics to ductile films, allowing the separation of the total fracture energy into two different items: an essential term, related to the actual fracture work, and a non essential term, related to the plastic deformation energy dissipation occurring in the region surrounding the fracture path.In a first part, the optimal EWF method test conditions for ductile plastic films are studied, by analysing the influence of such test variables as the specimen dimensions, the test rate or the fracture mode.In a second part, the relationship between the fracture parameters obtained by applying the EWF method and different materials structural properties are studied. Among these properties, the influence of the crystalline characteristics, modified by an annealing process before the tests, and that of the ethylene content at different test temperatures have been analysed.Various mechanical, fracture and physico-chemical characterisation techniques have been applied.The results show that the EWF method is very suitable to assess the fracture of polymeric films, and therefore to study the relationship between their structure and the fracture properties that they present. In addition, various modifications of the method are proposed in order to improve its possibilities.It is observed that as the crystalline perfection grows, the essential term increases but the non-essential term decreases. It is also shown that the ethylene presence in the EPBC minimises the strong temperature dependence shown by the fracture properties of the PP homopolymer. This behaviour is related to the predominant deformation mechanisms in the material. / Cet ouvrage présente l'étude des propriétés de rupture de films de polypropylène (PP) et de copolymères éthylène-propylène en blocs (EPBC) par moyen de la methode du Travail Essentiel de Rupture (EWF). Cette technique se révèle comme une alternative très adaptée à l'application de la Mécanique de la Rupture aux films ductiles, et permet la séparation de l'énergie totale de rupture en un terme essentiel, qui fait référence au travail réel de rupture, et en un terme non essentiel, relatif à la dissipation d'énergie de déformation plastique autour du chemin de rupture.Dans une première partie, les conditions optimales d'essai de la technique EWF pour l'application aux polymères ductiles sont étudiées, tout en analysant l'influence de variables d'essai telles que les dimensions de l'éprouvette, la vitesse de l'essai, ou le mode de rupture. La deuxième partie est consacrée à l'étude de la relation entre les paramètres de rupture obtenus par la méthode EWF et différentes propriétés de la structure du matériau. Parmis celles-ci, nous avons analysé l'influence des caractéristiques cristallines, modifiées par un processus de recuit préalable aux essais, et de l'effet du contenu en éthylène à différentes températures d'essai. Plusieurs techniques de caractérisation, aussi bien mécaniques, que de rupture, que physico-chimiques ont été utilisées.Les résultats montrent que la méthode EWF est très adaptée à la caractérisation de la rupture de films de polymères, et permet d'étudier la relation entre leur structure et leurs propriétés de rupture. Nous présentons, aussi, différentes approches modifiées de la technique EWF qui permettent d'accroître son potentiel. Il est observé que, quand la perfection cristalline des matériaux étudiés augmente, le terme essentiel augmente lui aussi, mais le terme non essentiel présente une tendance opposée. De même, il est démontré que la présence d'ethylène dans les EPBC a un effet de minimisation de l'importante dépendence que le PP homopolymère présente vis-à-vis de la température, et ce comportement est relié aux changements des mécanismes de déformation prédominants dans le matériau.

An intracranial aneurysm can be a serious, life-threatening condition which may go undetected until the aneurysm ruptures causing hemorrhaging within the brain. The typical treatment method for large aneurysms is by embolization using platinum coils. However, in about 15% of the cases treated by platinum coils, the aneurysm eventually re-opens. The solution to the problem of aneurysm recurrence may be to develop more bio-active materials, including certain polymers, to use as coil implants. In this research, a shape memory polymer (SMP) was investigated as a potential candidate for aneurysm coils. The benefit of a shape memory polymer is that a small diameter fiber can be fed through a micro-catheter and then change its shape into a three-dimensional configuration when heated to body temperature. The SMP was tested to determine its thermo-mechanical properties and the strength of the shape recovery force. In addition, composite specimens containing tantalum filler were produced and tested to determine the mechanical effect of adding this radio-opaque metal. Thermo-mechanical testing showed that the material exhibited a shape recovery force a few degrees above Tg. The effects of the metal filler were small and included depression of Tg and recovery force. SMP coils deployed inside a simulated aneurysm model demonstrated that typical hemodynamic forces would not hinder the shape recovery process. The x-ray absorption capability the tantalum-filled material was characterized using x-ray diffractometry and clinical fluoroscopy. Diffractometry revealed that x-ray absorption increased with tantalum concentration, however, not as the rule of mixtures would predict. Fluoroscopic imaging of the composite coils in a clinical setting verified the radio-opacity of the material.