The synthesis of 2,4,6,8-Tetramethylcyclotetrasiloxane (D4H), and Poly(methylhydrosiloxane) (PMHS) average molecular weight 1700-3200 g/mol, were functionalized with different repeat units of methoxy polyethylene glycol (PEG) (n = 8,12,17). These compounds act as polymer electrolytes with a backbone of siloxane and they were prepared via hydro-silylation reaction to be functionalized with different molecular weights of Ally-PEG. The compounds were confirmed by FT-IR, 1H-NMR and 13C NMR spectroscopy. A hydro-silylation reaction between the functionalized AllyPEG of different molecular weights produced four compounds with a low glass transition temperature that could improve comb like polymer electrolytes conductivity by reducing crystalline phase of PEO. Another way to increase the percentage of the amorphous phase of PEO is to blend it with other polymers. The blending method is considered to be an important method to improve the ionic conductivities and dimensional stability of polymer electrolytes. The main advantages of the blend systems are the simplicity of preparation and the ease to control the physical properties. A high molecular weight of poly 2- vinyl pyridine (Mw=200,000) was added to improve the dimensional stability. Differential scanning calorimetry (DSC) thermal analysis shows that all the blend systems will exhibit an increase in the glass transition temperature by increasing the salt content. The other novel synthesis of polymer electrolytes are triglyme borane and borosilicate. They were synthesized via hydro-boration. These compounds were characterized and confirmed by FT-IR, 1H-NMR 13C NMR spectroscopy. The ionic conductivity of both systems, pure and blend, of different compositions were determined at four temperatures i.e. 25°C, 40°C, 55°C and 70°C. A maximum ionic conductivity value of the siloxane blend is 9.1x10-4 S cm-1 and the pure triglyme borane is 2.14x10-3 S cm-1 at ambient temperature. The ratios of ethylene oxide to lithium salt of siloxane blend and pure triglyme borane were 10:1 and 35:1 respectively. These ratios were the highest conductivity obtained in all the electrolyte systems. The ionic conductivity increases with increasing temperature and salt content to reach optimum concentration. This behavior results in ionic transport, which is supported by the segmental motion of the polymer matrix host.

Polymer electrolytes are the most obvious candidates for safe "all-solid" Li-ion batteries and other electrochemical devices. However, they still have relatively poor ionic conductivities, which limits their wider adoption in commercial applications. It has earlier been the conventional wisdom that only amorphous phases of polymer electrolytes show usefully high ionic conduction, while crystalline forms are insulators. However, this has been challenged in the last decade by the discovery of highly organized, low-dimensional ion-conducting materials. Specifically, the crystalline phases of LiXF6.PEO6 exhibit higher ionic conductivities than their amorphous counterparts, with the Li-ion conduction taking place along the PEO channels. Polymer chain-length and chain-end registry has emerged as potentially significant in determining ionic conduction in these materials. Molecular Dynamics simulations have therefore been made of short-chain, monodisperse (Mw~1000), methoxy end-capped LiPF6.PEO6 to examine relationships between ion conduction and mode of chain-ordering. Studies of smectic and nematic arrangements of PEO chains have revealed that ion-transport mechanisms within the smectic planes formed by cooperative chain-end registry appear to be more suppressed by ion-pairing than in-channel conduction. Disorder phenomena in the chain-end regions emerge as a critical factor in promoting Li-ion migration across chain-gaps, as does the structural continuity of the PEO channels. Simulations incorporating ~1% aliovalent SiF62- dopants further suggest an increase in Li-ion conduction when the extra Li-ions reside within the PEO channels, with the anion influencing charge-carrier concentration through enhanced ion-pair formation. XRD techniques alone are shown to be inadequate in ascertaining the significance of the various short-chain models proposed; atomistic modelling is clearly a helpful complement in distinguishing more or less favourable situations for ion conduction. Though providing valuable insights, it must be concluded that this work has hardly brought us significantly closer to breakthroughs in polymer electrolyte design; the critical factors which will make this possible remain as yet obscure.

La pile à combustible est une solution d'avenir pour produire de l'électricité propre. Cependant des problèmes technologiques limitent pour le moment un déploiement à grande échelle. C’est au cœur de pile et plus particulièrement de la membrane conductrice ionique séparant l’anode et la cathode, que certaines difficultés se posent. Nous pouvons ainsi citer l’impossibilité d’améliorer l’efficacité du catalyseur et le rendement du dispositif en augmentant simplement la température de fonctionnement (100 - 120°C). En effet, la membrane de référence (Nafion) perd ses propriétés thermomécaniques au-delà de 80°C, alors que les membranes alternatives (offrant une meilleure stabilité thermomécanique) sont victimes d’un vieillissement chimique trop rapide qui induit un arrêt inopiné du dispositif. Pour lever ce verrou technologique, nous proposons une nouvelle stratégie qui repose sur le développement de membranes nano-composites constituées d'une matrice ionomère commerciale (non réticulée) dans laquelle nous introduirons des précurseurs aptes à former une phase sol-gel offrant une stabilisation chimique et thermomécanique (réticulée). C'est le contrôle de la chimie de ce réseau, de sa morphologie et de sa localisation dans la membrane hôte qui permettra l'amélioration des propriétés de la membrane hybride ainsi obtenue.Nous avons réalisé une analyse minutieuse de l'effet d’un traitement hydrothermique sur la microstructure des membranes sPEEK. Grâce à cette analyse nous pouvons relier la microstructure avec les propriétés fonctionnelles de l’ionomère pour obtenir des membranes sPEEK mieux nanostructurées et donc plus performantes. Le procédé sol-gel permet la croissance de la phase sol-gel sans perturbation de la nanostructuration initiale de l'ionomère. Cette stratégie permet donc de contrôler la distribution et la morphologie de la phase inorganique.Le processus d'élaboration des membranes hybrides a été étudié. Nous avons étudié l'influence des paramètres de fabrication sur les propriétés des membranes hybrides, et ainsi pu produire des membranes hybrides optimisées. Les propriétés physiques et chimiques de ces membranes ont été évaluées par de nombreuses techniques (SANS, IR, DMA, etc.). L'influence de la structure chimique (degré de réticulation) du réseau sol-gel des membranes hybrides et l'impact de la teneur en sol-gel et de sa distribution (morphologie) dans la membrane hôte sur les propriétés fonctionnelles sont présentés. Nous observons une grande influence du dégrée de réticulation et de la quantité de sol-gel présent dans la membrane qui conditionne les propriétés fonctionnelles de la membrane. / Fuel cell is a promising solution for clean production of hydrogen based energy. However to achieve a large-scale deployment of this technology, issues remain to be addressed. One of the remaining problems concerns the heart of the cell (polymer membrane sandwiched between two electrodes). We can stress the fact that it is impossible to improve the catalyst efficiency and the cell performance by a simple increase of the operating temperature (100-120 °C). Indeed the reference membrane (Nafion) exhibit a step decrease of its thermomechanical properties beyond 80 °C, whereas alternative membranes (with a better thermomechanical stability) are victims of a much faster chemical aging resulting into unexpected failure of the device.Our main objective is to develop novel hybrid membranes consisting of a commercial ionomer matrix in which we will introduce precursors capable to form a sol-gel phase. It will result on membrane composed of two interpenetrating phases, an ion conductive non-crosslinked polymer phase and a crosslinked inorganic phase providing chemical and thermomechanical stabilization. The control of the chemistry of this sol-gel phase, its morphology and its location in the membrane, which will improve the membrane properties, are essential to consider the development of these membranes for fuel cells.A careful analysis of the hydrothermal treatment effect on the microstructure of sPEEK membranes has been performed. Thanks to this analyse we can relate the microstructure with the functional properties of the polymer. The sol-gel process enables the growth of the sol-gel phase without disturbance of the initial nanostructured membrane. This strategy makes possible to control the distribution and morphology of the inorganic phase.The elaboration process of hybrid membrane has been studied. We presented the influence of elaboration parameters regarding the best conditions to prepare an optimized hybrid membrane. The physical and chemical properties of the inorganic phase were evaluated by many techniques (SANS, IR, DMA, etc.). The influence of the chemical structure (cross-linking degree) of the sol-gel network andthe impact of the sol-gel content and its distribution (morphology) into the host membrane on their functional properties is presented. We observed the great influence of cross-linking degree and of the amount of sol-gel present in the membrane which determines the functional properties of the membrane.

Este trabalho teve como objetivo principal a preparação e caracterização de filmes de alginato de sódio plastificado com glicerol. Foram preparadas amostras de filmes variando-se a concentração de ácido acético ou de perclorato de lítio, com a finalidade de otimizá-los como eletrólitos sólidos poliméricos (ESP) em dispositivos eletroquímicos, como sensores e baterias. Após o preparo dos filmes, estes foram caracterizados por análise elementar (AE), microscopia eletrônica de varredura (MEV), difração de raios-X, termogravimetria (TG), análise térmica mecânico dinâmica (DMTA), espectroscopia no UV-VIS, espectroscopia de infravermelho (IR) e espectroscopia de impedância eletroquímica (EIE). Os filmes preparados com alginato de sódio foram plastificados com 0,6 g de glicerol e apresentaram transparência nos comprimentos de onda da luz visível, boa condutividade iônica e maleabilidade. Através dos difratogramas de raios-X pode-se observar que os filmes possuem predominantemente caráter amorfo. O filme de alginato de sódio dopado com 0,3 mL ácido acético apresentou a melhor condutividade (8,7x10-5 S cm-1 a temperatura ambiente e de 1,15x10-3 S cm-1 a 80°C). Para amostras com quantidades maiores de ácido acético os filmes tornaram-se quebradiços e opacos. Para as amostras preparadas com perclorato de lítio a melhor condutividade obtida foi com o filme preparado utilizando 15% em massa de perclorato de lítio: 3,1x10-4 S cm-1 a temperatura ambiente e 1,2x10-3 S cm-1, a 80°C. As análises dos valores de condutividade em função da temperatura das amostras de alginato de sódio revelaram que este segue o modelo Vogel-Tamman-Fulcher (VTF) de condução, onde a movimentação das cadeias poliméricas auxilia na condução iônica. O valor de energia de ativação foi de 36,14 kJ mol-1 para a amostra com 0,3 mL de ácido acético foi de 36 kJ mol-1 para a amostra com 0,4 mL de ácido. Para os filmes preparados com 15% em massa de perclorato de lítio foi de 18,43 kJ mol-1. Essas novas membranas demonstraram ser candidata promissora para aplicação em diversos dispositivos eletroquímicos. / The aim of this study was the preparation and characterization of sodium alginate membranes plasticized with glycerol. The samples were obtained with different concentration of acetic acid or lithium perchlorate in order to use them as solid polymer electrolytes (SPE) in electrochemical devices, such as sensors and batteries. The films were characterized by elemental analysis (EA), scanning electron microscopy (SEM), X-ray, thermogravimetry (TG), dynamic-mechanical thermal analysis (DMTA), UV-visible spectroscopy, infrared spectroscopy (IR) and electrochemical impedance spectroscopy (IES). The samples plasticized with 0.6 g of glycerol showed good transparency, good ionic conductivity and flexibility. X-ray diffractograms evidenced predominantly amorphous state of the samples. The best ionic conductivity results of 8.7 x 10 -5 S cm -1 at room temperature and 1.15 x 10 - 3 S cm -1 at 80 ° C were obtained with sodium alginate samples containing 0.3 mL of acetic acid. Samples with larger amounts of acid became brittle and opaque. The best conductivity values of 3.1 x10 -4 S cm -1 at room temperature and 1, 2 x10 -3 S cm -1 at 80 ° C were obtained for the samples containing 15 wt.% of lithium perchlorate.. The analysis of the conductivity as a function of temperature revealed that they follow the Vogel-Tamman-Fulcher (VTF) conductivity model. The activation energy were 36, 14 kJ mol -1 for the sample with 0.3 mL of acetic acid and 36 kJ mol -1 for the sample with 0.4 mL of acid. The sample with 15 wt.% of lithium perchlorate showed activation energy of 18.43 kJ mol -1. This new ionic conducting membranes are good candidates to be used as electrolytes in electrochemical devices.

No description available.

Este trabalho teve como objetivo principal a preparação e caracterização de filmes de alginato de sódio plastificado com glicerol. Foram preparadas amostras de filmes variando-se a concentração de ácido acético ou de perclorato de lítio, com a finalidade de otimizá-los como eletrólitos sólidos poliméricos (ESP) em dispositivos eletroquímicos, como sensores e baterias. Após o preparo dos filmes, estes foram caracterizados por análise elementar (AE), microscopia eletrônica de varredura (MEV), difração de raios-X, termogravimetria (TG), análise térmica mecânico dinâmica (DMTA), espectroscopia no UV-VIS, espectroscopia de infravermelho (IR) e espectroscopia de impedância eletroquímica (EIE). Os filmes preparados com alginato de sódio foram plastificados com 0,6 g de glicerol e apresentaram transparência nos comprimentos de onda da luz visível, boa condutividade iônica e maleabilidade. Através dos difratogramas de raios-X pode-se observar que os filmes possuem predominantemente caráter amorfo. O filme de alginato de sódio dopado com 0,3 mL ácido acético apresentou a melhor condutividade (8,7x10-5 S cm-1 a temperatura ambiente e de 1,15x10-3 S cm-1 a 80°C). Para amostras com quantidades maiores de ácido acético os filmes tornaram-se quebradiços e opacos. Para as amostras preparadas com perclorato de lítio a melhor condutividade obtida foi com o filme preparado utilizando 15% em massa de perclorato de lítio: 3,1x10-4 S cm-1 a temperatura ambiente e 1,2x10-3 S cm-1, a 80°C. As análises dos valores de condutividade em função da temperatura das amostras de alginato de sódio revelaram que este segue o modelo Vogel-Tamman-Fulcher (VTF) de condução, onde a movimentação das cadeias poliméricas auxilia na condução iônica. O valor de energia de ativação foi de 36,14 kJ mol-1 para a amostra com 0,3 mL de ácido acético foi de 36 kJ mol-1 para a amostra com 0,4 mL de ácido. Para os filmes preparados com 15% em massa de perclorato de lítio foi de 18,43 kJ mol-1. Essas novas membranas demonstraram ser candidata promissora para aplicação em diversos dispositivos eletroquímicos. / The aim of this study was the preparation and characterization of sodium alginate membranes plasticized with glycerol. The samples were obtained with different concentration of acetic acid or lithium perchlorate in order to use them as solid polymer electrolytes (SPE) in electrochemical devices, such as sensors and batteries. The films were characterized by elemental analysis (EA), scanning electron microscopy (SEM), X-ray, thermogravimetry (TG), dynamic-mechanical thermal analysis (DMTA), UV-visible spectroscopy, infrared spectroscopy (IR) and electrochemical impedance spectroscopy (IES). The samples plasticized with 0.6 g of glycerol showed good transparency, good ionic conductivity and flexibility. X-ray diffractograms evidenced predominantly amorphous state of the samples. The best ionic conductivity results of 8.7 x 10 -5 S cm -1 at room temperature and 1.15 x 10 - 3 S cm -1 at 80 ° C were obtained with sodium alginate samples containing 0.3 mL of acetic acid. Samples with larger amounts of acid became brittle and opaque. The best conductivity values of 3.1 x10 -4 S cm -1 at room temperature and 1, 2 x10 -3 S cm -1 at 80 ° C were obtained for the samples containing 15 wt.% of lithium perchlorate.. The analysis of the conductivity as a function of temperature revealed that they follow the Vogel-Tamman-Fulcher (VTF) conductivity model. The activation energy were 36, 14 kJ mol -1 for the sample with 0.3 mL of acetic acid and 36 kJ mol -1 for the sample with 0.4 mL of acid. The sample with 15 wt.% of lithium perchlorate showed activation energy of 18.43 kJ mol -1. This new ionic conducting membranes are good candidates to be used as electrolytes in electrochemical devices.

This work deals with electrolytic conductivity of gel polymer electrolytes. In the theoretical part of the work the methacrylates, the polymerization and the basic outlines of gel polymer electrolytes conductivity are described. The preparation and electrical conductivity of gels based on PMMA are described in the experimental part.

No description available.

Among the myraid energy storage technologies, polymer electrolytes have been widely employed in diverse applications such as fuel cell membranes, battery separators, mechanical actuators, reverse-osmosis membranes and solar cells. The polymer electrolytes used for these applications usually require a combination of properties, including anisotropic orientation, tunable modulus, high ionic conductivity, light weight, high thermal stability and low cost. These critical properties have motivated researchers to find next-generation polymer electrolytes, for example ion gels. This dissertation aims to develop and characterize a new class of ion gel electrolytes based on ionic liquids and a rigid-rod polyelectrolyte. The rigid-rod polyelectrolyte poly (2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT) is a water-miscible system and forms a liquid crystal phase above a critical concentration. The diverse properties and broad applications of this rigid-rod polyelectrolyte may originate from the double helical conformation of PBDT molecular chains. We primarily develop an ionic liquid-based polymer gel electrolyte that possesses the following exceptional combination of properties: transport anisotropy up to 3.5×, high ionic conductivity (up to 8 mS cm⁻¹), widely tunable modulus (0.03 – 3 GPa) and high thermal stability (up to 300°C). This unique platform that combines ionic liquid and polyelectrolyte is essential to develop more advanced materials for broader applications. After we obtain the ion gels, we then mainly focus on modifying and then applying them in Li-metal batteries. As a next generation of Li batteries, the Li-metal battery offers higher energy capacity compared to the current Li-ion battery, thus satisfying our requirements in developing longer-lasting batteries for portable devices and even electric vehicles. However, Li dendrite growth on the Li metal anode has limited the pratical application of Li-metal batteries. This unexpected Li dendrite growth can be suppressed by developing polymer separators with high modulus (~ Gpa), while maintaining enough ionic conductivity (~ 1 mS/cm). Here, we describe an advanced solid-state electrolyte based on a sulfonated aramid rigid-rod polymer, an ionic liquid (IL), and a lithium salt, showing promise to make a breakthrough. This unique fabrication platform can be a milestone in discovering next-generation electrolyte materials. / Ph. D.

This dissertation aims to develop, characterize, and fundamentally understand a new class of materials termed "molecular ionic composites" (MICs). MICs show promise as next-generation solid electrolytes for batteries. MICs form when mixing a rigid polyanion with purely ionic fluids, and they behave mechanically as a solid but contain a high density of ions that move nearly as in a neat liquid. Specifically, prototypical MICs are based on solutions of the rigid-rod polyelectrolyte poly(2,2'-disulfonyl-4,4'-benzideneterephthalamide) (PBDT), which forms a double helix, combined with imidazolium-based ionic liquids (ILs). The IL comprises 75-97 wt% of the final solid, even though the Young's modulus can reach ~ 2 GPa at 80 wt% IL. We propose that these properties are driven by a biphasic internal structure in MICs corresponding to IL-rich "puddles" (an interconnected liquid phase) and PBDT-IL associated "bundles" where IL ions form the collective electrostatic associations that cause the MICs to be a solid. Through this dissertation I will discuss a wide variety of MICs that have been created through the use of two different formation processes, the "ingot" method and the "solvent casting" method, which allow for the use of many different ionic fluid sources to further tune MIC properties. The following chapters build to the fundamental knowledge and our current understanding of the wide variety of materials that can be created from PBDT and IL. / Doctor of Philosophy / Battery electrolytes, biosensors, and hydrogels all depend on new materials for next-generation applications. For these new materials to be used characterization on the interactions, morphological restrictions, and/or what unique internal structures used to generate their properties must be performed. Through This analysis using common polymeric characterization techniques these materials can be further optimized. This dissertation highlights a new class of materials termed "molecular ionic composites" (MICs) which are formed from a rigid double helical polymer, poly(2,2'-disulfonyl-4,4'-benzideneterephthalamide) (PBDT), and fluids composed entirely of ions, including ionic liquids (ILs). These composite systems feature a unique combination of properties including high thermal stability, mechanical stability, and excellent ionic conductivity, all of which are highly tunable through the amount of PBDT incorporated or the fluid ion types. Chapters 3, 4, 5, and 6 present fundamental investigations of MICs to determine how tunable they are, the processes by which they form, and the various ways we can fabricate them. Chapter 7 describes the creation of another impressive material formed from PBDT-low-polymer-content hydrogels. These studies are intended to provide deeper understanding of the behaviors of these unique materials and how they may be used in the future.