Le but du projet est de synthétiser un film de polymères à double mémoire de formes avec une sensibilité à la lumière ainsi qu’à un champ magnétique. Afin de rendre le polymère sensible à ces stimuli, des nanoparticules d’oxyde de fer (II,III) furent enrobées d’une couche de polydopamine. Par après, du polycaprolactone et du poly(caprolactone-co-pentadecalactone) furent synthétisés par polymérisation enzymatique à ouverture de cycle. Les polymères furent méthacrylés en fin de chaînes, remplaçant le groupe alcool par une double liaison qui est par la suite utilisée pour une réticulation. Les films de polymères étaient obtenus en combinant les nanoparticules et les polymères via une réaction click de type « thiol-ène ». Des films avec une teneur de nanoparticules de 0 à 1 pour cent en poids furent ainsi synthétisés. L’alternance entre deux formes était possible grâce à deux phénomènes physiques : l’élongation induite par cristallisation et la contraction induite par la fusion. Ces phénomènes sont causés par la fusion et la cristallisation du polycaprolactone, tandis que le poly(caprolactone-co-pentadécalactone) restait maintenu dans un état solide cristallin sur la gamme de températures étudiée. Les films de polymères changeaient de forme en étant chauffés par exposition à la lumière. Les films avec nanoparticules se contractaient quand ils étaient exposés à la lumière et retournaient à leur forme originale quand la lumière était éteinte. Le chauffage par induction avec un champ magnétique alternatif fut aussi un succès. Les films avec nanoparticules se contractaient à l’intérieur d’une bobine de cuivre avec un champ magnétique présent lorsqu’un courant électrique circulait dans la bobine. Les films retournaient à leur forme d’origine lorsque le champ magnétique était coupé. Il fut observé que plus la teneur en nanoparticules au sein du film de polymères était élevée, le plus court le temps de réponse était avant qu’un mouvement de contraction ne soit observé. Aucun changement de volume ne fut observé en chauffant des échantillons de films de polymères de 20 à 60 °C, confirmant, dans les conditions actuelles d’évaluation, que la contraction induite par la fusion et que l’élongation induite par cristallisation se produisent sans causer un changement de volume du film. / The project goal is to synthesize a two-way shape memory polymer that is both magnetically and light responsive. To make the polymer responsive to these stimuli, iron oxide (II, III) nanoparticles with a polydopamine coating were first synthesized. Afterwards, polycaprolactone and poly(caprolactone-co-pentadecalactone) were synthesized by enzymatic ring-opening polymerization. The polymer was then methacrylated at the terminal positions, replacing the alcohol with a double bond which was then used for crosslinking. Polymer films were prepared by combining the nanoparticles and the polymer by a “thiol-ene” click reaction. Films containing from 0 to 1 weight percent of nanoparticles were synthesized. Switching between the two shapes was possible by two physical phenomena: crystallization induced elongation and melting induced contraction. These are caused by the fusion and crystallization of the polycaprolactone network, while the poly(caprolactone-co-pentadecalactone) is consistently maintained in its crystalline solid state in a specific temperature range. The polymer films changed shapes due to heating when exposed to light. Films with nanoparticles contracted when exposed to light and they returned to their original form when the light was turned off. Induction heating with an alternating magnetic field was also successful. The polymer film with magnetic nanoparticles contracted inside a copper coil when the magnetic field was generated by applying electric current to the coil. The film returned to its original shape when the magnetic field was turned off. It was found that the higher the content of nanoparticles in the polymer filler, the shorter the response time was before a contraction movement was observed. No change in the polymer volume during heating of a film sample from 20 to 60 °C was observed, confirming that melting induced contraction and crystallization induced elongation occurred without change in volume under conditions examined.

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In this research, we aimed to develop thin-film devices on a polymer substrate and an alternative 3D-printed device with macroelectrodes for treating gastrointestinal (GI) conditions. First, the fabrication of thin-film devices was demonstrated on a softening thiol-ene/acrylate polymer utilizing titanium nitride (TiN) as electrode material. This was achieved by utilizing cleanroom fabrication processes such as photolithography, wet and dry etching. The functionality of the device was shown by performing electrochemical characterization tests, mainly cyclic voltammetry, electrochemical impedance spectroscopy, and voltage transient. We synthesized a novel thiol-ene/acrylate polymer based on 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TATATO), trimethylolpropanetris (3-mercaptopropionate) (TMTMP), and polyethylene glycol diacrylate (PEGDA). We show that this stretchable shape memory polymer substrate is well suited for cleanroom processes. Finally, for the high throughput of the wearable devices with electrodes size 10 mm in diameter, we implemented single electrode fabrication using printed circuit boards (PCBs) and depositing gold (Au) and TiN on the plated side of PCBs utilizing the sputtering tool. This step was followed by the assembly of those single electrodes on the flexible 3D printed device. We showed that the TiN electrode material performed better in terms of charge storage capacity and charge injection capacity than the widely used stainless steel electrode material for wearables.

This research investigates the synthesis and manufacture of shape-memory polymer (SMP) systems for use in biomedical and commodity applications. The research centers on improving the mechanical properties of thermoset acrylate copolymers with memory properties at reasonable cost through various design and manufacturing techniques: high-strain polymer synthesis and radiation crosslinking. The research assesses combinations of linear monomers and a low density of crosslinker to characterize new functional materials and optimize emerging mechanical properties such as the glass transition temperature (Tg) and rubbery modulus (ER). Exploring materials with large recoverable strains, a model copolymer of photo-polymerized methyl acrylate (MA), isobornyl acrylate and crosslinker bisphenol A ethoxylate dimethacrylate was shown to strain above 800%, twice the previously published value for SMPs, and recover fully. In the quest to maximize fully recoverable strains, a new hybrid molecule nicknamed Xini, which serves as both an initiator and a crosslinker, was also theorized, synthesized, polymerized into SMP networks and characterized. In the past, thermoset SMPs were made into complex shapes using expensive top-down techniques. A block of polymer was made and custom machining was required to craft complex parts. This prohibited devices in cost-competitive commodity application spaces. This research has proposed and validated a new method for accurately tuning the thermomechanical properties of network acrylates with shape-memory properties: Mnemosynation, eponymously named for the Greek goddess of memory. This novel manufacturing process imparts long term 'memory' on an otherwise amorphous thermoplastic material utilizing radiation-induced covalent crosslinking, and can be likened to Vulcanization, which imparts strength on natural rubber utilizing sulfur crosslinks. Adjustment of ER in the range from below 1 MPa to above 13 MPa has been demonstrated. ER was tailored by varying both radiation dose between 5 and 300 kGy and crosslinker concentration between 1.00 and 25.0 wt%. Tg manipulation was demonstrated between 23 ˚C and 70 ˚C. Mnemosynation combines advances in radiation grafting and acrylic SMP synthesis to enable both traditional plastics processing (blow molding, injection molding, etc.) and control of thermoset shape-memory properties. Combining advances in both high strain polymer synthesis and radiation crosslinking, a new paradigm in SMP composites manufacture-namely, that materials can be designed to enhance strain capacity at moderate stress, rather than maximum strength-was established. Various fibers with very different mechanical properties were impregnated with SMPs and thermo-mechanically assessed to develop an understanding of the technical parameters necessary to craft self-adjusting, multi-actuated, SMP-fiber composite orthopedic casts. This exploration syncs with the overarching aim of the research, which is to understand the fundamental scientific drivers necessary to enable new devices mass-manufactured from acrylate copolymers and optimize their emerging mechanical properties.

Ces travaux de thèse proposent utiliser les polymères à mémoire de forme comme moyen de contrôle desvibrations des structures. Outre hystérésis de mémoire qui est classiquement mis en avant, ces matériauxpossèdent des propriétés amortissantes intrinsèques qui sont d'autant plus intéressantes lorsque l’effetmémoire de forme est important. Dans un premier temps une caractérisation des propriétés mécaniques dutBA/PEGDMA, polymère à mémoire de forme de l'étude, est effectuée par analyse dynamique mécanique.Un modèle rhéologique basé sur lʹéquivalence temps-température, le 2S2P1D, est utilisé pour rendre comptedu comportement viscoélastique du polymère. Dans un deuxième temps, une campagne expérimentale estmenée, sur une large bande de fréquences et de températures, grâce à divers moyens expérimentaux(statiques, modaux, nano-indentations, ultrasons, dynamiques hautes fréquences, microscopie acoustique)afin de définir le domaine de validité, fréquentiel et thermique, du modèle rhéologique. Dans un troisièmetemps, le polymère à mémoire de forme est intégré à une structure composite de type sandwich pour mettreen évidence le pouvoir amortissant impressionnant du matériau. Enfin, une méthodologie de contrôle delʹamortissement par la température est proposée. En effet, la dissipation d’énergie dans le sandwich sʹavèrecontrôlable, la température permettant d’ajuster la rigidité et le facteur de perte du tBA/PEGDMA pour unamortissement optimal sur une large bande de fréquences. / This work proposes to use shape memory polymers to control structural vibrations. These materials exhibit amemory hysteresis which is practically associated with intrinsic damping properties which are very highwhen the memory effect is strong. First, a thermomechanical characterization of the shape memory polymerof interest (tBA/PEGDMA) is performed by dynamic mechanical analysis. A rheological model based on timetemperaturesuperposition is used to represent the viscoelastic behavior of the polymer. Secondly, anexperimental campaign is performed over a wide frequency and temperature range, through variousexperimental techniques (static, modal, nanoindentation, ultrasounds, high frequency dynamic analysis,acoustic microscopy) to define the area of validity, in frequency and temperature, of the rheological model.Third, the shape memory polymer is integrated into a composite sandwich structure to highlight the awesomedamping capabilities of the material. Finally, a damping tuning methodology by temperature control isproposed. Indeed, the power dissipation in the sandwich is related to physical properties of the tBA/PEGDMA core which are temperature-controlled to optimize the damping over a given frequency range.

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The epoxy based polymer is one of the very common polymers, which was used as a host to create new better materials - nanocomposites. This thesis focused on the improvement of the thermomechanical properties of the epoxy thermosets without deteriorating their existing benefits and on further potential application of this knowledge in "smart" systems. The largest part of this work is dedicated to the reinforcement of epoxy thermosets by in situ generated silica and synthesis of organic-inorganic nanocomposites. Borontrifluoride monoethylamine (BF3MEA) was chosen as effective catalyst for the formation of nanosilica in epoxy-amine network matrix under nonaqueous (non-hydrolytic) sol-gel process. We proposed the mechanism of the nonaqueous sol-gel procedure, studied the structure evolution during the nanocomposite formation, and also determined the structure, morphology and thermomechanical properties of the obtained epoxy-silica nanocomposites. Significant attention in this work was given to the application of coupling agent and ionic liquids to improve compatibilization of the organic matrix and the inorganic part. As a result of the nonaqueous sol-gel process optimization by combination of the tetramethoxysilane (TMOS) and the coupling agent glycidyloxypropyltrimethoxysilane (GTMS), the high-Tg and...