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

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

Metal-based high entropy oxides are considered promising electrode materials for use in Li- ion batteries. In this work, the most widely studied high entropy oxide Mg0.2Ni0.2Cu0.2Co0.2Zn0.2O (M-HEO) with rock salt structure was successfully synthesized by Modified Pechini synthesis, characterized by X-ray diffraction analysis, and investigated as anode active material (negative electrode) in a coin cell. M-HEO has the concept of entropy stabilisation of crystal structure in oxide system with the configurational entropy value of 1,6R which confirmed that M-HEO classified as high entropy oxide.  To test the electrochemical performance, full cells comprising M-HEO as anode, lithium manganese oxide (LMO) as cathode together with ionic liquid electrolyte were assembled to explore their potential for practical applications. The electrochemical cycling performance was studied by two electrochemical experiments which are three-electrode cyclic voltammetry and galvanostatic charge/discharge. The cyclic voltammetry measurement was used to determine the behaviour of the system such as potential window and scan rate, while galvanostatic charge/discharge was used to determine the performance of the battery over time by applying constant current.  The results demonstrate that high entropy oxide possess a stable structure. This points out the direction for the preparation of M-HEOs with stable structure and excellent performance and provides a promising candidate for anode materials for LIBs. / Metallbaserade högentropioxider anses vara lämpliga för användning av elektrodmaterial för litium-jon batterier. I detta arbete syntetiserades den första högentropioxiden Mg0.2Ni0.2Cu0.2Co0.2Zn0.2O (M-HEO) som har stensaltstruktur genom Modifierad Pechini- syntesmetod, karakteriserad av röntgendiffraktionsanalys och undersöktes som aktivt material i den negativa elektroden. M-HEO har konceptet av entropistabilisering av kristallstrukturen i oxidsystem som har det konfigurerade entropivärdet av 1,6R. Detta bekräftade att M-HEO klassificerades som högentropioxid.  För att testa den elektrokemiska prestandan, användes fullceller bestående av M-HEO som anod, litiummanganoxid (LMO) som katod tillsammans med jonisk flytande elektrolyt. Detta gjordes för att undersöka M-HEO potentiella praktiska tillämpningar. Den elektrokemiska cyklingsprestandan studerades genom två elektrokemiska experiment, cyklisk voltammetri med tre-elektroder och galvanostatisk laddning/urladdning med knapp-celler. Den cykliska voltammetri mätningen användes för att bestämma vart i systemet sker redox reaktion för att sedan kunna identifiera på vilka potentialintervall samt skanningshastighet, medan galvanostatisk laddning/urladdning användes för att bestämma batteriets prestanda över tid genom att applicera konstant ström. Resultaten visar sig att hög entropi oxider har en stabil stensaltstruktur. Detta bidrar till att M-HEO som har en stabil struktur kan vara ett lämpligt anodmaterial i litium-jon batterier.

This thesis project was executed at ABB AB. The purpose of the thesis was to formulate aselection of ionic liquids with different thickeners as greases and experimentally understand thetribological characteristics and electrical properties. The performance of four ionic liquids, 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (IL6), 1-Butyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)imide (IL2), 1-Hexyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)imide (IL3), and 1-Hexyl-1-methylpyrrolidiniumbis(trifluoromethylsulfonyl)imide (IL4) and two thickeners, polytetrafluoroethylene (PTFE)powder and lithium stearate were evaluated for tribological and electrical properties. Two ionicliquids, 1-Ethyl-3-methylimidazolium dicyanamide, 1-Butyl-3-methylimidazolium dicyanamidefailed to form stable greases due to poor miscibility with the thickeners. Frictional tests for all thecomposed grease were performed and afterwards analyzed with a light optical microscope forassessment of the wear tracks. Electrical conductivity was measured with a contact resistancetest setup. Moreover, the dropping point for the greases was measured to ensure theformulations were qualified as lubricant greases. Ionic liquid greases containing PTFE as athickener show better thermal stability than those containing lithium stearate. In regards to antiwearand friction reduction, the results indicate better tribological properties for the IL3 and IL4with the 25 wt% of PTFE and lithium stearate. The electrical conductivities were similar for allthe ionic liquid grease formulations which were higher than the general purpose grease as thereference. The work has paved the way for further investigation of ionic liquid based greaseswhich show potential in mitigation of bearing current in electric machines.

The pursuit of reliable and high-performance batteries has fueled extensive research into new battery chemistries and materials, aiming to enhance the current lithium-ion battery technologies in terms of energy density and safety. Among the potential advancements, solid-state batteries (SSBs) have captured significant attention as the next-generation energy storage technology. One key factor contributing to their appeal is the utilization of solid-state electrolytes (SSEs) with a wide electrochemical stability window (ESW), making SSBs compatible with high-voltage cathodes. The energy density of SSBs can be further improved by employing the “holy-grail” anode, Li-metal, which boasts the lowest working voltage (-3.04 V vs. Li+/Li) and an ultrahigh theoretical capacity (3860 mAh g−1). Consequently, these batteries are referred to as lithium metal batteries (LMBs). However, realizing the full potential of LMBs presents formidable challenge, including the low ionic conductivity of current SSEs, large interfacial resistance between SSE and electrodes, uncontrollable interfacial reactions, and the growth of Li dendrites.  Typically, SSEs can be categorized into three types. Among these, solid composite electrolytes (SCEs) are considered the most promising choice for solid-state LMBs due to their combination of high ionic conductivity and excellent mechanical strength from inorganic solid electrolytes (ISEs) and the flexibility and good interface compatibility provided by solid polymer electrolytes (SPEs). Polymeric ionic liquids (PolyILs), which contain both ionic liquid-like moieties and polymer frameworks, have emerged as highly attractive alternatives to traditional polymers in SCEs.  The overall objective of this thesis was to develop PolyIL-based SCEs with enhanced ionic conductivity, wide ESW, high Li+ transference number, and reduced electrodes/electrolyte interface resistance. The main progress achieved in this thesis is as follows: 1. We selected three F-based Li-salts to prepare SPEs using poly(ethylene oxide) and polyimide. The investigation focused on assessing the impact of molecular size, F content, and chemical structures (F-connecting bonds) of these Li-salts. Additionally, we aimed to uncover the formation process of LiF in the solid electrolyte interphase (SEI). The result revealed that the F-connecting bond plays a more significant role than the molecular size and F element content, resulting in slightly better cell performance using LiPFSI compared to LiTFSI and substantially better performance compared to LiFSI. The preferential breakage of bonds in LiPFSI was found to be related to its position to Li anode. Consequently, we proposed the LiPFSI reduction mechanism based on these findings. 2. Using the template method, we synthesized a monolayer SCE with enhanced Li+ transference number and high ionic conductivity. In this study, boron nitride (BN) nanosheets with a high specific surface area and richly porous structure were employed as inert inorganic filler. These BN nanosheets played a crucial role in homogenizing the Li+ flux and facilitating the Li+ transmission to suppress Li dendrite growth. When integrated into a LiFePO4//Li cell with the optimized SCE, the assembled battery demonstrated remarkable cycling performance.  3. A monolayer GSCE with multifunctionality was synthesized via a natural sedimentation and subsequent UV-curing polymerization technique. This innovative method capitalizes on intrinsic gravity, allowing for the integration of multiple functions within a single layer, thereby eliminating the additional interlayer resistance. The developed GSCE provides an optimum Li+ transportation path and enhanced Li+ transference number, leading to an enhanced ionic conductivity and a long cycle life of Li//Li cells and SSLMBs. Compared with the monolayer uniform SCEs, the gradient structure also alleviates the uncoordinated thermal expansion between fillers and PolyIL, avoiding increased stress during the cycle and battery capacity fade.

The use of ionic liquids (ILs) as both reagents and solvents is widely recognised. ILs offer a number of advantages compared to regular molecular solvents. These advantages include: chemical and thermal stability, no measurable vapour pressure, no or lower toxicity, non-flammability, catalytic ability, high polarity and they can be recycled. There are a number of research groups investigating the various applications of this reaction medium and most studies have focused on solvents derived from the imidazolium cation. The use of the imidazolium-based ILs in the Diels-Alder reaction has been studied in detail and higher yields compared to conventional methods have been reported. The IL affects the rate and interesting selectivities have been observed. However, not much attention has been paid to the scope and limitations of phosphonium ILs (PILs). Therefore the focus of this thesis is the synthesis and application of novel chiral PILs as environmentally benign, task-specific solvents for the Diels-Alder reaction. In addition, this research seeks alternative ways to eliminate the use of toxic heavy metal catalysts and to exploit methodologies which reduce the energy consumption of the Diels-Alder reaction. A series of CILs were synthesised from the chiral pool and they were characterised by thermogravimetric analysis, differential scanning calorimetry and spectroscopy. They were then investigated as solvents and catalysts in the Diels-Alder reactions of a series of dienes (cyclopentadiene, isoprene, 2,3-dimethylbuta-1,3-diene, furan, pyrrole, N-methyl pyrrole) and dienophiles (methyl acrylate, methyl vinyl ketone, acrylonitrile, dimethyl maleate, acrolein, dimethylacetylene dicarboxylate, maleic anhydride and maleimide). Investigation of the effect of PILs in the presence of three heterogeneous catalysts Al2O3, SiO2 and K-10 montmorillonite were studied. Ultrasound and microwave-assisted Diels-Alder reactions in the PILs, in the absence and presence of the catalysts, were also studied. The reactions of these prototypical substrates illustrated that the solvents are indeed task-specific. / University of Bradford

In this work, the development of parameters for a series of imidazolium-based ionic liquids molecules, now included in the AMOEBA force field, is discussed. The quality of obtained parameters is tested in a variety of calculations to reproduce structural, thermodynamic, and transport properties. First, it is proposed a novel method to parameterize in a faster, and more efficient way parameters for the AMOEBA force field that can be applied to any imidazolim-based cation. Second, AMOEBA-IL polarizable force field is applied to study the N-tert-butyloxycarbonylation of aniline reaction mechanism in water/[EMIM][BF4] solvent via QM/MM approach and compared with the reaction carried out in gas-phase and implicit solvent media. Third, AMOEBA-IL force field is applied in alchemical calculations. Free energies of solvation for selected solutes solvated in [EMIm][OTf] are calculated via BAR method implemented in TINKER considering the effect of polarization as well as the methodology to perform the sampling of the alchemical process. Finally, QM/MM calculations using AMOEBA to get more insights into the catalytic reaction mechanism of horseradish peroxidase enzyme, particularly the structures involved in the transition from Cp I to Cp II.

Silicone stands as an indispensable material for numerous applications; however, its high energy-cost synthesis poses significant environmental challenges. To address these concerns, bio-based silicone has gained considerable attention, showcasing its potential to dilute energy density while offering inherent functional benefits. Despite promising prospects, existing incorporation methods often involve protecting groups, rare metal catalysts, and multistep synthesis, which contradict green chemistry principles. The aza- Michael reaction emerges as a superior choice due to its high atom economy and mild reaction conditions. However, it still suffers from prolonged reaction times, hindering its overall efficiency and sustainability. This thesis utilizes self-activated beta-hydroxy acrylates to greatly enhance aza-Michael kinetics, achieving a 3-fold rate enhancement in solvent-free silicone synthesis. This fast aza-Michael reaction acts as the platform for the incorporation of Vitamin C and amino acids into silicone materials. Vitamin C-modified silicone demonstrates the potential for controlled antioxidant activity release, while amino acid-functionalized silicones are synthesized using choline amino acid ionic liquids, presenting a protecting-group-free and solvent-free synthesis method. Moreover, the synthesized choline amino acid-functional polymers and elastomers are investigated for their dielectric properties revealing promising potential for dielectric elastomer actuator applications. These innovative methods offer green alternatives for incorporating hydrophilic biomolecules into hydrophobic silicone systems, providing new functionalities that address both environmental and functional requirements. / Thesis / Doctor of Science (PhD)

Since their introduction by Sony in 1990, lithium-ion batteries (LIBs) have acquired a sizable market share. They have the best energy densities, a high open circuit voltage, a low self-discharge rate, no memory effect, and a slow loss of charge when not in use. These properties make them the most popular rechargeable batteries for portable gadgets, electric vehicles and aerospace applications.  They do, however, pose major safety issues since the electrolytes are made up of fluorinated salts dissolved in volatile organic solvents, the former being meta-stable at ambient temperature and the latter being flammable a with high vapour pressure. Thus, there is an urge to develop thermally and electrochemically stable non-fluorinated electrolytes to improve the safety and performance of batteries. Electrolytes based on ionic liquids (ILs) in general offer a range of suitable advantages including low volatility and high thermal and electrochemical stabilities,and can additionally be made fluorine-free. In general, their physicochemical properties are determined by the interactions between the cations and anions, which are controlled by the chemical functionalities present, with vast freedom in structural design to reduce these interactions and enhance also the ion mobilities.  In this study, favoring from of “structural design” three different families of fluorine-free ionic liquids-based electrolytes are designed and created. These families of ILs comprising n- tetrabutylphosphonium, imidazolium, pyridinium based cations and pyridine, pyrazine and ether functionalized salicylate-based anions. The structures and purity of these new ILs are characterized by using multinuclear NMR, FTIR and mass spectrometry. Several features and properties of the novel electrolytes are investigated; thermogravimetric analysis, differential scanning calorimetry, ionic conductivity and electrochemical stability. These studies are further complemented by using PFG NMR diffusometry to understand the possible interaction mechanisms between the oppositely charged ions within the electrolytes, and especially, the influence of Li+ addition in the IL-based electrolytes.

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