Les mousses solides, en polyuréthane, sont connues pour avoir des propriétés de transports intéressantes telles que des faibles pertes de charges engendrées ou une grande surface spécifique développée permettant une bonne évacuation de la chaleur. Cependant, elles ne sont pas utilisées en tant que support catalytique à cause des méthodes de déposition actuelles qui provoquent une altération de leurs propriétés mécaniques. Nous avons tout d’abord utilisé une nouvelle méthode de déposition basée sur la polydopamine(PDA), un polymère aux propriétés intéressantes, d’adhésion et de réduction. La PDA va venir recouvrir de manière homogène notre support puis va servir d’intermédiaire pour le dépôt de différentes phases active, qu’elles soient commerciales ou synthétisées in-situ. Par la suite, nos supports ont été employés dans plusieurs réactions, qu’elles soient monophasiques (liquide) ou bi-phasiques (gaz/liquide), afin de mettre en avant l’efficacité et la stabilité du dépôt de nos phases actives. De plus, il nous a été possible de déposer une phase active intéressante pour la production d’hydrogène. L’étude cinétique de cette réaction à basse température a été réalisée et a montré des résultats prometteurs pour le domaine des énergies renouvelables. Enfin, la dernière partie est consacrée à la mise en place de notre support structuré au sein d’un réacteur innovant, permettant d’utiliser les propriétés mécaniques du dit support afin d’améliorer les propriétés de transfert de matière / Solid foams, made with polyurethane, are well known for their interesting transport properties such as low pressure drop or high specific surface area. However, there are not used as catalytic support due to actual deposition method which causes an alteration of their mechanical properties. First, we used a new deposition method using polydopamine (PDA), a polymer with interesting adhesive and reducing properties. The PDA layer will cover homogenously our support then will act as intermediary for active phase deposition, whether they are commercially available or synthetized in-situ. Afterward, our supports were tested for several catalytic reactions, whether monophasic (liquid phase) or biphasic (gas/liquid) to show the active phase efficiency and stability. Furthermore, we successfully deposited a good active phase (cobalt) for hydrogen production. Kinetic study at low temperature were done and shown promising results for sustainable energy production. Finally, the last part was devoted to the use of our soft structured catalytic support within a new reactor, allowing to use its mechanical properties to improve mass transfer

Les matériaux à base de polydopamine (PDA) s’inspirent de la forte adhésion du byssus de la moule sous l’eau. L’oligomérisation de la dopamine dans un milieu basique permet la formation de revêtement de PDA sur n’importe quel matériau. En plus de la simplicité du procédé celui-ci est vert et versatile. La PDA a des propriétés similaires aux mélanines, d’où son utilisation dans le domaine des phénomènes de conversion d’énergie, de l’environnement et du biomédical. Cependant la structure de la PDA étant inconnue, l’élaboration de matériaux basés sur la relation structure propriétés est difficile. L’un des buts de cette thèse a été de comprendre cette relation pour élaborer de nouveaux matériaux de PDA. En choisissant l’oxydant adéquat nous avons déposé un film épais, superhydrophile et biocompatible sur n’importe quels substrats. De plus nous avons découverts la possibilité de former des films de PDA à l’interface air/eau. L’étude de ce phénomène a permis de former des membranes autosupportées et stimuli responsives. / Polydopamine (PDA) materials are inspired from mussels’ byssus strong adhesion underwater. The oligomerization of dopamine in a basic medium allows forming a PDA coating on virtually any materials. In addition to the simplicity, ecofriendly and versatility of the deposition method, PDA has properties similar to those of melanin pigments and displays many outstanding properties. Thus PDAis widely used in energy, environmental and biomedical sciences. However design of PDA based new materials with tailored properties is a challenge since its structure is still unknown. In that sense one of the aims of this thesis is to gain knowledge in PDA structure-property relationship in order to design PDA materials with new properties. By choosing the appropriate oxidant we deposited thick and superhydrophylic films on any materials for the elaboration of low fouling and biocompatible surfaces. Additionally we discovered the possibility to form PDA films at the air/water interface. The investigation of this phenomenon led to the formation of stimuli responsive free standing membranes.

No description available.

Les matériaux poreux représentent une solution idéale en ingénierie tissulaire car leur structure peut offrir un environnement tridimensionnel aux cellules similaire à leur matrice extracellulaire tout en maintenant de bonnes propriétés mécaniques. Une première partie de cette thèse consiste à développer des matériaux poreux en polyuréthane (PU), dont l’architecture est contrôlée pour favoriser au mieux la survie et la croissance des cellules. Ces matériaux sont combinés à des traitements de surface (revêtement de polydopamine (PDA) et traitement plasma) pour augmenter notamment l’adhésion des cellules. Nous avons pu démontrer que le diamètre des interconnexions (i.e. l’ouverture connectant deux pores adjacents) impacte profondément la survie et l’organisation des cellules à long terme dans le matériau. Le revêtement de PDA s’est révélé efficace pour des cellules de type fibroblaste, alors que le traitement plasma favorise la colonisation des cellules souches mésenchymateuses (MSCs). Par ailleurs, nous avons étudié l’influence de la formulation du PU sur les capacités d’adhésion des cellules au matériau. Nous avons démontré que pour un ratio donné entre les réactifs, l’adhésion des cellules peut être exclue ou permise. Finalement, nous avons mis un gel de peptides auto-assemblés dans les pores du matériau pour fournir aux cellules un environnement similaire à leur matrice extracellulaire. Nous avons pu montrer que le gel permet d’augmenter la prolifération des MSCs. / Porous materials are an ideal solution in tissue engineering since they can provide a three-dimensional environment to the cells that is close to their extracellular matrix while keeping suitable mechanical properties. In the first part of this Thesis we develop porous materials made from polyurethane (PU) whose architecture is controlled to allow cells colonisation and growth. These materials are subsequently surface-treated (polydopamine (PDA) coating and plasma treatment) to enhance the adhesion of the cells. We were able to show that the interconnection diameter (i.e. the aperture connecting two adjacent pores) has an important impact on the long-term cell survival and organization in the material. Polydopamine coating was shown to be efficient for fibroblasts, whereas plasma treatment promoted mesenchymal stem cells (MSCs) colonisation. Besides, we also studied the influence of the PU formulation on the adhesion capacity of the cells. We demonstrated that at a given ratio between the reactants, cell adhesion could be allowed or prevented. Finally, we put a hydrogel of self-assembled peptides inside the pores of the material to provide an environment close to the extracellular matrix for the cells. We could show that the gel increases the proliferation ability of MSCs. In summary, this Thesis puts forward the important interplay between material properties and morphology of porous scaffolds.

A systematic study of the surface-initiated polymerisation kinetics of a relatively new type of atom transfer radical polymerisation (ATRP), activators regenerated by electron transfer (ARGET) ATRP, is first demonstrated in this report. Poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(methyl methacrylate) (PMMA) were successfully grown from silicon surfaces at room temperature by surface-initiated ARGET ATRP using a "3rd generation" cationic macroinitiator. The polymer films were analysed by ellipsometry, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). With the initial experiment showing that water accelerated conventional ATRP but made it less controlled, the effect of solvent on ARGET ATRP was also evaluated. The living character of ARGET ATRP was demonstrated by successfully reinitiating PHEMA-grafted silicon wafers to grow a second block of PHEMA. Initiator density was shown to have a great effect on the growth rate of PHEMA film thickness on silicon surfaces by comparing the ARGET ATRP growth of PHEMA films using two different initiators, "1st generation" and "3rd generation" cationic macroinitiators, which have different ratios of initiating groups to positive charge. Another type of initiator for ATRP systems, an amide silane, was then investigated as an alternative to polyelectrolyte macroinitiators to avoid degrafting. The effects of solvent, 2, 2′ bipyridyl (bpy) ligand concentration and different types of reducing agent on the growth of PHEMA film from amide-initiator coated silicon wafers by ARGET ATRP were then explored at room temperature. However, it was found that the swings in the uncontrolled laboratory ambient temperature caused inter-sample and inter-experiment variability and so could make the evaluations inaccurate or even wrong. An investigation of temperature on ARGET ATRP showed a dramatic effect on the polymerisation rate. The higher the temperature, the faster the polymerisation proceeded. Therefore, the effects of solvent, ratio of bpy to Cu and reducing agent on the ARGET ATRP growth of PHEMA brushes from amide initiator-coated silicon wafers were re-evaluated at a constant temperature, 30 °C. The development of a polydopamine-based initiator, which was designed to be able to be immobilised on a wide range of surfaces, is then presented in this report. Polydopamine was first shown to be able to deposit on various types of material surfaces by oxidative polymerisation in aqueous solution. Bromoester initiating groups for ATRP systems were incorporated into polydopamine coatings by reacting a fraction of the dopamine monomer with 2-bromoisobutyryl bromide (BIBB) before polymerisation. The modified polydopamine initiator film grew at a comparable rate to unmodified polydopamine, with a 45 nm being grown in 24 hours. Successful incorporation of initiator groups was confirmed by XPS and FTIR, and by the growth of PMMA and PHEMA polymer brushes by ARGET ATRP from the polydopamine initiator coatings. A PMMA brush with a thickness of 239 nm was grown in 72 hours, indicating that the grafting density is sufficiently high to be in the brush regime. This initiator was demonstrated to be able to deposit on a range of substrates, such as metals (steel) and polymers (polystyrene), and successfully initiate polymer growth, demonstrating its broad applicability. The assessment of ARGET ATRP as a simple and effective tool for interfacial shear strength improvement in cellulose-based fibre reinforced thermoplastic composites is finally presented. It was demonstrated by control experiments that grafting polystyrene on glass fibre surfaces via ARGET ATRP greatly improved the interfacial adhesion between glass fibres and a high-impact polystyrene (HIPS) matrix, although a specific value of interfacial strength was not obtained due to failure of the modified glass fibre composite samples in areas other than the interface. It was then demonstrated that PMMA was successfully grown from the surfaces of polydopamine initiator coated cotton fibre and BIBB-modified cotton fibre by ARGET ATRP. Polydopamine initiator was shown to be a better initiator for cotton fibre than BIBB, possibly since the adsorbed water on cotton fibres can react with BIBB. The improvement of interfacial adhesion between cotton fibres and a PMMA matrix by grafting PMMA on the cotton surface was assessed by peel testing of cotton fibres pressed into PMMA sheets. There is a clear trend in the relationship between the peeling force and growth time of PMMA on the cotton fibre by ARGET ATRP, although the inter-sample reproducibility is not good.

This diploma thesis deals with the optimization of the preparation of molecularly imprinted (MIP) nanoparticles doped with metal ions, selective for the selected protein. In this work, the model protein – chymotrypsinogen A was chosen as a template. The free radical polymerization method was used for the preparation of molecularly imprinted nanoparticles. Dopamine was used as a functional monomer because it is able to bind metal ions to each other. It also undergoes very rapid oxidative polymerization under alkaline conditions without the need for the addition of polymer reaction initiators. MIP optimization was performed by capillary electrophoresis with UV-Vis detection. The MIP thus prepared can serve as recognition elements in immunohistochemical analyzes that use LA-ICP-MS as a detection method. Their applicability for immunohistochemistry was studied using the dot block method.

Orientador: Ana Paula Risifni Alves Claro / Resumo: Infecção bacteriana sempre foi uma grande preocupação para medicina, principalmente devido a capacidade de adaptação de bactérias, e consequente aparecimento de cepas resistentes aos medicamentos convencionais. Como alternativa a esta problemática, estudos vem comprovando a eficácia de íons metálicos, no combate a diferentes tipos de microrganismos. Dentre metais com propriedade bactericida, há o gálio, elemento com interessante conjunto de propriedades que possibilitaram seu uso em tratamentos terapêuticos, entretanto sua ação bactericida ainda se encontra pouco explorada na literatura. Como forma veiculação deste metal, escolheu se a polidopamina, um polímero baseado em compostos presentes na composição de moluscos, os quais lhe confere m interessantes propriedades de adesão em diferentes superfícies e capacidade de ancoragem de íons ou moléculas. Com base nas informações expostas, a presente dissertação tem por objetivo produzir partículas de polidopamina com incorporação de gálio para aplicação biomédica . Para isso, inicialmente o polímero foi sintetizado a partir da polimerização do hidrocloreto de dopamina em ambiente alcalino, com pH ajustado em 9,0 a temperatura ambiente e com agitação magnética. Em seguida o material foi centrifuga do e seco. Em fase posterior, a incorporação do gálio se deu a partir da dissolução de nitrato de gálio na presença das partículas previamente produzidas, sendo mantido em solução por 18 horas. O material resultante foi novamente centrifu... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

No description available.

Polydopamine (PDA) surfaces have attracted much attention, both for their innate capability as a versatile biomaterial and their standalone antibacterial and adhesive properties. However, the mechanics of PDA deposition as well as the attributes of PDA-coated surfaces remain relatively underexplored despite their adaptability and ease of deposition. Two polydopamine surfaces from literature, smooth and rough PDA (sPDA and rPDA), were compared to a novel surface, inverted PDA (iPDA), to further explore their mechanochemical and bioactive properties. The iPDA surface displayed, by design, a smoother topography when compared to sPDA, with smaller aggregate structures covering 2.7% of the overall surface. However, the chemical signature obtained via Raman spectroscopy of these aggregates shared remarkable similarities at the 1370 cm-1 peak with the rougher rPDA surface, leading to the conclusion that gas exchange at the solution surface may play a critical role in determining PDA subunit composition despite dissimilar deposition methods. Atomic force microscopy (AFM) analysis concluded that the iPDA surface was ~17% more adhesive than other PDA types, while also displaying relatively large hysteresis and a small Young’s modulus. Human osteoblastic MG-63 cells cultured on all three surfaces revealed that a smoother surface topography correlated to more pronounced anisotropic spread independent of cell size, while a serum-independent component was also noted. This work provides a clearer insight into the nature of polydopamine surfaces by the creation of a viable new deposition method, providing an analysis of its mechanochemical and bioactive properties as well as a deeper understanding of the PDA coating process.

No description available.