Orientador: Fabio Augusto / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-27T10:01:00Z (GMT). No. of bitstreams: 1 Sampaio_BrunaReginadeToledo_M.pdf: 17858649 bytes, checksum: c23714f1f5bd4e3d6e831f6705306053 (MD5) Previous issue date: 2015 / Resumo: Nesta dissertação é descrita duas novas abordagens para microextração em fase sólida. A primeira delas tem como objetivo aumentar a massa extraída já que a mesma é limitada pelo reduzido volume da fase extratora. Para isso, foi proposto o desenvolvimento de um dispositivo, no qual ocorre a compartimentalização do processo de dessorção dos analitos da matriz e a sorção dos mesmos pela fibra de SPME. Dessa forma é possível operar simultaneamente nas temperaturas ótimas de cada processo. O processo de extração ocorre no modo headspace dinâmico, no qual um gás de purga é percolado pela matriz, tornando-se saturado pelos analitos. Este gás transporta os analitos para o interior do dispositivo onde os mesmos serão extraídos pela fibra de SPME resfriada. Esse resfriamento é necessário pois a sorção do analitos pela fibra é um processo exotérmico. Já a segunda abordagem propõe a confecção de novas fibras sortivas baseadas em polímeros iônicos líquidos com o intuito de expandir a aplicabilidade da SPME pois comercialmente, a quantidade de fibras disponíveis é bastante limitada, principalmente no que se refere à extração de analitos polares. Nesta abordagem foi possível a criação de uma nova rota para confecção de fibras baseadas em polímeros iônicos líquidos empregando-se nitinol como suporte, o que promoveu maior resistência e durabilidade para a fibra. Estas novas fibras apresentaram precisões com valores de desvio padrão relativo em torno de 15% e robustez em condições severas de extração; tais fibras foram aplicadas, para prova de conceito, em um estudo de detecção e quantificação de adulteração em café / Abstract: This thesis describes two new approaches to solid-phase microextraction (SPME). The first aims to increase the extracted mass since, which is limited by the small volume of the extraction phase. In this context, it is proposed the development of a device that compartmentalizes the desorption of the analytes from the matrix to the headspace and their sorption by the SPME fiber. This setup allows the simultaneous operation of each process at their optimum temperatures. The extraction process takes place in the dynamic headspace where a inert purge gas is percolated through sample matrix, becoming saturated with the analytes. This gas, then, transports the analytes to the device where they will be sorbet by cold SPME fiber. This cooling is necessary since the sorption of analytes by the fiber is an exothermic process. The second approach proposes the development of new sorbent coatings based on polymeric ionic liquids. It was possible to create a new route for manufacturing nitinol-based SPME fibers coated with PIL providing greater strength and durability of the fiber. These new fibers showed precision with relative standard deviations below 15% and robustness in harsh conditions of extraction / Mestrado / Quimica Analitica / Mestre em Química

This thesis deals with ionic liquids and use of ionic liquids as electrolytes in lithium-ion batteries. Thesis describes basic characteristics of secondary electrochemical cells and characteristics of ionic liquids. Thesis also describes modifications and measurement of ionic liquids. Thesis also presents the results of measurement conductivity and potential window of modified ionic liquids.

Dans le but d’améliorer les performances des micro-accumulateurs au lithium, de nouvelles voies de dépôt, compatibles avec des géométries texturées, sont actuellement explorées. Au cours de ce travail de thèse, un nouvel électrolyte solide déposé par voie « humide » a été développé. Ce matériau, composé d’un liquide ionique et d’un sel de lithium confinés dans une matrice solide, a été synthétisé par polymérisation in-situ d’un oligomère diméthacrylate. Afin de définir leurs caractéristiques de conduction ionique, de nouvelles méthodes, comme le suivi de la photo-polymérisation par impédance in-situ ou encore la réalisation d’un nouveau design de cellules à base de peignes interdigités, ont été développées. De plus, le transfert du lithium a été mesuré par RMN diffusionnelle. Une diminution significative de la vitesse de diffusion des ions Li+ après la photo-polymérisation a ainsi été mise en évidence. La spectroscopie Raman a permis de démontrer que celle-ci est due à la complexation des ions par les chaines de poly(oxyde d’éthylène) de la matrice solide. En outre, grâce aux observations de différentes compositions, un mécanisme de diffusion mixte des ions Li+ par migration dans le liquide et par sauts dans le solide a été identifié. Par conséquent, ces résultats nous ont permis de définir une stratégie pour améliorer la diffusion des ions Li+ : l’ajout d’un copolymère monofonctionnel a permis de diminuer la densité de réticulation de la matrice solide et ainsi d’optimiser la mobilité des chaines polymères. En effet, les performances de cyclage dans des empilements de micro-accumulateurs complets ont été améliorées. A température ambiante, ces résultats se sont révélés très proches de ceux obtenus avec l’électrolyte solide standard LiPON. En conclusion, l’analyse établie a permis de comprendre les liens entre structure et performances électrochimiques, ce qui a permis de dégager les voies d’amélioration les plus prometteuses pour ce type d’électrolytes. / New deposition techniques compatible with making tridimensional geometries are currently being investigated with the aim of improving the performances of lithium microbatteries. This work focuses on the development of a new quasi-solid electrolyte deposited by a “wet process”. An ionic liquid-based membrane containing a lithium salt was prepared by the photo-induced polymerization of a dimethacrylate oligomer. New methods such as a new type of conductivity cell based on planar interdigitated electrodes to measure ionic conductivity as well as in-situ monitoring of photo-polymerization using impedance spectroscopy were used. Transport properties of lithium ion were measured by PGSE-NMR. Interestingly, a significant reduction of lithium ion mobility was observed after UV-curing while the total ionic conductivity only decreased slightly. This phenomenon is due to the formation of lithium ion complexes with ethylene oxide moieties of the solid matrix, evidenced by Raman spectroscopy measurements. Additionally, we have shown that the structures of the complexes depend on the salt concentration and a dual solid/liquid transport mechanism was suggested. Hence, in order to improve lithium ion diffusion, a co-polymer was added in an attempt to decrease the cross-linking density of the solid matrix thus improving its segmental motion. The cyclability of the all solid state micro batteries was indeed improved. Comparable performances with the standard solid electrolyte LiPON were obtained at room temperature. In summary, it was established that electrochemical performances of the solid state microbatteries depend to a certain extent on the structure of the polymer electrolyte. Therefore it is possible to find new ways in designing these types of electrolytes for further improvement.

Metals, essential constituents of a vast number of products and industrial processes, are paradoxically confronted to a scarcity issue without precedents. Among the emerging technologies for sustainable metal recovery, bio-electrochemical systems (BES) stand at a research state with a potential application on low-content metal streams. They are based on electroactive bacteria that can exchange electrons with their environment to drive an (electro)chemical metal precipitation. The feasibility of three configurations of BES aiming to recover metals at low-energy and low-chemicals consumption was explored. A first approach inspired on metal-bacteria interactions aimed to transform gold and chromium ions into added-value products. A polarized cathode promoting the metal reduction and symbiotically producing metallic nanoparticles on bacteria was studied. A second configuration used a halophilic bioanode to recover a panel of metals including transition metals and rare earth elements from marine environments. Metals were not directly precipitated by the contact with bacteria, but via a gas-diffusion cathode coupled to the bioanode. The third configuration considered a neodymium electrochemical reduction coupled to an oxidation catalyzed by a bioanode. Here, the conventional metal-containing aqueous system was replaced by an ionic liquid, an emerging solvent suitable for REE electrodeposition. / Les métaux, composants essentiels d'un grand nombre de produits et de processus industriels, sont paradoxalement confrontés à un problème de pénurie sans précédent. Parmi les technologies émergentes pour la récupération durable des métaux, les systèmes bio-électrochimiques (BES) sont à la recherche d’une application potentielle sur des matrices aqueuses de métaux à faible teneur. Ils sont basés sur des bactéries dites électro-actives, pouvant échanger des électrons avec leur environnement afin de conduire une précipitation de (électro)chimique du métal. Le but étant d’explorer différents procédés de récupération de métaux à faible consommation d'énergie et de produits chimiques, trois configurations de BES ont été abordés. Une première approche inspirée des interactions métal-bactérie visait à transformer les ions d’or et de chrome en produits à valeur ajoutée. Une cathode polarisée favorisant la réduction des métaux et produisant de manière symbiotique des nanoparticules métalliques sur des bactéries a été étudiée. Une seconde configuration utilisait une bioanode halophile pour récupérer un panel de métaux comprenant des métaux de transition et des éléments de terres rares provenant d’environnements marins. Les métaux ne sont pas précipités directement par le contact avec les bactéries mais par une cathode à diffusion gazeuse couplée à la bioanode. La troisième configuration envisageait une réduction électrochimique au néodyme couplée à une oxydation catalysée par une bioanode. Le système aqueux contenant un métal conventionnel a été remplacé par un liquide ionique, un solvant émergent avantageux pour l'électrodéposition de terres rares.

Title: Cellulose dissolution: Comparison of two non-derivatizing solvent systems and the effect of additives Author: Nikolay Kotov Institute: Institute of Macromolecular Chemistry, Czech Academy of Sciences Supervisor of the doctoral thesis: RNDr. Jiří Dybal, CSc. Consultant: Mgr. Adriana Šturcová, Ph.D. Institute of Macromolecular Chemistry, Czech Academy of Sciences, Department of Vibrational Spectroscopy Abstract: Cellulose is an abundant renewable material, which processing and applicability is limited owing to cellulose inability to dissolve in commonly used solvents. Only specific solvents or their combinations are able to dissolve cellulose and its dissolution processes remain unclear till nowadays. Aim of this thesis was to acquire new experimental information on the changes which cellulose exhibits upon dissolution in two exemplary solvents: an ionic liquid 1-butyl-3-methylimidazolium chloride (bmimCl) and in an organic solvent N,N-dimethylacetamide (DMAc) with lithium chloride (LiCl). The main tool for that investigation is vibrational spectroscopy which provides valuable information about the polymer structure. Similarities and differences found in the spectra of cellulose in those two solvents and influence of cellulose on the solvents are analyzed. Furthermore, influence of additives on the...

Esta tesis es un estudio profundo de las propiedades interfaciales Metal|líquido iónico (LI), y como estas influyen en las primeras etapas de formación de electrodepósito metálico. Dos líquidos iónicos, de dos familias diferentes, se han escogido para el análisis: un Room Temperature Ionic Liquid (RTIL): [Emmim][Tf2N]; y un Deep Eutectic Solvent (DES): 1ChCl:2urea. Para estudiar la influencia superficial en los distintos procesos, se empleó monocristales de platino (Pt(111)) y de oro Au(hkl), principalmente. El análisis inicial de las propiedades interfaciales M(hkl)|LI se realizó utilizando, entre otras técnicas, la técnica de salto de temperatura con láser pulsante, técnica que además permitió estimar el valor de potencial de carga (valor característico de la interfase metal|electrolito) en cada caso. Una vez caracterizados electroquímicamente estos sistemas, ambos LIs se utilizaron para estudiar el depósito metálico en distintas superficies tanto orientadas como poliorientadas. En concreto, se investigó el depósito de Ag y Cu en DES y sobre carbono vítreo, obteniendo que el DES influenciaba el mecanismo de nucleación y crecimiento y permitía modular el tamaño de grano. Se analizó la formación de ad-capas UPD de Cu en Au(hkl) y en DES, observándose dependencia del proceso con la orientación del sustrato y el tipo de electrolito. Finalmente, se evaluó la aplicabilidad de estos dos solventes para modificar un sustrato orientado de platino (Pt(111)) con Ni, y la sensibilidad superficial del proceso, para ello combinando técnicas clásicas como voltametría cíclica y cronoamperometría con técnicas ex-situ como SEM y AFM (para recubrimientos de baja cobertura). El presente trabajo doctoral muestra el potencial de estos solventes para modificar una superficie con distinto metales y de forma sencilla, a través de la técnica formación de depósito electroquímico, abriendo la posibilidad de utilizar estos novedosos solventes para el diseño de nuevos materiales.

Les recherches sur des attogrammes (1 attogramme = 10 -18 gramme) et zeptogrammes (1 zeptogramme = 10-21 gramme) de matière offrent la possibilité de mettre en évidence la transition entre la nanoscience et la physique des molécules, ouvrant la porte à des questions fondamentales en physique de la matière molle, comme par exemple ‘’Quelle est la quantité minimale de matière nécessaire pour ‘‘définir’’ les propriétés des matériaux ?’’. Les propriétés électriques et diélectriques des matériaux, à cette échelle, sont étudiées par la spectroscopie diélectrique. Cette technique offre une large gamme de fréquence, pour mesurer les propriétés diélectriques des matériaux, couvrant plus de 10 ordres de grandeur et allant de 10-3 à 10+7 Hz. Cette technique assure une caractérisation précise d’une grande diversité des phénomènes physiques qui se déroulent à des échelles de longueur et de temps différents, tels que: les transitions des phases, les fluctuations de densité, les fluctuations moléculaires, le transport des charges, etc. Les mesures à l’échelle des attogrammes et zeptogrammes nécessitent l’utilisation des cellules ayant des dimensions nanométriques. Basé sur le concept d’utiliser des nano-conteneurs comme des cellules expérimentales, un développement expérimental a été mis en évidence, dans cette thèse, permettant d’étudier la dynamique moléculaire et les transitions des phases des matériaux polymères, allant jusqu’au zeptogrammes de matière. Cette approche permet de cristalliser des très petites quantités des matériaux sous l’application d’un champ électrique élevé, dans le but d’induire une cohérence macroscopique des fonctions moléculaires. Cela peut donner lieu à des nouvelles propriétés des matériaux, qui n’existent pas dans le cas des matériaux en masse / Dielectric investigations on attograms (1 attogram = 10 -18 gram) and zeptograms of matter (1 zeptogram = 10 -21 gram) offer the possibility of exploring the transition between nanoscience and molecule physics, opening the door for fundamental questions in soft-matter physics, such as for instance “What is the minimum amount of matter necessary to “define” the material properties?”. The electric and dielectric properties of materials at this level are investigated by Broadband Dielectric Spectroscopy. This technique provides an extraordinary broad frequency range, for measuring dielectric properties of matter, covering more than 10 orders of magnitude, typically from 10-3 to 10+7Hz. It ensures a precise characterization of large diversity of physical phenomena taking place at different length and time scales such as: phase transitions, density fluctuations, molecular fluctuations, charge transport processes, etc. Measurements on the scale of attograms and zeptograms require sample cells having all three dimensions on the nanometric length-scale. Based on the concept of employing nanocontainers as experimental cells, a novel experimental development allowing investigations on molecular dynamics and phase transitions of polymeric materials down to the level of zeptograms is demonstrated in the present PhD study. This approach enables one to crystallize tiny amounts of matter under high electric fields with the goal of inducing a macroscopic coherence of molecular functionalities. This could give rise to new material properties, not naturally available in the case of bulk materials.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第18607号 / エネ博第303号 / 新制||エネ||62(附属図書館) / 31507 / 京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻 / (主査)教授 萩原 理加, 教授 佐川 尚, 教授 平藤 哲司 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

No description available.

Mass spectrometry (MS) has become a widely used technique for the characterization of a wide range of substances in diverse fields. The selection of appropriate ionization techniques, source parameters, charge carriers based on the analyte’s polarity is essential in MS as only the ions are detected. When using a soft ionization technique, single stage-MS at best provides only chemical composition; thus, tandem MS is needed to determine structural information and dissociation pathways. This dissertation focuses on the characterization of various small molecules and ions using different ionization techniques, charge carriers, and collision-induced dissociation (CID). In Chapter II, commercially available ionic liquid (IL) cations, specifically imidazolium-based IL cations with different side-chain chemistries, were characterized by CID-MS. The imidazolium-based IL cations have diverse dissociations pathways depending on the nature of the side chain (aliphatic or aromatic) or the functional groups (allyl, vinyl, alcohol, methoxy, nitro) present on the side chain. Additionally, it was observed that some IL cations undergo thermal degradation under normal operating temperatures of electrospray ~275 °C. A variety of experimental and complementary computational chemistry results are presented. In Chapter III, cis-3-hydroxyproline (c3hPro) and cis-4-hydroxyproline (c4hPro) isomers were differentiated upon lithiation using CID-MS. The CID-MS of [c4hPro+Li]+ produces three primary fragmentation pathways, namely the neutral losses of H2O, CO, and CO2; whereas CID-MS of [c3hPro+Li]+ produces only loss of CO2 in this same region. These observations may have analytical utility, and in this work, the experimental observations were explored with thermodynamic and transition state calculations to better understand the processes. In Chapter IV, the accurate mass of synthetic monomers including PAH perfluorocycloalkene monomers and their precursors were measured and reported with a publication-quality mass accuracy using atmospheric pressure chemical ionization (APCI)-MS. Additionally, the effect of solution flow rate, ionization mode, source parameters (such as vaporization temperature, dry gas temperature and dry gas flow rate, nebulizer gas pressure), acidification, and different solvent systems on APCI-MS signal intensity were studied.