O objetivo deste trabalho é estudar a reatividade de acilação de celulose por anidridos de ácidos carboxílicos sob condições homogêneas em solventes apróticos dipolares (SAD), incluindo LiCl/N,N-dimetilacetamida (DMAC) e líquidos iônicos (LIs)/SAD. Os factores que contribuem para a reatividade foram quantificados através do estudo da dependência das constantes de velocidade e parâmetros de ativação sobre a composição do solvente. Após estabelecer que a condutividade é uma técnica experimental adequada para calcular as constantes de velocidade, foi estudada a acilação não catalisada e catalisada de celulose microcristalina, MCC. Foram empregados anidridos de ácidos carboxílicos com diferentes grupos acila (acetil a hexanoil; Nc = 2 a 6) nos seguintes sistemas de solventes: LiCl/DMAC, misturas de LI cloreto de 1-alil-3-metilimidazólio ( AlMeImCl ) e acetonitrila (MeCN), DMAC , dimetilsulfóxido (DMSO ) e sulfolano. Na celulose, a unidade anidra de glucose possui um grupo hidroxila primário e dois hidroxilas secundários. Usamos ciclohexilmetanol, CHM, e trans-1 ,2- ciclo-hexanodiol, CHD , como compostos modelo para os grupos (OH) primário e secundários, respectivamente. As razões das constantes de velocidade de acilação dos compostos modelo (CHM; Prim-OH) e (CHD; SEC-OH) foram empregados, após correção, a fim de dividir as constantes de velocidade global da reação de MCC em contribuições dos grupos (OH) presentes. Para os compostos modelo, verificou-se que k3 (Prim-OH) /k3 (Sec-OH) > 1, semelhante as reações de celulose sob condições heterogéneas; esta relação aumenta como uma função do aumento da Nc. As constantes de velocidade globais e parciais de acilação de MCC diminuim de anidrido etanóico a butanóico e, em seguida, aumentam para anidrido pentanóico e hexanóico, devido a mudanças sutis em - e compensações da entalpia e entropia de ativação. As constantes de velocidade para a acetilação de MCC, por anidrido etanóico na presença de concentrações crescentes do LI em DMAC, MeCN, DMSO e sulfolano foram calculados a partir de dados de condutividade. As constantes de velocidade de terceira ordem mostraram dependência linear sobre [LI]. Estes resultados foram explicados assumindo que o reagente é celulose ligado ao LI por ligação de hidrogénio. Isto foi confirmado pelos dados cinéticos da acetilação de CHM, espectroscopia de IV do último composto, e de celobiose nas misturas de LI/SAD e condutividade das misturas de solventes binários, na ausência e presença de MCC. A acetilação de celulose é mais rápida nas misturas de em LI com DMAC e DMSO do que com MeCN e sulfolano. Esta diferença é explicada, em parte, com base na alta viscosidade das soluções de biopolímeros em LI/sulfolano. Obteve-se mais informações sobre os efeitos do solvente molecular a prtir das propriedades microscópicas dos solventes e simulações por dinâmica molecular, DM. Os dados solvatocrômicos (polaridade empírica e basicidade) têm mostrado a importância da basicidade do solvente; solventes mais básicos formam ligações de hidrogênio mais fortes com os grupos (OH) da celulose, aumentando sua acessibilidade e, consequentemente sua reatividade. Este é o caso de DMAC e DMSO. Os resultados das simulações por DM indicaram a formação de ligações de hidrogénio, entre os grupos (OH) da unidade de glucose anidra do MCC, (Cl-) de LI, e o dipolo do DMAC e DMSO . Observamos que a acilação de celulose em LiCl/DMAC é eficientemente catalisada por imidazol, mas não pelo cloreto de tosila. Resultados de IV de FT e RMN de 1H indicaram a formação de N-acilimidazol que é o agente de acilação. As constantes globais e parciais de velocidade de acilação do MCC diminuiram de anidirido etanóico a butanóico e depois aumentou para anidrido pentanóico e hexanóico, devido a mudanças sutis em- e compensações da entalpia e entropia de ativação. / The objective of this work is to study the reactivity in cellulose acylation by carboxylic acid anhydrides under homogeneous conditions in dipolar aprotic solvents (DAS), including LiCl/ N,N-dimethylacetamide (DMAC) and ionic liquids (ILs)/DAS. Factors that contribute to reactivity were quantified by studying the dependence of reaction rates on temperature and solvent composition. After establishing that conductivity is an appropriate experimental technique to calculate the rate constants, we studied the kinetics of the homogeneous uncatalyzed and catalyzed acylation of microcrystalline cellulose, MCC, with carboxylic acid anhydrides with different acyl chain-length (Nc; ethanoic to hexanoic) in the following solvent systems: LiCl/DMAC; mixtures of the IL, 1-allyl-3-methylimidazolium chloride, (AlMeImCl) and acetonitrile (MeCN), DMAC, dimethyl sulfoxide (DMSO) and sulfolane. The anhydroglucose unit of cellulose carries one primary- and two secondary hydroxyl groups. We used cyclohexylmethanol, CHM, and trans-1,2-cyclohexanediol, CHD, as model compounds for the hydroxyl groups of the anhydroglucose unit of cellulose. The ratios of rate constants of acylation of primary (CHM; Prim-OH) and secondary (CHD; Sec-OH) groups were employed, after correction, in order to split the overall rate constants of the reaction of MCC into contributions from the discrete OH groups. For the model compounds, we have found that k3 (Prim-OH)/k3 (Sec-OH) > 1, akin to reactions of cellulose under heterogeneous conditions; this ratio increases as a function of increasing Nc. The overall and partial rate constants of the acylation of MCC decrease from ethanoic- to butanoic anhydride and then increase for pentanoic- and hexanoic anhydride, due to subtle changes in- and compensations of the enthalpy and entropy of activation. Rate constants for the acetylation of MCC, by ethanoic anhydride in the presence of increasing concentrations of the ionic liquid, IL, 1-allyl-3-methylimidazolium chloride in dipolar aprotic solvents, DAS, N,N-dimethylacetamide, DMAC, acetonitrile, MeCN, dimethylsulfoxide, DMSO and sulfolane, have been calculated from conductivity data. The third order rate constants showed a linear dependence on [IL]. These results have been explained by assuming that the reactant is cellulose hydrogen-bonded to the IL. This is corroborated by kinetic data of the acetylation of cyclohexyl methanol, FTIR spectroscopy of the latter compound, and cellobiose in mixtures of IL/DAS, and conductivity of the binary solvent mixtures in absence, and presence of MCC. Cellulose acetylation is faster in IL/DMAC and IL/DMSO than in IL/MeCN and IL/Sulfolane. This difference is explained, in part, based the high viscosity of the biopolymer solutions in IL-Sulfolane. Additional explanation came from microscopic solvents properties and molecular dynamics, MD simulations. The solvatochromic data (empirical polarity and basicity) have shown the importance of solvent basicity; basic solvents hydrogen-bond to the hydroxyl groups of cellulose increasing its accessibility, hence its reactivity. This is the case of DMAC and DMSO. Results of MD simulations indicated hydrogen-bond formation between the hydroxyl groups of the anhydroglucose unit of MCC, (Cl-) of the IL, and the dipole of the DMAC and DMSO. It has been observed that cellulose acylation in LiCl/DMAC is efficiently catalyzed by imidazole, but not by p-tosyl chloride. FTIR and 1H NMR have indicated the formation of N-acylimidazole which is the acylating agent. The overall and partial rate constants of the acylation of MCC decreased from ethanoic- to butanoic-anhydride and then increased for pentanoic- and hexanoic anhydride, due to subtle changes in- and compensations of the enthalpy and entropy of activation.

O objetivo deste trabalho é estudar a reatividade de acilação de celulose por anidridos de ácidos carboxílicos sob condições homogêneas em solventes apróticos dipolares (SAD), incluindo LiCl/N,N-dimetilacetamida (DMAC) e líquidos iônicos (LIs)/SAD. Os factores que contribuem para a reatividade foram quantificados através do estudo da dependência das constantes de velocidade e parâmetros de ativação sobre a composição do solvente. Após estabelecer que a condutividade é uma técnica experimental adequada para calcular as constantes de velocidade, foi estudada a acilação não catalisada e catalisada de celulose microcristalina, MCC. Foram empregados anidridos de ácidos carboxílicos com diferentes grupos acila (acetil a hexanoil; Nc = 2 a 6) nos seguintes sistemas de solventes: LiCl/DMAC, misturas de LI cloreto de 1-alil-3-metilimidazólio ( AlMeImCl ) e acetonitrila (MeCN), DMAC , dimetilsulfóxido (DMSO ) e sulfolano. Na celulose, a unidade anidra de glucose possui um grupo hidroxila primário e dois hidroxilas secundários. Usamos ciclohexilmetanol, CHM, e trans-1 ,2- ciclo-hexanodiol, CHD , como compostos modelo para os grupos (OH) primário e secundários, respectivamente. As razões das constantes de velocidade de acilação dos compostos modelo (CHM; Prim-OH) e (CHD; SEC-OH) foram empregados, após correção, a fim de dividir as constantes de velocidade global da reação de MCC em contribuições dos grupos (OH) presentes. Para os compostos modelo, verificou-se que k3 (Prim-OH) /k3 (Sec-OH) > 1, semelhante as reações de celulose sob condições heterogéneas; esta relação aumenta como uma função do aumento da Nc. As constantes de velocidade globais e parciais de acilação de MCC diminuim de anidrido etanóico a butanóico e, em seguida, aumentam para anidrido pentanóico e hexanóico, devido a mudanças sutis em - e compensações da entalpia e entropia de ativação. As constantes de velocidade para a acetilação de MCC, por anidrido etanóico na presença de concentrações crescentes do LI em DMAC, MeCN, DMSO e sulfolano foram calculados a partir de dados de condutividade. As constantes de velocidade de terceira ordem mostraram dependência linear sobre [LI]. Estes resultados foram explicados assumindo que o reagente é celulose ligado ao LI por ligação de hidrogénio. Isto foi confirmado pelos dados cinéticos da acetilação de CHM, espectroscopia de IV do último composto, e de celobiose nas misturas de LI/SAD e condutividade das misturas de solventes binários, na ausência e presença de MCC. A acetilação de celulose é mais rápida nas misturas de em LI com DMAC e DMSO do que com MeCN e sulfolano. Esta diferença é explicada, em parte, com base na alta viscosidade das soluções de biopolímeros em LI/sulfolano. Obteve-se mais informações sobre os efeitos do solvente molecular a prtir das propriedades microscópicas dos solventes e simulações por dinâmica molecular, DM. Os dados solvatocrômicos (polaridade empírica e basicidade) têm mostrado a importância da basicidade do solvente; solventes mais básicos formam ligações de hidrogênio mais fortes com os grupos (OH) da celulose, aumentando sua acessibilidade e, consequentemente sua reatividade. Este é o caso de DMAC e DMSO. Os resultados das simulações por DM indicaram a formação de ligações de hidrogénio, entre os grupos (OH) da unidade de glucose anidra do MCC, (Cl-) de LI, e o dipolo do DMAC e DMSO . Observamos que a acilação de celulose em LiCl/DMAC é eficientemente catalisada por imidazol, mas não pelo cloreto de tosila. Resultados de IV de FT e RMN de 1H indicaram a formação de N-acilimidazol que é o agente de acilação. As constantes globais e parciais de velocidade de acilação do MCC diminuiram de anidirido etanóico a butanóico e depois aumentou para anidrido pentanóico e hexanóico, devido a mudanças sutis em- e compensações da entalpia e entropia de ativação. / The objective of this work is to study the reactivity in cellulose acylation by carboxylic acid anhydrides under homogeneous conditions in dipolar aprotic solvents (DAS), including LiCl/ N,N-dimethylacetamide (DMAC) and ionic liquids (ILs)/DAS. Factors that contribute to reactivity were quantified by studying the dependence of reaction rates on temperature and solvent composition. After establishing that conductivity is an appropriate experimental technique to calculate the rate constants, we studied the kinetics of the homogeneous uncatalyzed and catalyzed acylation of microcrystalline cellulose, MCC, with carboxylic acid anhydrides with different acyl chain-length (Nc; ethanoic to hexanoic) in the following solvent systems: LiCl/DMAC; mixtures of the IL, 1-allyl-3-methylimidazolium chloride, (AlMeImCl) and acetonitrile (MeCN), DMAC, dimethyl sulfoxide (DMSO) and sulfolane. The anhydroglucose unit of cellulose carries one primary- and two secondary hydroxyl groups. We used cyclohexylmethanol, CHM, and trans-1,2-cyclohexanediol, CHD, as model compounds for the hydroxyl groups of the anhydroglucose unit of cellulose. The ratios of rate constants of acylation of primary (CHM; Prim-OH) and secondary (CHD; Sec-OH) groups were employed, after correction, in order to split the overall rate constants of the reaction of MCC into contributions from the discrete OH groups. For the model compounds, we have found that k3 (Prim-OH)/k3 (Sec-OH) > 1, akin to reactions of cellulose under heterogeneous conditions; this ratio increases as a function of increasing Nc. The overall and partial rate constants of the acylation of MCC decrease from ethanoic- to butanoic anhydride and then increase for pentanoic- and hexanoic anhydride, due to subtle changes in- and compensations of the enthalpy and entropy of activation. Rate constants for the acetylation of MCC, by ethanoic anhydride in the presence of increasing concentrations of the ionic liquid, IL, 1-allyl-3-methylimidazolium chloride in dipolar aprotic solvents, DAS, N,N-dimethylacetamide, DMAC, acetonitrile, MeCN, dimethylsulfoxide, DMSO and sulfolane, have been calculated from conductivity data. The third order rate constants showed a linear dependence on [IL]. These results have been explained by assuming that the reactant is cellulose hydrogen-bonded to the IL. This is corroborated by kinetic data of the acetylation of cyclohexyl methanol, FTIR spectroscopy of the latter compound, and cellobiose in mixtures of IL/DAS, and conductivity of the binary solvent mixtures in absence, and presence of MCC. Cellulose acetylation is faster in IL/DMAC and IL/DMSO than in IL/MeCN and IL/Sulfolane. This difference is explained, in part, based the high viscosity of the biopolymer solutions in IL-Sulfolane. Additional explanation came from microscopic solvents properties and molecular dynamics, MD simulations. The solvatochromic data (empirical polarity and basicity) have shown the importance of solvent basicity; basic solvents hydrogen-bond to the hydroxyl groups of cellulose increasing its accessibility, hence its reactivity. This is the case of DMAC and DMSO. Results of MD simulations indicated hydrogen-bond formation between the hydroxyl groups of the anhydroglucose unit of MCC, (Cl-) of the IL, and the dipole of the DMAC and DMSO. It has been observed that cellulose acylation in LiCl/DMAC is efficiently catalyzed by imidazole, but not by p-tosyl chloride. FTIR and 1H NMR have indicated the formation of N-acylimidazole which is the acylating agent. The overall and partial rate constants of the acylation of MCC decreased from ethanoic- to butanoic-anhydride and then increased for pentanoic- and hexanoic anhydride, due to subtle changes in- and compensations of the enthalpy and entropy of activation.

Afin de mieux comprendre et de dépasser les limites actuelles des systèmes métal-air non-aqueux, le mécanisme de réduction de l’oxygène (ORR) a été étudié en présence de cation alcalins dans divers solvants aprotiques. Sur la base de caractérisations électrochimiques sur électrode statique et d’électrodes tournantes disque-anneau, un mécanisme unique a été proposé afin de rendre compte de l’ORR en présence de cations alcalins. De plus, les différences observées d’un solvant à l’autre ont été expliquées en termes de capacité du solvant à solvater à la fois le cation alcalin en présence et l’anion superoxyde, mais aussi à sa capacité à séparer les paires d’ions. Un modèle cinétique basé sur ce mécanisme a montré un excellent accord avec les résultats expérimentaux. / In order to better understand and overcome the current limitations of non-aqueous metal-air batteries, the oxygen reduction reaction (ORR) mechanism has been studied in presence of different alkali metal cations in several aprotic solvents. Based on electrochemical characterizations on static electrode and rotating ring-disk electrode, a unique mechanism has been proposed to account for ORR in presence of alkali metal cations. It has been further showed that the differences observed from one solvent to another could be linked to the solvent’s ability to solvate both the alkali metal cation and the superoxide anion, as well as its capability to separate ion-pairs. A kinetic model based on this mechanism has shown very good agreement with experimental results.

The doctoral theses deal with electrochemical deposition of lead, tin, silicon and germanium from aprotic electrolytes in anhydrous inert atmosphere. Deposited layers are studied from the perspective of their surface and of electrochemical characteristics.

The doctoral theses deal with electrochemical deposition of lead, tin, silicon and germanium from aprotic electrolytes in anhydrous inert atmosphere. Deposited layers are studied from the perspective of their surface and of electrochemical characteristics.

This master´s thesis deals different types of the aprotic electrolytes for supercapacitors and investigates by impedance spectroscopy to conductivity and method cyclic voltametry to measure dimension potential windows. Used aprotic solvents: propylencarbonate, dimethylsulfoxide, N, N dimethylformamide, ethylencarbonate, dimethylcarbonate, diethylcarbonate and acetonitrile. In the aprotic solvents were appended salts: LiClO4, NaClO4, KClO4, LiBF4, LiPF6, TEABF4 and TMABF4. From these compounds were prepared solutions with the different molar concentrations.

Aprotic solvents are organic solvents which do not easily react with a substance dissolved in it and they do not exchange protons despite of their high ion and polar group dissolving power. Therefore, this characteristic property makes aprotic solvents very suitable intermediates in many industries producing pharmaceuticals, textile auxiliaries, plasticizers, stabilizers, adhesives and ink. Dehydration of these mixtures and recirculation of valuable materials are substantial issues in industrial applications. The conventional method for recovery of aprotic solvents has been distillation, which requires excessive amount of energy to achieve desired recovery. Hydrophilic pervaporation, which is a membrane based dehydration method with low energy consumption, may become an alternative. Because of high dissolving power of aprotic solvents only inorganic membranes can be employed for this application. In this study three types of inorganic membranes (NaA zeolite, optimized silica and HybSi) were employed. Main objective of this studys to investigate effect of membrane type and various operationg parameters (feed composition at a range of 50-5% and temperature at a range of 50-100oC) on pervaporative dehydration of aprotic solvents / dimethylacetamide, dimethylformamide and n-methylpyrrolidone. During the experiments, feed samples were analyzed with Karl Fischer Titration Method / permeate samples were analyzed with Gas Chromatography. Experiments showed that proper dehydration of aqueous aprotic solvent mixtures was succeded with all three membranes investigated. In the target feed water content range (50 to 20%wt), permeate water contents were higher than 98%wt which was quite acceptable for all membranes. Moreover, NaA zeolite membrane performed higher fluxes than optimized silica and HybSi in composition range of 50 to 15% water at 50oC. It was also observed that HybSi membrane had higher fluxes and permeate water contents than optimized silica membrane for all solvents. On the other hand, the rates of decrease in permeate fluxes changed depending on the type of solvent for optimized silica and HybSi membranes. With both membranes, permeate flux of dimethylformamide decreased much slower than that of n-methylpyyrolidone. Furthermore, the results showed that permeate fluxes of HybSi membrane increased with increasing operation temperature due to the change of solvent activity in mixture. In addition, an Arrhenious type equation was used to describe changes in fluxes with changing temperature. It was also found that activation energy of water for diffusion through HybSi membrane was calculated as 8980 cal/mol.

Dissertation thesis is focused on study of liquid electrolytes for lithium ion batteries. The electrical and physical properties of aprotic electrolytes are observed. The main goal is to increase the fire safety of the batteries. An anhydrous solvents and there blends was investigated. The common used solvents mixtures and new low flammable solvents were used. The common used solvents were used propylene carbonate, ethylene carbonate and others. The new solvents were sulfolane and dimethyl sulfone. In the second part of the work the phosphor base flame retardants as additive in electrolytes was investigated. The last part deals with ionic liquids and there possible use as electrolyte in lithium ion batteries.

The thesis is devoted to the field of properties investigation of new types of electrolytes, and assess the appropriateness of electrolytes studied in this paper for use in Li -ion batteries. It focuses specifically on electrolytes based on aprotic solvents and their mixtures with the flame retardants. The goal of the thesis is to investigate the effects of FRAs on electrolyte mixtures via changes in specific conductivity and freezing point. These objectives were fulfilled by using electrochemical impedance spectroscopy in combination with a cryoscopic measurement method. There were overall 16 samples examined. The samples were prepared as a combination of chemicals, specifically Ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), dimethyl sulfone (DMSO2), triethyl phosphate (TEP) Dimethyl methylphosphonate (DMMP), triphenyl phosphate (TPP). Based on the results of the experiments, the mixtures were sorted according to the observed properties in the tables listed in the last part of this paper. These values can be further used to supplement the continuing research of electrolytes and also as assistance in searching for the new electrolyte mixtures.

The threat of the ongoing climate crisis requires the complete reduction of carbon emissions in the next two to three decades. Carbon dioxide electrochemical reduction (CO₂ER) poses a promising pathway to be able to maintain our current energy infrastructures in a carbon neutral fashion, by allowing the production of fuels and chemicals, such as CO, methanol and ethylene, with the use of carbon capture technologies and green energy. Thus far, Cu is the only metal that has demonstrated the ability to form hydrocarbon products. However, Cu is hindered by low selectivity. Improvements have been observed by coupling Cu with noble metals, such as Ag and Au. However, despite significant advancements, the technology has yet to achieve sufficient performance in activity, stability and selectivity for commercial viability. As such, this work pursued to further advance the activity of CO₂ER through the use of plasmonic Cu-based catalysts and the study of novel dinitrile-based electrolytes. It has recently been identified that CO₂ER can benefit from direct plasmonic effects induced by light illumination. In essence, certain light wavelengths can induce collective oscillations of the free electrons in the metallic particles, leading to an enhancement of their electrocatalytic performance. As such, the first project of this work involved the development and testing of plasmonic Cu-Ag bimetallic catalysts for the application of CO₂ER. Cu, Ag, as well as Cu-Ag bimetallic particles with variable morphologies were able to be synthesized through a facile one-pot sodium borohydride chemical reduction method. The synthesized catalyst performance was also compared to commercial catalysts. The synthesized particles were found to be active catalysts for CO₂ER, with improved electro-catalytic activities exhibited by Cu₈₅Ag₁₅, Cu₆₀Ag₄₀ and Cu syntheses in respective order. All nanoparticles demonstrated increases in the catalytic activity ranging between 15-26% under white light illumination, attributed to plasmonic promotion. The best plasmonic promotion of 26% was observed in the CuAg commercial alloy. Meanwhile, the best promotion of the synthesized bimetallic particles was of 18% found in the Cu₆₀Ag₄₀ catalyst. Additionally, improved electrochemical and plasmonic stability was observed with the use of the Cu-Ag bimetallic synthesized structures compared to monometallic Cu. In addition, most studies pertaining CO₂ER involve aqueous electrolytes due to their low cost and low toxicity. However, these systems are hindered by mass transfer limitations due to the low solubility of CO₂ in water. Organic-based electrolytes have been subjects of research as they possess higher CO₂ solubilities to water. As dinitriles pose a novelty in the role of CO₂ER, dinitrile-based electrolytes were studied and tested for the application. It was hypothesized that due to the decreased polarity in dinitrile solvents, CO₂ concentrations in the electrolyte would increase leading to improved catalytic activity. The testing was conducted by evaluating and comparing acetonitrile (ACN), adiponitrile (ADN) and sebaconitrile (SBN) solvent-based electrolytes. Increased CO₂ solubility was observed in the dinitriles with 582 mM and 503 mM of dissolved CO₂ in ADN and SBN respectively, compared to 270 mM in ACN. Results were corroborated through DFT modelling, indicating preference of CO₂ absorbance to nitrile groups on the molecules. However, despite increases in CO₂ concentration, the electrochemical activity decreased from ACN > ADN > SBN. The trend in activity was observed to be inversely proportional to the viscosity of the dinitrile solvents, which affected the ionic conductivity. Based on these developments, the present thesis opens a new perspective for the use of Cu-based nanoparticles for direct plasmonic enhancement with the use of a broad-range wavelength white light. Furthermore, the work also sheds light on the properties and resulting electrocatalytic activities of the use of dinitrile organic electrolytes for CO₂ER. The presented findings provide significant groundwork for further developments in the realm of CO₂ER.