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The synthesis and properties of diazonium (perfluoroalkyl) benzenesulfonylimide (PFSI) zwitterions are described. The general procedures for the diazonium PFSI zwitterions involve three steps: (1) a coupling reaction, (2) a reduction reaction and (3) a diazotization reaction. These novel diazonium PFSI zwitterions represent a new versatile class of remarkably stable diazonium materials with potential for modification of carbon supports for electrodes in proton exchange membrane (PEM) fuel cells.

The synthesis and properties of diazonium (perfluoroalkyl) benzenesulfonylimide (PFSI) zwitterions are described. The general procedures for the diazonium PFSI zwitterions involve three steps: (1) a coupling reaction, (2) a reduction reaction and (3) a diazotization reaction. These novel diazonium PFSI zwitterions represent a new versatile class of remarkably stable diazonium materials with potential for modification of carbon supports for electrodes in proton exchange membrane (PEM) fuel cells.

La chimie d'interface du diazonium a progressé au cours des dernières années et s'est pratiquement impliquée dans tous les domaines de la science et technologie des matériaux. L’utilisation des sels de diazonium est justifiée par le fait qu’ils adhèrent aux surfaces avec de fortes énergies de liaison, en particulier sur le carbone sp², ce qui en fait d’excellents agents de couplage pour les polymères aux surfaces. Dans ce contexte, nous avons travaillé sur deux types de nanohybrides de nanotubes de carbone (NTC) : NTC-polytriazole (NTC-PTAz) et NTC-colorant. Le nanohybride NTC-PTAz a été synthétisé par polymérisation « click » en surface. Pour ce faire, les NTCs ont été greffés de groupes 4-azidophényle à partir du sel de diazonium correspondant. Le NTC modifié (NTC-N3) a servi de support pour une polymérisation confinée en surface de type polyaddition générant ainsi le nanohybride NTC-PTAz. Ce matériau a été caractérisé par ATG, XPS, IR et Raman. Ses applications potentielles sont dans le développent d’adsorbants de métaux lourds, l’immobilisation de nanocatalyseurs ou pour le stockage des gaz. La seconde partie de la thèse est plus étoffée et porte sur les nanotubes de carbone greffés de colorants diazotés Rouge Neutre (NR), Azure A (AA) et Rouge Congo (CR). L’analyse fine de ces matériaux a révélé une très forte adhésion des colorants aux NTCs et les couches superficielles ont des épaisseurs de 2 à 6 nm, sont homogènes et continues. Les NTC-colorant ont été incorporés dans des matrices élastomères de type EVA pour la réalisation d’actionneurs opto-thermiques implantés dans des pads pour non-voyant. Dans les matrices EVA, les NTCs greffés de colorants servent à capter la lumière et induire un changement de forme dans le pad qui soit palpable par le non voyant (250 µm). Les matrices EVA renforcées de nos nanotubes greffés de colorants ont été réalisées et testées par analyse mécanique dynamique. Les composites NTC/colorant-EVA sont flexibles et prometteurs pour le développement de nouveaux types des pads tactiles pour les non-voyants. Les nanohybrides NTC-NR ont servi comme capteurs chémo-résistifs pour la reconnaissance moléculaire de l’acétone.Dans une dernière application, le nanohybride CNT-CR a été étudié en tant qu’électrocatalyseur pour l’oxydation directe du méthanol. Des résultats intéressants ont été obtenus avec ces nanohybrides mais des améliorations significatives (rapport 3) des propriétés électrocatalytiques ont été obtenues avec des CNT-CR décorés avec des nanoparticules d'or. Le système électrocatalytique nouvellement conçu pourrait être considéré pour différentes applications prometteuses, notamment les capteurs, les biocapteurs, les catalyseurs hétérogènes pour les piles à combustible. Pour résumer, les nanohybrides à base de CNT nouvellement conçus présentent des performances uniques attribuées à la polyvalence de la chimie d'interface du diazonium pour la fixation efficace de couches moléculaires et macromoléculaires fonctionnelles. Les nanohybrides novateurs servent de blocs de construction pour la conception de matériaux nanocomposites à hautes performances potentiellement utiles dans les nouveaux défis socio-économiques tels que l’environnement, la biomédecine et l’énergie / Diazonium interface chemistry has progressed over the last few years and practically involved in all areas of materials science and engineering. The rationale for employing diazonium salts is that they attach to surfaces with remarkable bond energies, particularly on sp² carbon materials, making them an ideal coupling agent for polymers to surfaces In this context, novel CNT-polytriazole (CNT-PTAz) and CNT-dye nanohybrids were designed and thoroughly characterized. First, CNT-PTAz nanohybrid was prepared by click polymerization: multiwalled carbon nanotubes (CNTs) were modified with azidophenyl groups (CNT-N3) from 4-azidobenzenediazonium precursor and served as nanoscale platform for the surface confined polyaddition. The CNT-PTAz nanohybrid was characterized by TGA, XPS, IR, and Raman. The robust CNT-PTAz is robust and has potential in developing heavy metal adsorbents, nanosupport for catalysts or for gas storage. In the second major part, we grafted CNT with diazotized Neutral red (NR), Azure A (AA) and Congo Red (CR) dyes by simple, spontaneous reaction of the diazonium salts and CNTs in water, at RT. A thorough investigation of the nanohybrids showed that the adhesion is strong (CNT-dye C-C bond energy higher than 150 kJ/mol), and the layer is uniform. These nanohybrids further served to reinforce ethylene-vinyl acetate (EVA) an elastomeric matrix. The reinforced matrix is flexible and serves as optothermal actuators where the grafted dye catches the light to induce mechanical changes in the matrix monitored by dynamic mechanical analysis. CNT/dye-reinforced EVA is a promising flexible composite for developing new types of visual-aid tablet for visually impaired people. The versatile CNT-dye nanohybrids are also unique chemiresistive gas sensors for the molecular recognition of acetone vapours. In a final application, CNT-CR nanohybrid was investigated as an electrocatalyst for the Direct Oxidation of Methanol. Interesting results were obtained with these nanohybrids but significant improvements (3-fold) of the electrocatalytic properties were achieved with CNT-CR decorated with gold nanoparticles. The newly designed electrocatalytic system could be regarded for different promising applications most likely as for sensors, biosensors, heterogeneous catalysts for fuel cells and for nanotechnology To summarize, newly designed CNT-based nanohybrids have unique performances ascribed to the versatility of the diazonium interface chemistry in efficiently attaching functional molecular and macromolecular layers. The novel nanohybrids serve as building blocks for designing high performance nanocomposite materials relevant to challenging timely social economic issues, namely environment, biomedicine and energy

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Since the invention of the atomic force microscope (AFM), this technology has had profound implications in the study of material science and molecular biology. The ability to visualize and perform quantitative analysis of the nanoscale properties of surfaces has provided great insights into these nanoscale landscapes. The present dissertation manuscript exploits this technology for the measurement of charge transport through molecular films and the development of combinatorial force microscopy. Firstly, this work probed, for the first time, charge transport through molecular films derived from diazonium salts grafted to carbon electrodes using conductive atomic force microscopy. We found the charge transport properties of a molecular junction are dependent upon the chemical structure of the molecular film. We also investigated the effect of molecular film compression and deformation has on charge transport. In this, we observed increases in current densities associated with increases in applied load to the molecular film. Furthering these initial findings, PPF/NAB/Cu molecular junctions were fabricated having junction sizes ranging between micro-scale and nanoscale. The charge transport experiments reveal an agreement of electron transport properties between the metal deposited PPF/NAB/Cu junction and a PPF/NAB/Cu AFM tip junction at an applied load of approximately 60nN. This form of molecular layer charge transport control may potentially open new horizons for integration of molecular films into the microelectronics industry. This dissertation manuscript also describes the development of the quantitative interrogation opposing chemical libraries involved in combinatorial inverted atomic force microscopy. Tipless cantilevers were patterned with chemically modified nanorods. These modified nanorods were then used as chemical identifiers during a combinatorial force microscopy experiment and for the first time 16 interactions were monitored within one experiment in a continuous medium. Thus, providing excellent for the validation that combi-AFM is a truly quantitative high-throughput technology.

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This thesis describes the preparation of surface-attached monolayer tethers from electroreduction of aryldiazonium ions using a protection-deprotection strategy. Monolayers of ethynylphenyl, carboxyphenyl, aminophenyl and aminomethylphenyl were prepared. Glassy carbon (GC) and pyrolysed photoresist film (PPF) surfaces were modified electrochemically and characterised by redox probe voltammetry. The monolayer tethers were coupled with electro-active ferrocenyl (Fc) and nitrophenyl (NP) groups for the indirect electrochemical estimation of the surface concentration. Film thickness measurement was carried out using an atomic force microscopy (AFM) depth profiling technique. The surface concentration and film thickness measurement results were consistent with the formation of monolayer films after removal of the protecting groups. Preparation of mixed monolayers was studied using three different modification strategies: i) grafting from a solution containing two different protected aryldiazonium ions, ii) sequential grafting of two different protected aryldiazonium ions, and iii) grafting of protected aryldiazonium ions followed by removal of the protecting group and reaction of an amine or carboxylic acid derivative directly with the GC surface. The composition of the mixed layer prepared using the first method is difficult to control, whereas the possibility of multilayer formation cannot be discounted using the second method. Multilayer formation is unlikely using the third method. The electrocatalysis of oxygen reduction at mixed monolayer films was investigated briefly. The origin of the two reduction peaks frequently observed for electroreduction of aryldiazonium ions at carbon surfaces was studied. Electroreduction was carried out at GC and HOPG surfaces. The reduction peak at the more positive potential is surface sensitive, while the peak at the more negative potential is not. However, both reduction peaks lead to deposition of films and it is tentatively proposed that the more positive peak corresponds to reduction at a ‘clean’ GC electrode, and the more negative peak corresponds to reduction at the already grafted layer.

L'utilisation d'un électrolyte aqueux pour la technologie Li-ion devrait permettre des performances en termes de puissance et de coût tout en garantissant une sécurité de fonctionnement et un impact neutre vis-à-vis de l'environnement. Cette technologie utilise des composés d'insertion du lithium fonctionnant habituellement en milieu organique dont le choix doit être adapté à un électrolyte aqueux, présentant une fenêtre de stabilité électrochimique réduite. Le travail de thèse porte dans un premier temps sur la sélection des différents éléments constituant un accumulateur Li-ion aqueux: choix de l'électrolyte, des collecteurs de courant, des liants d'électrode et des matériaux d'électrode. Les performances électrochimiques en milieu aqueux de différents composés d'insertion du lithium ont été évaluées. Afin d'augmenter la fenêtre de stabilité électrochimique de l'électrolyte aqueux, la passivation des électrodes par réduction de sels de diazonium a été réalisée. L'influence de la nature des sels de diazonium et de l'épaisseur des films sur les performances électrochimiques des électrodes a été évaluée par diverses techniques, voltampérométrie et impédance électrochimique. Les résultats obtenus montrent l'impact positif des dépôts obtenus vis-à-vis de l'augmentation de la surtension de réduction de l'eau. Ces travaux ouvrent la voie à des perspectives prometteuses sur cette technologie Li-Ion aqueuse. / The use of aqueous electrolytes should permit to improve power performances and decrease significantly the battery cost. Moreover, these kind of electrolytes guarantee a safely use with reduced consequence on the environment. This technology use active materials enable to inserted and deinserted lithium ion. But the choice of lithium insertion compounds was guided and limited by the water electrochemical stability. We selected each component of the Li-ion cell which could be used in aqueous electrolyte; the lithium salt, the binder and the active material. The electrochemical performances of several active materials in aqueous electrolyte were evaluated. In order to increase the Li-ion cell tension, a passive film was form on the electrode surface by diazonium salt reduction. Influence of molecule design and film thickness were studied by voltammetry and electrochemical impedance spectroscopy. The results clearly show the interest of the formation of these films for lowering the reduction potential of water on glassy carbon and practical Li-ion electrode. This study opens very promising route for the aqueous lithium batteries.