Pulsed field gradient (PFG) 1H NMR was used to characterize the mobility of ionic liquid cations in porous gas diffusion electrode (GDE) frameworks for metal–air electrochemical systems. The carbon GDE frameworks were produced by electrospinning. It was found that the motion of ionic liquids in the highly porous hosts is more complex than what is commonly exhibited by conventional fluids, which makes a multimodal investigation essential for an adequate description of mobility and wetting of GDEs. Observed NMR diffraction-like patterns cannot be linked to the tortuosity limit but may serve as a proxy for structural features in the fibrous material. While the observed data were interpreted using standard theoretical models, alternative explanations and causes for artifacts are discussed.

Here we investigate the organic ionic plastic crystal (OIPC) 1,2-bis[N-(N\'-hexylimidazolium-d2(4,5))]C2H4 2PF6- in one of its solid plastic crystal phases by means of multi-nuclear solid-state (SS) NMR and pulsed-field-gradient (PFG) NMR. We quantify distinct cation and anion diffusion coefficients as well as the diffusion activation energies (Ea) in this dicationic imidazolium-based OIPC. Our studies suggest a change in transport mechanism for the cation upon varying thermal and magnetic treatment (9.4 T), evidenced by changes in cation and anion Ea. Moreover, variable temperature 2H SSNMR lineshapes further support a change in local molecular environment upon slow cooling in B0. Additionally, we quantify the percentage of mobile anions as a function of temperature from variable temperature 19F SSNMR, where two distinct spectral features are present. We also comment on the pre-exponential factor (D0), giving insight into the number of degrees of freedom for both cation and anion as a function of thermal treatment. In conjunction with previously reported conductivity values for this class of OIPCs and the Stokes-Einstein relation, we propose that ion conduction is dominated by anion diffusion between crystallites (i.e., grain boundaries). Using our experimentally determine diffusion coefficient and previously reported PF6- hydrodynamic radius (rH), viscous (" = 4.1 Pa " s) ionic liquid (IL) is present with a cation rH of 0.34 nm. NMR measurements are very powerful in elucidating fundamental OIPC properties and allow a deeper understanding of ion transport within such materials. / Master of Science

The main subject of this thesis is the synthesis and investigation of the properties and potential applications of a new class of hybrid compounds consisting of a rigid, electroactive 4,4’-bipyridinium core capped by nucleobase terminal groups with hydrogen bonding abilities. A new series of small molecules consisting in a 4,4’-bipyridinium unit carrying thymine or/and adenine as capping groups was synthetized. The synthesis strategy implied the regioselective alkylation of thymine and adenine bases respectively, followed by coupling of the alkylated precursors to 4,4’-bipyridine unit via Menschutkin reaction. Electrochemical, spectroelectrochemical and optical investigations revealed an intramolecular charge transfer (CT) relationship between nucleobases as donors and 4,4’-bipyridinium unit as acceptor which is accompanied by a change in color and a shift of the reduction potentials (approx. 60 mV). The viologen-nucleobase derivatives, particularly viologens capped by thymine, were used as building blocks to create self-assembled functional nanostructures in the presence of complementary templates such as oligonucleotides or ssPNA analogues via thymine-adenine interactions. The viologen-thymine derivatives were found to partially precipitate oligonucleotides or plasmid DNA by mean of coulombic interactions and form stable polyplexes that could be used as potential gene delivery vectors. It was found that the number of positive charges, as well as the number of thymine units per viologen-thymine derivative determines whether the interaction with DNA is dominated by electrostatic or by hydrogen bonding interactions. New electroactive ionic liquid crystals were prepared by ion pairing of viologen-nucleobase dicationic species with amphiphilic 3,4,5-tris(dodecyloxy)benzene sulfonate anion. The nucleobases with ability to self-associate by hydrogen bonding were found to influence not just the thermotropic behavior, by decreasing transition temperature from crystalline to mesophase state, but also the supramolecular arrangement in solution. A versatile approach to functionalize mesoporous TiO2 film with viologen-nucleobase derivatives was developed consisting of hydrogen bonding layer-by-layer deposition of viologen-nucleobase derivatives on TiO2 surface using the thymine-adenine molecular recognition as driving force for immobilization. This method is promising and represents an easy way to construct optoelectronic device components as was demonstrated with the construction of a switchable electrochromic device.

Asymmetries in physisorbed systems give rise to interesting phases and phase transitions in two-dimensional (2D) monolayer and multilayer systems. The effects of asymmetric adsorbate and substrate interactions in monolayers of dipolar molecules on ionic substrates and N2 on graphite are studied. In the case of dipolar molecules on ionic substrates, 2D dielectric phase transitions using a modified Blume-Emery-Griffiths (BEG) model are determined theoretically. A dipole adsorbed vertically above a metal ion lattice site, and pointing up (down), is assigned a spin s=+1 (s=-1). An empty lattice site is assigned a spin S=0. Analytic solutions for both ferroelectrically and antiferroelectrically ordered systems are found. The model is applied to CO adsorbed on MgO and NaCl, and preliminary results for the phase diagram of CH3F on NaCl, are presented. Multilayer phase transitions for N2 on graphite are studied experimentally using synchrotron x-ray diffraction. The system is measured to undergo layering transitions, where the number of layers increases as the temperature of the system increases. A new multilayer phase diagram based on our results and the combined results published by other researchers is presented. The effects of capillary condensation on this multilayer system are quantified, and it is determined that its primary effect is to broaden the discrete layering transitions. The results for both studies are put into context with other adsorption systems with asymmetric interactions.

L’utilisation de la biomasse végétale, que ce soit à des fins énergétiques, papetières ou valorisation dans le domaine des biomatériaux via des filières de biorafineries, nécessite la séparation des différents copolymères qui la composent par des méthodes physique et/ou chimique. Par exemple, les méthodes classiques utilisées pour extraire la cellulose mettent en jeu des réactions acido-basiques et provoquent des modifications de la structure des lignines à cause des réactions de recondensation, de déalkylation et de déshydratation. L’exploitation des lignines dans le domaine des matériaux est limitée par plusieurs facteurs notamment leur faible solubilité dans les solvants usuels, leur poids moléculaire élevé et leur faible nombre de phénols libres à l’origine de leur réactivité chimique. Ce projet s’inscrit dans un contexte de valorisation des lignines industrielles en tenant compte la structure chimique spécifique de chaque type de lignine Son objectif consiste à développer de nouvelles stratégies permettant la rupture des liaisons les plus labiles sur la chaine propyle des sous unités phénylpropanoïdes puis leur fonctionnalisation en optimisant la formation d’éthers d’énols ou en permettant leur rupture directe en évitant au maximum les réactions de recondensation en utilisant les liquides ioniques comme milieu réactionnel. Un focus particulier sera fait sur la fonctionnalisation possible des éthers d’énols conduisant à une dépolymérisation sélective des lignines papetières qui en contiennent un taux non négligeable. Selon les lignines industrielles, ces méthodes devraient permettre d’obtenir des oligomères de plus faible masse, d’augmenter également la fraction phénolique et d’améliorer la solubilité des lignines transformées ainsi que leurs propriétés antioxydantes. / The ability to use plant biomass in energy, paper industry or valorization in the field of biomaterials via biorefineries, requires the separation of the various copolymers by physical or chemical methods. For exemple, the classic methods used to extract the cellulose involve acido-basic reactions and cause modifications of the structure of lignins because of recondensation, dealkylation and dehydration reactions. The exploitation of lignins in the field of materials is limited by several factors as their low solubility in usual solvents, their high molecular weight and low number of free phenol fonctions. This project joins in a context of valuation of the industrial lignins by taking into account the specific chemical structure of every type of lignin. Its obvective consists in developing new strategies to cleave weak bonds on the propyl chain of phenylpropan units, then their fonctionnalization by optimizing the formation of enol ethers or their direct cleavage by avoiding the reactions of recondensation by using ionic liquids as reaction medium. A particular focus will be made on the possible fonctionnalization of enol ethers for a selective depolymerization of industrial lignins who contain a not insignificant rate. According to the structur of lignins, these methods should allow to obtain oligomers with low molecular weight, to increase also the phenolic fraction and improve the solubility of the transformed lignins as well as their antioxidant properties.

Afin de proposer une alternative aux supercondensateurs utilisant des électrolytes aqueux sous forme liquide produits par la société Hutchinson, ces travaux de thèse ont porté sur le développement de gels ioniques, composés de polymères réticulés gonflés par un liquide ionique, pouvant être utilisés comme électrolytes. L’objectif est donc ici de synthétiser des membranes auto-supportée, de faible épaisseur (e = 100 µm) et de haute conductivité ionique. Les deux premières stratégies de synthèse, basé respectivement sur la préparation de réseaux de poly(1,2,3-triazolium)s et sur la réticulation de copolysiloxanes, n’ayant pas permis d’obtenir de matériaux avec des propriétés satisfaisantes, des films de polyacrylates contenant des liquides ioniques imidazoliums ont été développés. Grâce à l’insertion de hauts taux de cette phase liquide à l’intérieur de ces ionogels, jusqu’à 70 w%, des conductivités supérieures à 10-3 S cm-1 à 30°C ont pu être atteintes, tout en gardant une bonne tenue mécanique à faible épaisseur. Ces électrolytes ont pu être caractérisés électrochimiquement et ont démontré qu’ils permettaient de préparer des cellules supercapacitives fonctionnelles. Cependant, les faibles capacités obtenues indiquent un faible remplissage de la porosité des électrodes, qui est limitant pour l’échange des charges. La poursuite de ces travaux est donc nécessaire pour optimiser ces matériaux, ainsi que les montages utilisés, mais ces gels s’avèrent malgré tout prometteurs et ont pu permettre de préparer des cellules de dimensions équivalentes aux systèmes commerciaux / In order to offer an alternative to the supercapacitors based on aqueous liquid electrolytes that are produced by Hutchinson, this thesis has focused on the development of ionic gels composed of crosslinked polymers containing an ionic liquid phase, that can be used as electrolytes. So, the goal of this study has been to synthesize self-supported thin films (e = 100 µm) with high ionic conductivity.The first two synthesis strategies, respectively based on poly(1,2,3-triazolium)s networks and the crosslinking of polysiloxanes copolymers, did not lead to materials with satisfying properties for this application. So, a third synthesis pathway, based on the copolymerization of acrylate monomers in the presence of imidazolium ionic liquids was developed. As these ionogels were able to contain as much as 70 w% of this liquid phase, ionic conductivities of up to 10-3 S cm-1 at 30°C were obtained, while maintaining good mechanical stability at very low thickness. These electrolytes were characterized by electrochemical measures, and displayed the ability to function inside supercapacitive cells. However, low specific capacities were obtained, indicating that the electrodes’ porosity is only partially filled. Further work is necessary for the optimization of these ionogels, as well as the adaptation of the cells’ components, but these materials showed good potential nevertheless, as they allowed the preparation of functioning cells with the same dimensions as commercial devices

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第17888号 / 工博第3797号 / 新制||工||1581(附属図書館) / 30708 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 田中 功, 教授 酒井 明, 教授 邑瀬 邦明 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18278号 / 工博第3870号 / 新制||工||1594(附属図書館) / 31136 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 田中 功, 教授 邑瀬 邦明, 教授 酒井 明 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18983号 / 工博第4025号 / 新制||工||1620(附属図書館) / 31934 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 田中 功, 教授 宇田 哲也, 教授 白井 泰治 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19011号 / 工博第4053号 / 新制||工||1624(附属図書館) / 31962 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 赤木 和夫, 教授 秋吉 一成, 教授 金谷 利治 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM