Die Kopplung von akustischer Levitation mit optischer Spektroskopie ermöglicht die Untersuchung von Reaktionen und intermolekularen Wechselwirkungen unter besonderen Bedingungen. Mit akustischer Levitation können Proben im µL-Bereich kontaktfrei gehaltert und Verunreinigungen durch Oberflächenkontaminationen ausgeschlossen werden. Durch die Verwendung verschiedener Methoden der optischen Spektroskopie wie Raman-Streuung, UV/Vis-Absorptions- und Fluoreszenz-Spektroskopie konnten die levitierten Proben untersucht werden. Die durchgeführten Untersuchungen zeigen, dass die Ultraschallfalle aufgrund der Wandlosigkeit sowie des Kontakts der levitierten Probe mit der Atmosphäre und der daraus resultierenden möglichen Aufkonzentrierung eine interessante Möglichkeit zur Probenhandhabung in der Mikrofluidik darstellt. Anhand zweier sonochemischer Reaktionen wurde mit Absorptionsspektroskopie gezeigt, dass das Ultraschallfeld des Levitators nur einen sehr geringen Einfluss auf die levitierte Probe ausübt. Mittels Absorptions- und Fluoreszenzspektroskopie wurde die durch die Verdampfung induzierte Aggregation eines Farbstoffes untersucht. Zudem wurde die relative Quantenausbeute des Farbstoffes im levitierten Tropfen bestimmt. Der Kontakt des levitierten Tropfens mit der umgebenden Atmosphäre kann auch zur Aufnahme von Substanzen aus der Atmosphäre führen. Dieser Effekt wurde anhand von levitierten ionischen Flüssigkeiten volumetrisch und schwingungsspektroskopisch bei verschiedenen Luftfeuchten untersucht und die Wechselwirkungen mit dem absorbierten Wasser detailliert charakterisiert. Die Kopplung und simultane Messung von Raman-Streuung und UV/Vis-Spektroskopie ermöglichte die Untersuchung der Bildung und Aggregation von Silber-Nanopartikeln und deren Auswirkungen auf die oberflächenverstärkte Raman-Streuung. Zudem wurde die Stabilisierung von Silber-Nanopartikeln in ionischen Flüssigkeiten und die Wechselwirkungen der Partikel mit den ionischen Flüssigkeiten untersucht. / Acoustic levitation in combination with optical spectroscopy allows for investigations of reactions and intermolecular interactions under specific conditions. Samples with microliter volumes can be handled without contact to solid surfaces resulting in the absence of impurities from surface contamination. Using different optical spectroscopy methods such as Raman, UV/vis, and fluorescence spectroscopy, different levitated samples were characterized in detail within this work. The investigations show that the acoustic levitator is an interesting tool for sample handling due to the wall-less fixture and because of the interaction of the levitated sample with the surrounding atmosphere. This interaction leads to an increase of a solved analyte upon the evaporation of the solvent. The ultrasonic field inside the trap was characterized by investigations of sonochemical reactions, which show a negligible influence of the ultrasonic field on the levitated sample. Absorption as well as fluorescence spectroscopy was used to study the aggregation of a dye due to an increasing concentration upon evaporation of the solvent. Furthermore, the relative quantum efficiency of the dye was determined from levitated droplet experiments. The interaction of the levitated droplet with the surrounding atmosphere can also lead to absorption of airborne substances. This effect was investigated for different levitated ionic liquids. Volumetric and vibrational studies were performed on levitated ionic liquids under different atmospheric humidity conditions to characterize the interaction of ionic liquids with water. Hyphenation of Raman scattering and UV/vis absorption spectroscopy enabled the investigation of the formation and aggregation of silver nanoparticles and the correlation of this information with the recorded surface-enhanced Raman spectra. In addition, the stability of silver nanoparticles in ionic liquids and the interactions of the particles with the ionic liquids were examined.

Apesar de ser utilizado há muito tempo como solvente para espécies orgânicas e inorgânicas, bem como carreador de fármacos, muitos aspectos relativos à auto-associação intermolecular do dimetil sulfóxido (DMSO) e às suas interações com espécies iônicas são ainda motivos de controvérsia na literatura. No presente estudo, a estrutura e ambiente local de dimetil sulfóxido (DMSO) em diferentes meios iônicos foram estudados por meio de três abordagens diferentes. Na primeira abordagem, o efeito de não-coincidência Raman (NCR) observado na banda atribuída ao modo ν(S=O) do DMSO, ca. 1050 cm-1, foi investigado para o líquido puro e em soluções de tetracloreto de carbono (CCl4) e água. Além disso, foi investigado o efeito de espécies iônicas (Kl, KSCN, KBr, TBAN3, TBAOCN, LiClO4, Mg(ClO4)2) na frequência ν(S=O), bem como no NCR das soluções. Os resultados de NCR juntamente com as técnicas de infravermelho, RMN e de medidas de propriedades físico-químicas mostraram que essas espécies iônicas não somente afetam a estrutura de associação do DMSO, como são capazes de interagir fortemente com o solvente. Na segunda abordagem, com a finalidade de modular as propriedades de um líquido iônico, fez-se a análise estrutural das misturas envolvendo DMSO e água como solventes e o líquido iônico EAN como soluto por meio das técnicas de espalhamento de raios-X e de nêutrons. Os resultados mostraram que a estrutura cátion-ânion do EAN é afetada pela presença de DMSO e, que em ambos os solventes são evidentes fortes ligações de hidrogênio entre o cátion EA+ e os oxigênios do solvente e do ânion nitrato. As moléculas de água não afetam drasticamente a estrutura do EAN, pois seu caráter doador/aceptor de LH e seu tamanho permite a formação de pontes entre cátion e o ânion, no entanto, EAN consegue distorcer a rede tridimensional de ligação de hidrogênio da água. Por outro lado, as moléculas de DMSO afastam os ânions da região polar do EA+ na competição pela formação de LH com o cátion e o EAN, por sua vez, provoca a ruptura das estruturas de associação do DMSO. Na terceira abordagem, misturas envolvendo três diferentes SEPs (uma classe de líquidos iônicos); Relina, MUCHCl e DMUCHCl; com DMSO foram investigadas por meio de suas propriedades físico-químicas e por espectroscopia Raman, tendo em vista modular as propriedades dos SEPs. Neste caso, os resultados não apontaram para interações fortes e específicas envolvendo as espécies iônicas e o DMSO, mas a um maior empacotamento do sistema, onde os desvios de suas propriedades físico-químicas com relação à idealidade são negativos e sua mobilidade iônica juntamente com a análise dos espectros vibracionais não evidenciaram interações específicas. No entanto, as viscosidades e densidades diminuíram nas misturas e a mobilidade iônica foi favorecida. / Although it has long been used as a solvent for organic and inorganic species, as well as drug carriers, many aspects concerning the intermolecular self-association of dimethyl sulfoxide (DMSO) and their interactions with ionic species are still controversial in the literature. In the present study, the structure and local environment of dimethyl sulfoxide (DMSO) in different ionic media were studied using three different approaches. In the first approach, the Raman non-coincidence effect (NCE) observed in the band assigned to the DMSO ν(S = O) mode, ca. 1050 cm-1, was investigated for the pure liquid and in its solutions of carbon tetrachloride (CCl4) and water. In addition, the effect of ionic species (K1, KSCN, KBr, TBAN3, TBAOCN, LiClO4, Mg (ClO4)2) on the frequency ν(S = O) as well as the NCE of the solutions were investigated. The results of NCR together with the infrared, NMR and physico-chemical properties measurements showed that these ionic species not only affect the association structure of DMSO, but are also capable of interacting strongly with the solvent. In the second approach, with the purpose of modulating the properties of an ionic liquid, the structural analysis of the mixtures involving DMSO and water as solvents and the ionic liquid EAN as a solute were carried out by X-ray and neutron scattering techniques. The results showed that the cation-anion structure of the EAN is affected by the presence of DMSO and that in both solvents strong hydrogen bonds between the EA+ cation and the oxygen from solvent and from nitrate anion are evident. The water molecules do not affect the structure of the EAN drastically, because its LH donor/acceptor character and its size allows the formation of bridges between cation and anion, however, EAN can distort the hydrogen bonding three-dimensional network in water. On the other hand, the DMSO molecules repels the anions from the polar head of EA+ in the competition in forming LH with the cation, however EAN break down DMSO association structures. In the third approach, mixtures involving three different SEPs (a class of ionic liquids); Relina, MUCHCl and DMUCHCl; with DMSO were investigated by means of their physicochemical properties and by Raman spectroscopy, in order to modulate the properties of SEPs. In this case, the results did not point to strong and specific interactions involving the ionic species and DMSO, but to a greater packaging of the system, where the deviations of its physicochemical properties with respect to the ideality are negative and its ionic mobility together with the analysis of the vibrational spectra showed no specific interactions. However, the viscosities and densities decreased in the mixtures and the ionic mobility was favored.

Este trabalho visou compreensão da solvatação em solventes puros e misturas binárias, e aplicar as informações obtidas para analisar o efeito de solventes na síntese de líquido iônico, e na dependência das propriedades de filmes de acetatos de celulose, AC, sobre o grau de substituição do éster. Para a compreensão da solvatação utilizou-se compostos (sondas solvatocrômicas) cujos espectros Uv-Vis são sensíveis às propriedades do meio. Juntamente com tais sondas, foram usadas outras duas ferramentas: (i) Modelo de solvatação preferencial; proposto por nosso grupo e que descreve a composição da camada de solvatação da sonda, considerando a existência de um \"agregado\" água - solvente orgânico. (ii)Correlações multi-paramêtricas de energia livre de solvatação; que correlacionam uma propriedade dependente do meio com as propriedades dos solventes e suas misturas. Primeiramente, estudamos a solvatação de pares de sondas que possuíam pKas semelhantes e lipofilicidades diferentes em solventes próticos. Concluiu-se que a acidez e a dipolaridade/polarizabilidade dos solventes são as propriedades mais importantes. As conclusões foram corroboradas por cálculos teóricos, que mostraram a relação entre as características estruturais da sonda e suas susceptibilidades às propriedades do meio. O mesmo conjunto de sondas foi usado no estudo de misturas água-solventes próticos. Neste, aplicou-se com sucesso o modelo de solvatação acima mencionado e, de forma inédita, conseguimos racionalizar as constantes de equilíbrio para a troca das espécies presentes (água, solvente e água-solvente) na camada de solvatação com as propriedades dos solventes puros e/ou das misturas binárias. Os resultados revelaram que a composição da camada de solvatação é regida pelas propriedades de solventes, em particular a lipofilicidade e basicidade. As sondas RB e WB foram estudadas em misturas de água com alcoóis e com solventes apróticos. O intuito era ampliar a aplicabilidade do modelo de solvatação, para o qual precisávamos conhecer o volume molar do agregado, VSolv-A, e a constante de dissociação, Kdissoc, do agregado água-solvente. Estas duas grandezas eram obtidas de forma simultânea, através de dados de densidade. Desta vez, fizemos uso de cálculos teóricos para obter, de forma independente, o volume molar e depois utilizá-lo, como parâmetro constante (não ajustável) na cálculo de Kdissoc. A comparação dos resultados mostrou que, por ambas as abordagens, o desvio entre os valores de Kdissoc era mínimo. Por outro lado, em nenhum caso a ordem de Kdissoc se alterava. Esta observação deve-se ao fato de que o cálculo simultâneo de Kdissoc e VSolv-A foi sempre baseado em número grande de dados de densidade (18) de forma que os ajustes por interação não convergissem para um falso mínimo; o nível de teoria usado nos cálculos teóricos foi adequado. Quanto às aplicações, ficou evidente como a escolha do solvente afeta a velocidade da síntese do líquido iônico. Em relação aos filmes de AC, tentamos reproduzir as propriedades dos mesmos, através de uso de dois modelos etanol-acetato de etila e celulose-triacetato de celulose. Os dados da mistura líquida mostraram solvatação preferencial; foram tratados com sucesso pelo mesmo modelo aplicado para misturas binárias aquosas. O modelo sólido reproduziu os dados da AC qualitativamente. / This work is aimed at understanding solvation in pure solvents and binary mixtures and, the application of the information obtained in order to analyze the solvents effects on the synthesis of an ionic liquid, and on the dependence of the properties of cellulose acetate films, CA, on the degree of substitution of the ester. To understand salvation, was have used compounds (solvatchromic probes), whose UV-vis spectra are susceptible to the environment properties. In addition to these probes, were used more two tools: (i) Preferential solvation model; it was proposed by our research group and describes the composition of the probe solvation shell, considering the existence of an aggregate between water and organic solvent. (ii) Multi-parameter solvation free energy equations that correlate the solvent dependent properties with solvents properties and their mixtures. At first, we have studied pairs of probes that have similar pKa values and different lipophilicity in protic solvents. We have concluded that solvent acidity and dipolarity/polarizability are the most important properties. These conclusions are supported by theoretical calculations, that have shown the relationship between structural features of the probe and its susceptibility to environment properties. The same set of probes was used in order to study water - protic solvents mixtures. In this, we have applied the above cited solvation model successfully and rationalized the equilibrium constants of the exchange of species present (water, solvent and water -solvent) in the solvation shell with the properties of pure solvents and / or binary mixtures. These results revealed that the composition of solvation shell is controlled by the properties of solvents, in special, lipophilicity and basicity. The probes RB and WB were studied in mixtures of water with alcohols and with aprotic solvents. The intention was to broaden the applicability of the solvation model, for which, we needed to know the molar volume of the aggregate VSolv-W, and the dissociation constant, Kdissoc, of the same. Previously, these two quantities were obtained, simultaneously, by iteration of density data. We have used theoretical calculations in order to obtain VSolv-W and then use it as constant parameter (not adjustable one) in the calculation of Kdissoc. Comparison of the results showed that, in both approaches, the differences between Kdissoc values were minimal. Moreover, the order of Kdissoc has not changed. This observation is due to the fact that the simultaneous calculation of Kdissoc and VSolv-W was always based on a large number of density data (18) so that the interation did not converge to a false minimum; the level of theory used in the theoretic calculations was appropriate. Regarding applications, our results showed the importance of the choice of solvent to the synthesis of an ionic liquid. We have attempted to reproduce the properties of CA by the use of two models, ethanol-ethyl acetate and cellulose triacetate-cellulose. The data of the liquid mixture showed preferential solvation; were successfully treated by the same model applied to aqueous binary mixtures. The solid model reproduces the CA data qualitatively.

Ionic Liquids (ILs) has been attracting attention, both from academia and industry, given the numerous applications of these systems. ILs are salts, usually composed by an organic ion, and a counterion which could be organic or inorganic, and, interestingly they are found at liquid state at room temperature. Our interest in studying ILs comes from its low toxicity. Some recent studies have shown that the toxicity of the ILs ishigher than believed, in particular for biologically relevant systems. The main goal of this research is to study the influence of the ionic liquid 1-tetradecyl-3-methylimidazolium chloride ([C14MIM][Cl]) with membrane systems. To do so, we made use of different lipids: POPC, Sphingomyelin, Cholesterol, POPG, DPPC, DPPG and DMPC. For each of these systems, the influence of ILs concentration were elucidated by means of a systematic study through different experimental techniques: Small Angle X-ray scattering (SAXS), dynamic light scattering (DLS), fluorescence anisotropy, optical microscopy and z-potential. Since [C14MIM][Cl] has a positive charge on the imidazolium group, the superficial charge of all vesicles increased. For zwitterionic vesicles no significant change in size and melting temperature were noticed. The imidazolium-based ionic liquid diminished the gel-fluid transition temperature for negatively charged lipids. For DPPC:DPPG (1:1), for instance, the transition temperature decreased from 42.50±0.13oC to 25.27±0.33oC and for DPPG from 46.12±0.22 oC to 36.6±0.38 oC. For DPPG, the vesicle hydrodynamic diameter increased from 84±0.1nm to 176±0.1nm, whereas for DPPC:DPPG it increased from 95±0.1nm to 196±0.1nm. The electronic density profile, obtained by SAXS, supported the penetration of the [C14MIM][Cl] into the negative bilayer structure. 15 mol% of [C14MIM][Cl] increased the polar head thickness of DPPC vesicles from 11.1±0.6 Å to 18.0±0.7 Å, without alter significantly the inner region of the membrane.Qualitative results obtained with optical microscopy showed that the IL incorporation destabilize the membrane asymmetry (between the leaflets) leading to the formation of pores (evidenced by optical contrast lost) and the presence of buds. We believe that this work could improve the understanding of the effects of ILs in the presence of biological relevant systems / Os líquidos iônicos (LI) tem atraído grande atenção, tanto da academia quanto da indústria, devido às suas numerosas aplicações. LI são sais, normalmente compostos por um íon orgânico, e um contra-íon que pode ser orgânico ou inorgânico, mas que tem como característica ser encontrado no estado líquido à temperaturas próximas a ambiente. Nosso interesse em estudar LIs vem de sua baixa toxicidade, atribuída a sua baixa volatilidade. Entretanto, alguns estudos recentes mostraram que a toxicidade dos LI é maior do que se acreditava, em particular com sistemas de relevância biológica.O objetivo principal desta dissertação é estudar a influência do líquido iônico 1-tetradecil-3-metilimidazólio cloreto ([C14MIM][Cl]) com sistemas de membrana. Para isso, utilizamos diferentes lipídios, como o POPC, esfingomielina, colesterol, POPG, DPPC,DPPG e o DMPC. Para cada um destes sistemas, a influência da concentração de LI foi elucidada por meio de um estudo sistemático através de diferentes técnicas experimentais, tais como: espalhamento de raio-X a baixos ângulos (SAXS), espalhamento dinâmico de luz (DLS), anisotropia de fluorescência, microscopia óptica e potencial-z. Uma vez que o componente iônico de [C14MIM][Cl] tem uma carga positiva no grupo imidazólio, a carga superficial de todas as vesículas estudadas aqui aumentou. Entretanto, para asvesículas compostas pelos lipídeos zwitteriónicos, não tenha sido observada qualquer alteração significativa no tamanho e na temperatura de transição de fase gel-fluido. O [C14MIM][Cl] altera a organização interna entre as moléculas de lipídio com carga negativa. Consequentemente, à medida que a quantidade de LI aumenta, a temperatura de transição de fase diminui e o tamanho médio das vesículas aumenta. Para o sistema DPPC:DPPG (1:1) a temperatura de transição de fase caiu de 42.50 ± 0.13 oC para 25.27 ± 0.33 oC e para as vesículas de DPPG de 46.12±0.22 oC para 36.6±0.38 oC. Quanto ao diâmetro hidrodinâmico médio, no caso do DPPG este valor aumentou de 84±0.1 nm para 176±0.1 nm, enquanto que para a mistura DPPC:DPPG (1:1) ele passou de 95±0.1nm para 196±0.1nm. Indicando assim que o LI incorpora na bicamada lipídica negativamente carregada. O perfil de densidade eletrônica, obtido por SAXS, confirma a penetração do [C14MIM][Cl] na bicamada lipídica. Diferentemente, para a membrana lipídica zwitteriónica o LI tende a se situar perto da região da cabeça polar sem afetar significativamente a região do interior da bicamada lipídica. Por outro lado, a presença de15 mol% de [C14MIM][Cl] aumenta a espessura da região polar das bicamadas das vesículas de DPPC de ~ 11.1±0.6 Å para ~ 18.0±0.7 Å. Os resultados qualitativos da microscopia óptica mostraram que a incorporação da LI desestabiliza a assimetria da membrana entre as camadas interna e externa, além de sugerir o aparecimento de poros (evidenciado pela perda do contraste ótico das vesículas) e estruturas chamadas de buds. Esperamos que este trabalho melhore a compreensão dos efeitos do LI na presença de organismos biológicos.

Apesar de ser utilizado há muito tempo como solvente para espécies orgânicas e inorgânicas, bem como carreador de fármacos, muitos aspectos relativos à auto-associação intermolecular do dimetil sulfóxido (DMSO) e às suas interações com espécies iônicas são ainda motivos de controvérsia na literatura. No presente estudo, a estrutura e ambiente local de dimetil sulfóxido (DMSO) em diferentes meios iônicos foram estudados por meio de três abordagens diferentes. Na primeira abordagem, o efeito de não-coincidência Raman (NCR) observado na banda atribuída ao modo ν(S=O) do DMSO, ca. 1050 cm-1, foi investigado para o líquido puro e em soluções de tetracloreto de carbono (CCl4) e água. Além disso, foi investigado o efeito de espécies iônicas (Kl, KSCN, KBr, TBAN3, TBAOCN, LiClO4, Mg(ClO4)2) na frequência ν(S=O), bem como no NCR das soluções. Os resultados de NCR juntamente com as técnicas de infravermelho, RMN e de medidas de propriedades físico-químicas mostraram que essas espécies iônicas não somente afetam a estrutura de associação do DMSO, como são capazes de interagir fortemente com o solvente. Na segunda abordagem, com a finalidade de modular as propriedades de um líquido iônico, fez-se a análise estrutural das misturas envolvendo DMSO e água como solventes e o líquido iônico EAN como soluto por meio das técnicas de espalhamento de raios-X e de nêutrons. Os resultados mostraram que a estrutura cátion-ânion do EAN é afetada pela presença de DMSO e, que em ambos os solventes são evidentes fortes ligações de hidrogênio entre o cátion EA+ e os oxigênios do solvente e do ânion nitrato. As moléculas de água não afetam drasticamente a estrutura do EAN, pois seu caráter doador/aceptor de LH e seu tamanho permite a formação de pontes entre cátion e o ânion, no entanto, EAN consegue distorcer a rede tridimensional de ligação de hidrogênio da água. Por outro lado, as moléculas de DMSO afastam os ânions da região polar do EA+ na competição pela formação de LH com o cátion e o EAN, por sua vez, provoca a ruptura das estruturas de associação do DMSO. Na terceira abordagem, misturas envolvendo três diferentes SEPs (uma classe de líquidos iônicos); Relina, MUCHCl e DMUCHCl; com DMSO foram investigadas por meio de suas propriedades físico-químicas e por espectroscopia Raman, tendo em vista modular as propriedades dos SEPs. Neste caso, os resultados não apontaram para interações fortes e específicas envolvendo as espécies iônicas e o DMSO, mas a um maior empacotamento do sistema, onde os desvios de suas propriedades físico-químicas com relação à idealidade são negativos e sua mobilidade iônica juntamente com a análise dos espectros vibracionais não evidenciaram interações específicas. No entanto, as viscosidades e densidades diminuíram nas misturas e a mobilidade iônica foi favorecida. / Although it has long been used as a solvent for organic and inorganic species, as well as drug carriers, many aspects concerning the intermolecular self-association of dimethyl sulfoxide (DMSO) and their interactions with ionic species are still controversial in the literature. In the present study, the structure and local environment of dimethyl sulfoxide (DMSO) in different ionic media were studied using three different approaches. In the first approach, the Raman non-coincidence effect (NCE) observed in the band assigned to the DMSO ν(S = O) mode, ca. 1050 cm-1, was investigated for the pure liquid and in its solutions of carbon tetrachloride (CCl4) and water. In addition, the effect of ionic species (K1, KSCN, KBr, TBAN3, TBAOCN, LiClO4, Mg (ClO4)2) on the frequency ν(S = O) as well as the NCE of the solutions were investigated. The results of NCR together with the infrared, NMR and physico-chemical properties measurements showed that these ionic species not only affect the association structure of DMSO, but are also capable of interacting strongly with the solvent. In the second approach, with the purpose of modulating the properties of an ionic liquid, the structural analysis of the mixtures involving DMSO and water as solvents and the ionic liquid EAN as a solute were carried out by X-ray and neutron scattering techniques. The results showed that the cation-anion structure of the EAN is affected by the presence of DMSO and that in both solvents strong hydrogen bonds between the EA+ cation and the oxygen from solvent and from nitrate anion are evident. The water molecules do not affect the structure of the EAN drastically, because its LH donor/acceptor character and its size allows the formation of bridges between cation and anion, however, EAN can distort the hydrogen bonding three-dimensional network in water. On the other hand, the DMSO molecules repels the anions from the polar head of EA+ in the competition in forming LH with the cation, however EAN break down DMSO association structures. In the third approach, mixtures involving three different SEPs (a class of ionic liquids); Relina, MUCHCl and DMUCHCl; with DMSO were investigated by means of their physicochemical properties and by Raman spectroscopy, in order to modulate the properties of SEPs. In this case, the results did not point to strong and specific interactions involving the ionic species and DMSO, but to a greater packaging of the system, where the deviations of its physicochemical properties with respect to the ideality are negative and its ionic mobility together with the analysis of the vibrational spectra showed no specific interactions. However, the viscosities and densities decreased in the mixtures and the ionic mobility was favored.

Ce projet de thèse porte sur la recherche de nouveaux électrolytes et additifs dans le but d’améliorer la cyclabilité d’une électrode négative composite de formule Si0.32Ni0.14Sn0.17Al0.04C0.35 et d’obtenir une interface électrode|électrolyte stable. En effet, comme la plupart des matériaux à base de silicium, ce composite de grande capacité (plus de 600 mA.h.g-1) souffre actuellement d’une faible durée de vie provenant essentiellement des expansions volumiques qu’il subit lors de sa lithiation et de sa SEI défaillante. Deux types d'électrolytes ont été évalués : (i) un mélange de carbonates d’alkyles EC/PC/3DMC auquel a été ajouté un sel de lithium (LiPF6, LiTFSI, LiFSI ou LiDFOB) ainsi que des additifs aidant à la formation de la SEI tels que le carbonate de vinylène (VC) ou le carbonate de fluoroéthylène (FEC), (ii) des liquides ioniques (LI) contenant un cation ammonium quaternaire (N1114+), imidazolium (EMI+) ou pyrrolidinium (PYR+), associé à un anion à charge délocalisée comme le bis(trifluorométhanesulfonyl)amidure (TFSI-) ou le bis(fluorosulfonyl)amidure (FSI-). L’analyse du diagramme d’ionicité de Walden a permis de mettre en évidence la bonne dissociation de LiFSI et LiPF6 dans EC/PC/3DMC assurant ainsi des conductivités ioniques supérieures à 12 mS.cm-1. Bien que possédant des propriétés de transport a priori moins intéressantes dans ce mélange ternaire que les autres sels, LiDFOB forme en réduction une SEI permettant au composite de fournir les meilleures performances en cyclage sans additif avec 560 mA.h.g-1 pour un rendement coulombique de 98,4%. L’ajout d’additif est cependant nécessaire pour atteindre les objectifs fixés par le projet en termes de rendement coulombique (>99,5%). Dans ce cas, l’ajout de 2%VC+10%FEC au mélange ternaire est le plus intéressant avec LiPF6. Le matériau fourni ainsi des capacités de 550 mA.h.g-1 durant une centaine de cycles à un régime de C/5 avec un rendement coulombique de 99,8%. En milieu LI, les performances optimales sont atteintes avec le [EMI][FSI] et 1 mol.L-1 de LiFSI. Le composite atteint alors une capacité de 635 mA.h.g-1 durant 100 cycles à un régime de C/5 avec un rendement coulombique très proche de 100%, tout en s’affranchissant de l’ajout d’additifs. Malgré une viscosité bien plus élevée que celles des mélanges de carbonates d’alkyles, cette formulation permet de générer une SEI plus stable dont la nature, principalement minérale, est issue majoritairement des produits de réduction de FSI-. / This study focuses on new electrolytes and additives in order to improve the cyclability of a Si0.32Ni0.14Sn0.17Al0.04C0.35 negative composite electrode (Si-Sn) and to obtain a stable electrolyte|electrolyte interface. Indeed, like most silicon-based materials, this high-capacity Si-Sn composite (over 600 mA.hg-1) currently suffers from a short cycle life due to volume expansion during charge-discharge processes leading to the degradation of the SEI. To improve the quality of the interface, two kinds of electrolytes were evaluated: (i) mixtures of alkyl carbonates EC/PC/3DMC in which a lithium salt (LiPF6, LiTFSI, LiFSI or LiDFOB) and additives like SEI builder (vinylene carbonate (VC) or fluoroethylene carbonate (FEC)) were added, (ii) ionic liquids (IL) based on quaternary ammonium (N1114+), imidazolium (EMI+) or pyrrolidinium (PYR+) cation, associated with delocalized charge anions such as bis(trifluoromethanesulfonyl)imide (TFSI-) or bis(fluorosulfonyl)imide (FSI-). The Walden diagram confirms the efficient dissociation of LiFSI and LiPF6 in EC/PC/3DM ensuring ionic conductivities as high as 12 mS.cm-1. Although possessing limited transport properties in such a ternary mixture compared to other salts, LiDFOB forms, without additional additives, an high quality SEI allowing the composite to provide the best performances in half cells (560 mA.hg-1 and 98.4% coulombic efficiency). The use of additive is however necessary to reach the objectives fixed by the ANR research project in terms of coulombic efficiency (>99.5%). In this case, the addition of 2%VC+10%FEC to the ternary mixture is the most interesting composition with LiPF6 as lithium salt. So, the Si-Sn nanocomposite material reaches 550 mA.h.g-1 during 100 cycles at C/5 with 99.8% efficiency. In IL, the best performances are achieved in [EMI][FSI]/LiFSI (1 mol.L-1). The performances of the Si-Sn composite reaches 635 mA.h.g-1 for 100 cycles at C/5 with coulombic efficiency close to 100%, without additives. This electrolyte formulation generates a stable SEI which the mainly mineral composition, is predominantly derived from the reduction products of FSI-.

L'un des principaux domaines de recherche en chimie et en ingénierie chimique implique l'utilisation de liquides ioniques et de nanomatériaux comme alternatives à de nombreux produits chimiques et processus chimiques, comme ce dernier étant actuellement considérés comme non respectueux de l'environnement. Leur utilisation potentiel comme nouveaux fluides de transfert de chaleur et matériaux de stockage de chaleur, qui peuvent obéir à la plupart des principes de la chimie verte, nécessite l'étude expérimentale et théorique des mécanismes de transfert de chaleur dans les fluides complexes comme les ionanofluides. Le but de cette thèse était d'étudier les ionanofluides, qui consistent en la dispersion de nanomatériaux dans un liquide ionique.Le premier objectif de ce travail était de mesurer les propriétés thermophysiques des liquides ioniques et ionanofluides, à savoir la conductivité thermique, la viscosité, la densité et la capacité thermique dans une gamme de température comprise entre -10 et 150 ºC et à pression atmosphérique. Dans ce sens, les propriétés thermophysiques d'un ensemble considérable de liquides ioniques et d'ionanofluides ont été mesurées, avec un accent particulier sur la conductivité thermique des fluides. Les liquides ioniques étudiés étaient [C2mim][EtSO4], [C4mim][(CF3SO2)2N], [C2mim][N(CN)2], [C4mim][N(CN)2], [C4mpyr][N(CN)2], [C2mim][SCN], [C4mim][SCN], [C2mim][C(CN)3], [C4mim][C(CN)3], [P66614][N(CN)2], [P66614][Br] et leurs suspensions avec 0.5% et 1% w/w de nanotubes de carbone multi-parois (MWCNTs - de l'anglais multi-walled carbon nanotubes). Les résultats obtenus montrent qu'il y a une augmentation substantielle de la conductivité thermique du fluide de base due à la suspension du nanomatériau, en considérant les deux fractions massiques. Cependant, l'amélioration varie de manière significative lorsqu'on considère différents liquides ioniques de base, avec une gamme comprise entre 2 et 30%, avec une température croissante. Ce fait rend plus difficile l'unification des informations obtenues afin d'obtenir un modèle permettant de prédire l'amélioration de la conductivité thermique. Les modèles actuellement utilisé pour calculer la conductivité thermique des nanofluides présentent des valeurs considérablement sous-estimées par rapport aux valeurs expérimentales, en partie à cause des considérations sur le rôle de l'interface solide-liquide sur le transport de la chaleur.En ce qui concerne la densité, l'impact de l'ajout de MWCNTs sur la densité du fluide de base est très faible, variant entre 0.25% et 0.5% pour 0.5% w/w et 1% w/w MWCNTs, respectivement. Cela était assez attendu et est dû à la différence considérable de densité entre les deux types de matériaux. Cependant, la viscosité était la propriété pour laquelle les valeurs les plus élevées d' augmentation ont été vérifiées, allant de 28 à 245% pour les deux fractions massiques de MWCNT. La capacité calorifique était la seule des quatre propriétés mentionnées ci-dessus à ne pas être étudiée dans ce travail en raison de problèmes techniques avec le calorimètre à utiliser. Néanmoins, la quantité de données recueillies sur les propriétés thermophysiques restantes était extensif. On pense que ce dernier contribue de manière significative à une base de données croissante des propriétés des liquides ioniques et des ionanofluides, tandis que en fournissant un aperçu de la variation des propriétés obtenues à partir de la suspension de MWCNTs dans des liquides ioniques.(...) / One of the main areas of research in chemistry and chemical engineering involves the use of ionic liquids and nanomaterials as alternatives to many chemical products and chemical processes, as the latter are currently considered to be environmentally non-friendly. Their possible use as new heat transfer fluids and heat storage materials, which can obey to most principles of green chemistry or green processing, requires the experimental and theoretical study of the heat transfer mechanisms in complex fluids, like the ionanofluids.
It was the purpose of this dissertation to study ionanofluids, which consist on the dispersion of nanomaterials in an ionic liquid.The first objective of this work was to measure thermophysical properties of ionic liquids and ionanofluids, namely thermal conductivity, viscosity, density and heat capacity in a temperature range between -10 e 150 ºC 
and at atmospherical pressure. In this sense, the thermophysical properties of a considerable set of ionic liquids and ionanofluids were measured, with particular emphasis on the thermal conductivity of the fluids. The ionic liquids studied were [C2mim][EtSO4], [C4mim][(CF3SO2)2N], [C2mim][N(CN)2], [C4mim][N(CN)2], [C4mpyr][N(CN)2], [C2mim][SCN], [C4mim][SCN], [C2mim][C(CN)3], [C4mim][C(CN)3], [P66614][N(CN)2], [P66614][Br] and their suspensions with 0.5% and 1% w/w of multi-walled carbon nanotubes (MWCNTs). The results obtained show that there is a substantial enhancement of the thermal conductivity of the base fluid due to the suspension of the nanomaterial, considering both mass fractions. However, the enhancement varies significantly when considering different base ionic liquids, with a range between 2 to 30%, with increasing temperature. This fact makes it more difficult to unify the obtained information in order to obtain a model that allows predicting the enhancement of the thermal conductivity. Current models used to calculate the thermal conductivity of nanofluids present values that are considerably underestimated when compared to the experimental ones, somewhat due to the considerations on the role of the solid-liquid interface on heat transport.Considering density, the impact from the addition of MWCNTs on the base fluid’s density is very low, ranging between 0.25% and 0.5% for 0.5% w/w and 1% w/w MWCNTs, respectively. This was fairly expected and is due to the considerable difference in density between both types of materials. However, viscosity was the property for which the highest values of enhancement were verified, ranging between 28 and 245% in both mass fractions of MWCNTs. The heat capacity was the only of the four properties mentioned above not to be studied in this work due to technical issues with the calorimeter to be used. Nevertheless, the amount of data collected on the remainder thermophysical properties was extensive. It is believed that the latter contributes meaningfully to a growing database of ionic liquids and ionanofluids’ properties, while providing insight on the variation of said properties obtained from the suspension of MWCNTs in ionic liquids.The second objective of this work consisted on the development of molecular interaction models between ionic liquids and highly conductive nanomaterials, such as carbon nanotubes and graphene sheets. These models were constructed based on quantum calculations of the interaction energy between the ions and a cluster, providing interaction potentials. Once these models were obtained, a second stage on this computational approach entailed to simulate, by Molecular Dynamics methods, the interface nanomaterial/ionic liquid, in order to understand the specific interparticle/molecular interactions and their contribution to the heat transfer. This would allow to study both structural properties, such as the ordering of the ionic fluid at the interface, and dynamic ones, such as residence times and diffusion. (...)

Les mécanismes d’électrodéposition réalisés à partir d'électrolytes à base de liquides ioniques ne sont pas très bien compris en raison de l’organisation structurale complexe de ces électrolytes. Dans cette thèse, nous étudions les relations qui existent entre la morphologie des films, les propriétés électrochimiques ainsi que la structure de l'électrolyte liquide ionique. Plusieurs solutions ont été étudiées: CuCl, CuCl2 et CuSO4 dans 1-éthyl-3-méthylimidazolium éthyl-sulfate [EMIM] [EtSO4]; AgTFSI, CuTFSI2 et AlTFSI3 en 1-éthyl-3-méthylimidazolium bis(trifluorométhylsulfonyl)imide [EMIM] [TFSI]. Des mesures de cyclovoltammétrie montrent que les réductions de l’argent et du cuivre sont quasi-réversibles et se produisent par une réaction de transfert mono-électronique {(Ag (I) → Ag (0), (Cu (II) → Cu (I)) et (Cu (I) → Cu (0)}. La réduction de l'aluminium est irréversible. Les coefficients de diffusion augmentent avec la température de l'électrolyte et sont également influencés par l'état d'oxydation du métal et des anions en solution. Des films minces métalliques ont été obtenus pour toutes les solutions, sauf pour AlTFSI3. L'analyse par XRD et EDX montrent que les films sont cristallins et sont principalement constitués de cuivre ou d'argent pur. Leur morphologie est contrôlée par la température, du temps et du potentiel d’électrodéposition. D'une manière générale, l'élévation du temps de dépôt et de la température augmente la couverture du film et de la taille des particules, tandis que l'augmentation du potentiel de dépôt diminue la taille des particules. La structure des électrolytes a été étudiée par Raman et IR spectroscopies et interprétée à l’aide de méthodes théoriques de chimie quantique. Pour AgTFSI-[EMIM][TFSI], le cation d’argent est solvaté par trois anions TFSI-. Pour CuCl2-[EMIM][EtSO4], le cation de cuivre est solvaté par deux anions de chlore et deux anions EtSO4. / Deposition mechanisms from ionic liquid-based electrolytes are not fully understood due to difficulties in probing the electrolyte structure. In this study, we investigate the links between films morphology, electrochemical properties of the electrolyte and electrolyte structure. Several solutions were investigated: CuCl, CuCl2 and CuSO4 in 1-ethyl-3-methylimidazolium ethylsulphate [EMIM][EtSO4]; AgTFSI, CuTFSI2 and AlTFSI3 in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [EMIM][TFSI]. Cyclic-voltammetry shows that silver and copper reductions are quasi-reversible and occur by one-electron transfer reaction {(Ag(I)→Ag(0), (Cu(II)→Cu(I)) and (Cu(I)→Cu(0)}. Aluminium reduction is irreversible. The diffusion coefficients increase with electrolyte temperature, and are also influenced by the metal oxidation state and anions in solution. Metallic thin films were obtained for all the solutions except AlTFSI3. XRD and EDX analysis show that the films are crystalline and consist mainly of pure copper or silver. Their morphology is controlled by the deposition temperature, time and potential. In general, increasing the deposition time and temperature increases the film coverage and particle size, whereas increasing the deposition potential decreases the particle size. The electrolytes structure was investigated by Raman and IR spectroscopies, supported by theoretical calculations. For the AgTFSI-[EMIM][TFSI], silver cation is solvated by three TFSI-. For the CuCl2-[EMIM][EtSO4], copper cation is solvated by two chlorines and two EtSO4-.

The concept of a self-incompatible solvent is introduced as a molecule composed of two parts (compound 1 and 2) with unfavourable interactions. A third compound will be readily dissolved in this solvent to diminish this unfavourable interaction by dilution. The more incompatible compounds 1 and 2 are, the stronger this behaviour is expected to be. In this work, ionic liquids comprising non-polar carbon chain and polar ionic group are chosen to serve as a model of self-incompatible solvent. The interactions parameters k of the ionic liquids with active ingredients are investigated to examine the effect of self-incompatibility of the ionic liquid molecule. On the other hand, phase separation between compounds 1 and 2 will reduce the positive effect of self-incompatibility. The tendency of phase separation is increasing with increasing size of the two compounds. Thus, if compounds 1 and 2 are blocks tied together into a block copolymer, one expects a decreasing ability of the block copolymer to dissolve an active ingredient with increasing block length. In this work the ability of polybutadiene-block-poly(2-vinylpyridine) (PB-b-P2VP) block copolymers to dissolve the model compound anthracene is investigated. As expected, the solubility indeed decreases with increasing block length.

La Captura y Almacenamiento de dióxido de Carbono (CAC), es una tecnología orientada a mitigar el impacto de los gases de efecto invernadero producidos en la quema de combustibles fósiles en procesos industriales y de generación de energía, donde la captura de dióxido de carbono (CO2) supone el cuello de botella del proceso, y por tanto donde deben centrarse los esfuerzos. En este contexto, el objetivo de este trabajo es la intensificación del proceso de absorción de CO2 convencional en dos etapas: i) Sustitución del equipamiento convencional (e.g. torres de absorción) por sistemas de membranas para una absorción no dispersiva que elimine el arrastre de gotas y, ii) Sustitución del absorbente de referencia (monoetanolamina, MEA) por líquidos iónicos, con presión de vapor despreciable, que permite eliminar las pérdidas de disolvente por volatilización. En la presente Tesis Doctoral se desarrolla un proceso con cero emisiones de disolvente mediante la integración de equipos de membranas y líquidos iónicos, como estrategia para la intensificación del proceso de captura de CO2 de post-combustión. / Carbon dioxide Capture and Storage (CCS), is a technology aimed at mitigating greenhouse gas impacts from fossil fuels combustion in industrial and energy-related processes where, carbon dioxide (CO2) capture is the bottleneck step where the efforts have to be applied. In this context, the aim of this work is to intensify the absorption process by two steps: i) Substitution of conventional equipment (e.g. scrubbers) for non-dispersive absoprtion membrane systems to avoid drops dragging and, ii) Substitution of the reference absorption solvent (monoethanolamine, MEA) for ionic liquids, with negligible vapour pressure, to avoid solvent losses due to volatilization of the solvent into gas stream. Thereby, in this PhD Thesis a zero solvent emission process trough the integration of membrane systems and ionic liquids is developed as a process intensification strategy for the recovery of CO2 from post-combustion streams.