abstract: The field of Ionic Liquid (IL) research has received considerable attention during the past decade. Unique physicochemical properties of these low melting salts have made them very promising for applications in a many areas of science and technology such as electrolyte research, green chemistry and electrodeposition. One of the most important parameters dictating their physicochemical behavior is the basicity of their anion. Using four sets of Protic Ionic Liquids (PILs) and spectroscopic characterization of them, a qualitative order for anion basicity of ILs is obtained. Protic Ionic Liquids are made by proton transfer form a Brønsted acid to a base. The extent of this transfer is determined by the free energy change of the proton transfer process. For the cases with large enough free energy change during the process, the result is a fully ionic material whereas if the proton transfer is not complete, a mixture of ions, neutral molecules and aggregates is resulted. NMR and IR spectroscopies along with electrochemical and mechanical characterization of four sets of PILs are used to study the degree of ionicity. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2016

Yes / Ionic liquids (ILs) are key materials for the development of a wide range of emerging technologies. Protic ionic liquids, an important class of ILs, have long been envisioned as promising anhydrous electrolytes for fuel cells. It is well known that in comparison to all other cations, protons exhibit abnormally high conductivity in water. Such superprotonic dynamics was expected in protic ionic conductors as well. However, many years of extensive studies led to the disappointing conclusion that this is not the case and most protic ionic liquids display subionic behavior. Therefore, the relatively low conductivity seems to be the main obstacle for the application of protic ionic liquids in fuel cells. Using dielectric spectroscopy, herein we report the observation of highly decoupled conductivity in a newly synthesized protic ionic conductor. We show that its proton transport is strongly decoupled from the structural relaxation, in terms of both temperature dependence and characteristic rates. This finding offers a fresh look on the charge transport mechanism in PILs and also provides new ideas for design of anhydrous materials with exceptionally high proton conductivity. / National Science Centre within the framework of the Opus project (Grant No. DEC 2011/03/B/ST3/02072). Financial assistance from FNP START. The LDRD Program of ORNL, managed by UT-Battelle, LLC, for the U.S. DOE. Support from the NSF under grant CHE-1213444.

Les travaux réalisés dans le cadre de cette thèse ont porté sur la réalisation de polymères conducteurs de type polyaniline et de leurs composites associés à du graphène en vue d’une utilisation en tant que matériaux d’électrodes dans des dispositifs de stockage d’énergie de type supercondensateurs. Les travaux se sont tout d’abord orientés sur la synthèse de nouveaux liquides ioniques protiques (LIP) associant des cations pyrrolidinium (Pyrr+) et imidazolium (Imi+) avec des anions p-toluène sulfonate (PTS-), hydrogénosulfate (HSO4-) ou (+)-camphre-10-sulfonate (Cs-), et de l’étude de leur propriétés physico-chimiques (conductivité, viscosité) dans des mélanges binaires LIP/eau. Après avoir déterminé les formulations permettant d’atteindre les propriétés de transport optimales, les capacitances spécifiques de la Pani/HCl dans ces milieux LIP ont été déterminées et nous avons montré que les performances de dispositifs symétriques sont améliorées en capacitance, énergie et en puissance (400 F/g, 7 Wh.kg-1 et 4 kW.kg-1 pour les valeurs les plus élevées) par rapport à un milieu H2SO4 1M. Ces milieux LIP ont également été utilisés comme milieu de synthèse de la Pani. Nous avons ainsi montré que la nature des LIP, qui sont des milieux nanostructurants, pouvait modifier les propriétés électroniques, morphologiques et thermiques des Pani. Un optimum de conductivité électronique de la Pani (22 S/cm) a été atteint avec une synthèse réalisée dans le mélange binaire [Imi][HSO4]/eau 70/30 (pourcentage massique) générant une morphologie fibrillaire et une bonne cyclabilité (93% de rétention de capacitance sur 1000 cycles dans H2SO4 1M. Des valeurs de près de 400 F/g ont été obtenues dans le mélange [Pyrr][HSO4]/eau 41/59 optimisé. Dans le cas de la synthèse de la Pani réalisée dans [Pyrr][PTS]/eau, un gain en stabilité thermique (360°C) est obtenu grâce au dopage par l’anion PTS-. Finalement, une étude exploratoire sur la préparation de composites Pani/graphène et Pani/oxyde de graphène a été réalisée. Les synthèses des nanocomposites ont été effectuées dans les mélanges LIP/eau. L’optimisation de la composition du composite a été étudiée et indique que des rapports massiques de graphène ou oxyde de graphène d’environ 15% permettent d’atteindre des performances de stockage prometteuses et exaltées par rapport à celles obtenues pour des Pani sans graphène. / The work carried out during this PhD thesis is based on the preparation of conducting polymers such as polyaniline (Pani) and their composites associated with graphene for use as electrode materials for supercapacitors application. This work was first dedicated to the synthesis of new protic ionic liquids (PILs) combining pyrrolidinium (Pyrr+) or imidazolium (Imi+) cations with p-toluene sulfonate (PTS-), hydrogen sulfate (HSO4-) or (+)-camphor-10-sulfonate (Cs-) anion, and the study of their physico-chemicals properties (conductivity, viscosity) in binary mixtures PILs/water. After determining the formulations needed to achieve the optimum of transport properties, the specific capacitance of Pani/HCl in these PILs medium was determined, and we have shown that the performance of symmetrical devices are improved in capacitance, specific energy and specific power (400F/g, 7Wh/kg and 4kW/kg for the higher values) in comparison to those obtained in a H2SO4 1M medium. These PILs mediums were also used as a synthesis medium of Pani. We have shown that the nature of PILs, acting as soft template, could change the electronic, morphological and thermal properties of Pani. An optimum of electronic conductivity of Pani (22 S/cm) was obtained with a synthesis realized in the binary mixture [Imi][HSO4]/water 70/30 generating a fibrillar morphology and a good cyclability (93% capacitance retention over 1000 cycles in H2SO4 1M at 2 A/g). For Pani synthesis in [Pyrr][PTS]/water, a thermal stability gain (360 °C) is obtained thanks to a PTS- doped Pani. Finally, a preliminary study on the preparation of composite Pani/graphene and Pani/graphene oxide was performed. The syntheses of nanocomposites were realized in PILs/water mixtures. The optimization of the composition of the Pani nanocomposites was studied and it was found that a mass ratio of about 15% in weight of graphene or graphene oxide enables to obtain promising nanomaterials with higher electrochemical performances compared with pristine Pani.

Submitted by infopei ufba (infopei@ufba.br) on 2017-05-09T19:46:25Z No. of bitstreams: 1 GICELIA_ANTONIA_FERREIRA.pdf: 3057739 bytes, checksum: b093d440c933d9b788d39cd5ae0fd117 (MD5) / Approved for entry into archive by Flávia Sousa (flaviabs@ufba.br) on 2017-05-29T18:50:20Z (GMT) No. of bitstreams: 1 GICELIA_ANTONIA_FERREIRA.pdf: 3057739 bytes, checksum: b093d440c933d9b788d39cd5ae0fd117 (MD5) / Made available in DSpace on 2017-05-29T18:50:20Z (GMT). No. of bitstreams: 1 GICELIA_ANTONIA_FERREIRA.pdf: 3057739 bytes, checksum: b093d440c933d9b788d39cd5ae0fd117 (MD5) / CAPES, FAPESB / Nos dias atuais, há um grande e crescente interesse em encontrar substâncias ambientalmente amigáveis para processos industriais. Os líquidos iônicos são candidatos a substituir os solventes orgânicos convencionais reduzindo a quantidade de resíduos e diminuindo o impacto ambiental; à temperatura ambiente, esses materiais praticamente não possuem pressão de vapor, são não inflamáveis, podendo ser sintetizados de modo específico, através da combinação diferencial entre cátions e ânions, para desempenhar o papel necessário, além de serem facilmente recicláveis. Os líquidos iônicos são novos meios promissores para muitos processos, tais como síntese química, reações enzimáticas e aplicações no setor de “engenharia verde”. O interesse pela classe dos líquidos iônicos próticos justifica-se em decorrência da sua síntese simples, do baixo custo produção, da baixa toxicidade e da biodegradabilidade, os quais são aspectos inerentes aos processos “verdes”. Nesse contexto, ressalta-se a aplicação dos líquidos iônicos próticos na síntese enzimática de ésteres graxos de açúcares. Cumpre destacar que os mesmos podem ser sintetizados quimicamente ou enzimaticamente. A síntese química diverge da tendência atual, na qual o foco está voltado para a utilização de tecnologias sustentáveis e ambientalmente seguras. Por outro lado, a síntese enzimática é realizada em condições mais suaves de reação, apresenta elevada seletividade e especificidade, o que facilita a recuperação do produto. Porém, a síntese enzimática de ésteres graxos de açúcares encontra um obstáculo, uma vez que os solventes orgânicos capazes de solubilizar adequadamente os carboidratos também agem de forma negativa sobre as enzimas, inativando-as. Portanto, no presente trabalho foi investigado um conjunto de líquidos iônicos próticos visando identificar um meio de reação apropriado para o processo enzimático de síntese do oleato de galactose, que atenda às condições de maximizar a solubilização do carboidrato. Para tanto, uma gama de líquidos iônicos próticos foram sintetizados e caracterizados em termos de coeficiente de partição, viscosidade e solubilidade da galactose, pois essas propriedades exercem influência direta sobre a ação enzimática. Até o melhor de nosso conhecimento, este é o primeiro estudo com foco no processo de produção enzimática de ésteres graxos de açúcares na presença de líquidos iônicos próticos. / Nowadays, there is a great and growing interest in environmentally friendly substances for industrial processes. Ionic liquids are candidates to replace the conventional organic solvents decreasing the amount of waste and reducing the environmental impact; at room temperature, ionic liquids have practically no vapor pressure, are not flammable and may be synthesized specifically through the differential combination of cations and anions, in order to perform the role needed, and are easily recyclable. Ionic liquids are new promising media for many processes, such as chemical synthesis, enzymatic reactions and applications in the “green engineering” sector. The interest for the class of protic ionic liquids is justified due to their simple synthesis, low cost of production, low toxicity and biodegradability potential, which are aspects inherent to the “green” processes. In this context, we highlight the application of protic ionic liquids in the enzymatic synthesis of fatty esters of sugars. It is worth noting that the same can be synthesized chemically or enzymatically. The chemical synthesis diverges from the current trend, in which the focus has turned to the use of sustainable and environmentally safe technologies. On the other hand, the enzymatic synthesis is performed under milder reaction conditions, presents high selectivity and high specificity, besides product recovery ease. Nevertheless, the enzymatic synthesis of fatty esters of sugars meets an obstacle, because the organic solvents able to adequately solubilize the carbohydrate also act negatively on the enzymes, inactivating them. Therefore, in the present study was proposed to investigate a class of protic ionic liquids in order to identify an appropriate reaction medium to the enzymatic process of synthesis of galactose oleate, which meets the conditions of maximizing the solubilization of the carbohydrate. For that, a range of protic ionic liquids were synthesized and characterized in terms of partition coefficient, viscosity and solubility of galactose, because these properties directly influence the enzymatic action. To the best of our knowledge, this is the first study focusing on the enzymatic production process of fatty esters of sugars in the presence of protic ionic liquids.