yes / Controlling polymer thin-film morphology and crystallinity is crucial for a wide range of applications, particularly in thin-film organic electronic devices. In this work, the crystallization behavior of a model polymer, poly(ethylene oxide) (PEO), during spincoating is studied. PEO films were spun-cast from solvents possessing different polarities (chloroform, THF and methanol) and probed via in situ grazing incidence wide angle x-ray scattering. The crystallization behavior was found to follow the solvent polarity order (where chloroform < THF < methanol) rather than the solubility order (where THF > chloroform > methanol). When spun-cast from non-polar chloroform, crystallization largely followed Avrami kinetics, resulting in the formation of morphologies comprising large spherulites. PEO solutions cast from more polar solvents (THF and methanol) do not form well-defined highly crystalline morphologies and are largely amorphous with the presence of small crystalline regions. The difference in morphological development of PEO spun-cast from polar solvents is attributed to clustering phenomena that inhibit polymer crystallization. This work highlights the importance of considering individual components of polymer solubility, rather than simple total solubility, when designing processing routes for the generation of morphologies with optimum crystallinities or morphologies.

Poly (glycerol-sebacate) (PGS) is a synthetic bioelastomer with a covalently crosslinked, three-dimensional network of random coils with hydroxyl groups attached to its backbone. This biodegradable polymer is biocompatible (in vitro and in vivo), tough, elastic, inexpensive, and flexible, and finds potential applications in tissue engineering and regenerative medicine. Due to the slow rate of step-growth polymerisation, the synthesis of PGS prepolymer requires 24-48 h. A batch and a continuous process, if developed, could address the inherent deficiencies (eg. long residence time, venting) associated with the large-scale synthesis of such bioelastomers. However, in order to assess whether this particular system may be adapted to continuous processes, such as reactive extrusion, studies on kinetics of controlled condensation reactions are of vital importance. FT-Raman spectroscopy was used to study the kinetics of the step-growth reactions between glycerol (G) and sebacic acid (SA) at three molar ratios (G:SA= 0.6,0.8,1.0) and three temperatures (120, 130, 140 ˚C). The rate curves followed first-order kinetics with respect to sebacic acid concentration in the kinetics regime. An increase in the molar ratio (G : SA) of the reactants decreased the average functionality of the system and the crosslinking density, resulting in the lowering of the activation energy and pre-exponential factor. The average functionality of the system had a profound effect on the crosslinking density, mechanical properties, and the reaction kinetics of the system. Three different PGS oligomers and films (PGS 0.6, PGS 0.8, PGS 1.0) were thoroughly characterised using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), wide angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), and contact angle measurements. FTIR spectra of PGS oligomers confirmed the formation of ester bonds (1740 cm -1). Quantification of various functional groups in PGS films using XPS was in agreement with the theoretical values of the proposed structure. WAXS results indicated that PGS system with a higher average functionality possesses a higher degree of crystallinity. Crystallisation exotherms and melting endotherms of PGS systems revealed that the average functionality influences the density of crosslinking, degree of crystallinity, and the network structure of bioelastomers. Contact angle studies confirmed that an increase in the average functionality of PGS system increases hydrophilicity, and the surface treatment through aminolysis further increases the hydrophilicity of the films. Batch studies were performed on a Brabender Plasticorder®. The samples collected over a reaction period of 5 h were characterised using Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The number-average molecular weight (Mn) and the weight-average molecular weight (Mw) of the oligoesters were determined using matrix-assisted laser desroption/ionization time-of-flight spectroscopy (MALDI-TOF) and compared with the corresponding values from the benchtop synthesis. It was found that due to higher shear-mixing and better orientation of functional groups, the degree of polymerisation at any stage of the reaction was higher in the Brabender than in the benchtop process. The gel-point of the reaction was determined from the crossover point of storage and loss moduli, and the reaction rate constant was calculated using the torque vs time data of the rheometer. The kinetics rate constant and the extent of the reaction in the Brabender were found to be higher than the corresponding values obtained from the conventional benchtop process by a factor of 2. PGS was found to be thermo-mouldable and adaptable to high-shear mixing, and hence is a better candidate for making thermoplastic elastomers using reactive extrusion. The challenges and possibilities in scaling up a batch process to a continuous process were investigated. The use of a wiped film reactor or a disk reactor along with reactive extrusion and batch-mixing (as a post-extrusion operation) is a commercially viable method to synthesise PGS oligomers. Such a continuous process will boost the production of bioelastomers for tissue engineering application by addressing the constraints in step-growth polymerisation. Finally, the effect of PGS substrate stiffness and surface treatment (aminolysis, hydrolysis, layer-by-layer deposition) on the morphology and lineage of mesenchymal stem cells – which have a capacity to differentiate themselves into cartilage, adipose, tendon, and muscle tissues – was analysed using fluorescence microscopy and DNA and protein assays. Stiffness of the PGS surface and the method of treatment influenced the cell attachment and spreading on different surfaces. However, cells did not differentiate into definite phenotypes at the end of 14 d time-point, indicating that higher time-points are needed to be considered to study the effect of matrix stiffness and surface treatment on cell attachment and phenotype differentiation.

The aim of this work was the generation of carbon materials with high surface area, exhibiting a hierarchical pore system in the macro- and mesorange. Such a pore system facilitates the transport through the material and enhances the interaction with the carbon matrix (macropores are pores with diameters > 50 nm, mesopores between 2 – 50 nm). Thereto, new strategies for the synthesis of novel carbon materials with designed porosity were developed that are in particular useful for the storage of energy. Besides the porosity, it is the graphene structure itself that determines the properties of a carbon material. Non-graphitic carbon materials usually exhibit a quite large degree of disorder with many defects in the graphene structure, and thus exhibit inherent microporosity (d < 2nm). These pores are traps and oppose reversible interaction with the carbon matrix. Furthermore they reduce the stability and conductivity of the carbon material, which was undesired for the proposed applications. As one part of this work, the graphene structures of different non-graphitic carbon materials were studied in detail using a novel wide-angle x-ray scattering model that allowed precise information about the nature of the carbon building units (graphene stacks). Different carbon precursors were evaluated regarding their potential use for the synthesis shown in this work, whereas mesophase pitch proved to be advantageous when a less disordered carbon microstructure is desired. By using mesophase pitch as carbon precursor, two templating strategies were developed using the nanocasting approach. The synthesized (monolithic) materials combined for the first time the advantages of a hierarchical interconnected pore system in the macro- and mesorange with the advantages of mesophase pitch as carbon precursor. In the first case, hierarchical macro- / mesoporous carbon monoliths were synthesized by replication of hard (silica) templates. Thus, a suitable synthesis procedure was developed that allowed the infiltration of the template with the hardly soluble carbon precursor. In the second case, hierarchical macro- / mesoporous carbon materials were synthesized by a novel soft-templating technique, taking advantage of the phase separation (spinodal decomposition) between mesophase pitch and polystyrene. The synthesis also allowed the generation of monolithic samples and incorporation of functional nanoparticles into the material. The synthesized materials showed excellent properties as an anode material in lithium batteries and support material for supercapacitors. / Kohlenstoffmaterialien finden aufgrund ihrer Vielseitigkeit heute in den unterschiedlichsten Bereichen des täglichen Lebens ihren Einsatz. Bekannte Beispiele sind Kohlenstofffasern in Verbundwerkstoffen, Graphit als trockenes Schmiermittel, oder Aktivkohlen in Filtersystemen. Ferner wird Graphit als Elektrodenmaterial auch in Lithium-Ionen-Batterien verwendet. Wegen knapper werdender Ressourcen von Öl und Gas wurde in den letzten Jahren verstärkt an der Entwicklung neuer Materialien für die Speicherung von Wasserstoff und elektrischer Energie gearbeitet. Die Nanotechnologie ist dabei auch für neue Kohlenstoffmaterialien zukunftsweisend, denn sie stellt weitere Anwendungsmöglichkeiten in Aussicht. In dieser Arbeit wurden hierzu mittels des sogenannten Nanocastings neue Kohlenstoffmaterialien für Energieanwendungen, insbesondere zur Speicherung von elektrischer Energie entwickelt. Die Eigenschaften eines Kohlenstoffmaterials beruhen im Wesentlichen auf der Struktur des Kohlenstoffs im molekularen Bereich. Die in dieser Arbeit hergestellten Materialen bestehen aus nichtgraphitischem Kohlenstoff und wurden im ersten Teil der Arbeit mit den Methoden der Röntgenstreuung genau untersucht. Eine speziell für diese Art von Kohlenstoffen kürzlich entwickelte Modellfunktion wurde dazu an die experimentellen Streubilder angepasst. Das verwendete Modell basiert dabei auf den wesentlichen Strukturmerkmalen von nichtgraphitischem Kohlenstoff und ermöglichte von daher eine detaillierte Beschreibung der Materialien. Im Gegensatz zu den meisten nichtgraphitischen Kohlenstoffen konnte gezeigt werden, dass die Verwendung von Mesophasen-Pech als Vorläufersubstanz (Precursor) ein Material mit vergleichsweise geringem Grad an Unordnung ermöglicht. Solch ein Material erlaubt eine ähnlich reversible Einlagerung von Lithium-Ionen wie Graphit, weist aber gleichzeitig wegen des nichtgraphitischen Charakters eine deutlich höhere Speicherfähigkeit auf. Zur Beschreibung der Porosität eines Materials verwendet man die Begriffe der Makro-, Meso-, und Mikroporen. Die Aktivität eines Materials kann durch die Erhöhung der Oberfläche noch erheblich gesteigert werden. Hohe Oberflächen können insbesondere durch die Schaffung von Poren im Nanometerbereich erzielt werden. Um die Zugänglichkeit zu diesen Poren zu steigern, weist ein Material idealerweise zusätzlich ein kontinuierliches makroporöses Transportsystem (Porendurchmesser d > 50 nm) auf. Solch eine Art von Porosität über mehrere Größenordnungen wird allgemein als „hierarchische Porosität“ bezeichnet. Für elektrochemische Anwendungen sind sogenannte Mesoporen (d = 2 – 50 nm) relevant, da noch kleinere Poren (Mikroporen, d < 2 nm) z.B. zu einer irreversiblen Bindung von Lithium- Ionen führen können. Wird Mesophasen-Pech als Kohlenstoffprekursor verwendet, kann die Entstehung dieser Mikroporen verhindert werden. Im zweiten und dritten Teil der Arbeit konnte mit den Methoden des „Nanocastings“ zum ersten Mal die spezielle Struktur des Mesophasen-Pech basierenden Kohlenstoffmaterials mit den Vorteilen einer hierarchischen (makro- / meso-) Porosität kombiniert werden. Im ersten Syntheseverfahren wurde dazu ein sogenanntes „hartes Templat“ mit entsprechender Porosität aus Siliziumdioxid repliziert. Aufgrund der hohen Viskosität des Pechs und der geringen Löslichkeit wurde dazu ein Verfahren entwickelt, das die Infiltration des Templates auch auf der Nanometerebene ermöglicht. Das Material konnte in Form größerer Körper (Monolithen) hergestellt werden, die im Vergleich zu Pulvern eine bessere technische Verwendung ermöglichen. Im zweiten Syntheseverfahren konnte die Herstellung eines hierarchisch makro- / mesoporösen Kohlenstoffmaterials erstmals mittels eines weichen Templates (organisches Polymer) erreicht werden. Die einfache Entfernung von weichen Templaten durch eine geeignete Temperaturbehandlung, macht dieses Verfahren im Vergleich zu hart templatierten Materialien kostengünstiger und stellt eine technische Umsetzung in Aussicht. Desweiteren erlaubt das Syntheseverfahren die Herstellung von monolithischen Körpern und die Einbindung funktionaler Nanopartikel. Die hergestellten Materialien zeigen exzellente Eigenschaften als Elektrodenmaterial in Lithium-Ionen-Batterien und als Trägermaterial für Superkondensatoren.

京都大学 / 0048 / 新制・課程博士 / 博士(人間・環境学) / 甲第22708号 / 人博第958号 / 新制||人||227(附属図書館) / 2020||人博||958(吉田南総合図書館) / 京都大学大学院人間・環境学研究科相関環境学専攻 / (主査)教授 内本 喜晴, 教授 高木 紀明, 教授 中村 敏浩 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DFAM

Perovskite solar cells have garnered significant interest thanks to the impressive rise of their efficiency over the last few years to a power conversion efficiency (PCE) of 25.2% despite being processable using cheap and potentially high-throughput solution coating techniques. Using the two-step conversion process high-quality perovskite films with high quality and uniformity can be produced, however, this process still needs a deeper and fundamental understanding. This thesis has shed light on the ink-to-solid conversion during the two-step solution process of hybrid perovskite formulations. We demonstrated that the conversion of PbI2 to perovskite is largely dictated by the state of the PbI2 precursor film in terms of its solvated states. We used several in situ diagnostic measurments such as grazing incidence wide-angle x-ray scattering (GIWAXS), quartz crystal microbalance with dissipation monitoring (QCM-D), and optical reflectance and absorbance all performed during spin coating, to monitor the nucleation and growth of crystalline phases, the mass deposition at the solid-liquid interface and the rigidity as well as the solution thinning behavior and the changes in optical absorbance of the precursor and perovskite. We compare conversion behaviors from different lead states by using methylammonium iodide (MAI), formamidinium iodide (FAI), and/or mixtures of halides (I, Br) and show that conversion can occur spontaneously and quite rapidly at room temperature without requiring further thermal annealing. We confirm this by demonstrating improvements in the morphology, microstructure and optoelectronics properties of the resulting perovskite films, as well as their impact on the PCE of solar cells using complimentary measurements such as scanning electron microscopy (SEM), X-ray diffraction (XRD) and with steady-state photoluminescence.

No description available.

Notre étude a porté sur la compréhension microscopique des mécanismes de déformation du polyamide 6 (PA6) à l’état massif. Par des traitements thermiques appropriés, on a obtenu un jeu d’échantillons présentant des microstructures semi-cristallines variées, avec différentes formes cristallographiques (allotropes : α, γ ou β), différents taux de cristallinité (de 24 à 35%), différentes périodes de l’empilement des lamelles cristallines (de 7 à 12nm), ceci pour deux masses moléculaires différentes. Les propriétés mécaniques en traction ont été caractérisées au-dessus et au-dessous de la transition vitreuse de la phase amorphe (Tg). Les différents matériaux présentent des différences notables de comportements. Le taux de cristallinité semble être le facteur prédominant au-dessus de Tg, mais d’autres facteurs sont à prendre en compte en dessous de Tg, comme la forme cristalline et la morphologie lamellaire (épaisseur et facteur de forme). Grâce à un dispositif expérimental fabriqué sur mesure, des essais de traction ont été suivis par diffusion des rayons X aux petits (SAXS) et grands angles (WAXS) sur la ligne D2AM, ESRF, pour caractériser les déformations à l’échelle des empilements lamellaires et à l’échelle de la maille cristalline. Dans les échantillons présentant principalement de la phase cristalline β, les lamelles tendent à s’orienter perpendiculairement à la direction de traction (TD). Ce mécanisme d’orientation local (que nous appelons « modèle de réseau de chaînes ») est induit par la transmission des contraintes par les chaînes amorphes reliant les lamelles cristallines adjacentes. L’allongement local est plus faible que l’allongement macroscopique dans les lamelles perpendiculaire à TD, ce qui implique que les lamelles inclinées doivent être cisaillées. De plus, la phase β se transforme en phase α aux fortes extensions. Dans les échantillons présentant principalement de la phase α (la plus rigide), au-dessus de Tg, dans le régime élastique, les chaînes tendent d’abord à s’orienter perpendiculairement à TD, ce qui implique que les lamelles s’orientent parallèlement à TD (« modèle de lamelles rigides »). Ensuite, dans le régime plastique, une majeure partie des lamelles se réoriente perpendiculairement à TD, comme dans le « modèle de réseau de chaînes », tandis qu’une fraction mineure reste orientée parallèlement à TD. Une morphologie fibrillaire fortement orientée est finalement obtenue pour tous les échantillons quelle que soit la température. / Mechanical properties of bulk polyamide 6 (PA6) have been studied in relation to microscopic deformation mechanisms. By applying various thermal treatments, sets of samples with different semi-crystalline microstructures, namely various crystalline allotropic forms (denoted α, γ and β) and different values of the crystallinity index (from 24 to 35%) and of the long period of the lamellar stacks (from 7 to 12 nm), have been obtained, for two different molecular masses. Mechanical properties have been measured in the linear (viscoelastic) and nonlinear (plastic) regimes below and above the glass transition of the amorphous phase (Tg). Differences of behavior have been observed depending on the microstructure. While the crystallinity index seems to be the predominant factor affecting the mechanical behavior above Tg, other structural parameters such as the crystalline form and the lamellar morphology (thickness and aspect ratio) have to be taken into account below Tg. Deformations at the scales of lamellar stacks and of the crystalline unit cell have been characterized by small and wide angle X-ray scattering (SAXS and WAXS) performed in-situ during tensile tests. In samples with predominantly β phase, lamellae tend to orient perpendicular to the tensile direction (TD). This orientation mechanism (which we denote as ‘Chain Network model’) is driven by the amorphous chains which transmit the stress between adjacent lamellae. The tensile strain in lamellar stacks perpendicular to TD is lower than the macroscopic tensile strain, which must be compensated by increased shear in inclined stacks. Also, at high extension ratios, the β phase transforms into α phase. In samples with predominantly α phase and above Tg, morphology changes are more complex. In a first step, chains orient perpendicular to TD, which implies that lamellar planes tend to orient parallel to TD, possibly due to their high aspect ratio (denoted as ‘Rigid Lamella’ model). In a second step, beyond the yield, a major fraction of crystallites then reorients normal to TD, i.e. chains themselves become parallel to TD, while a minor fraction remains oriented along TD. A highly oriented fibrillar morphology is ultimately obtained in all cases.

The aim of submitted diploma thesis is the study of non-isothermal crystallization kinetics of polylactide (PLA) with selected agents (1 %) and observation of the emerging crystalline structure under polarizing optical microscope. The agents were talc, a mixture of organic salts with the addition of amorphous SiO2 (HPN 68L) and zinc stearate (HPN 20E) and LAK-301 (potassium salt of 5-dimethylsulfoisophtalate), which is a nucleating agent developer for PLA. The PLA matrix served as a reference. Non-isothermal crystallization took place on a differential scanning calorimeter at cooling rates () 0,3; 0,5; 0,7; 1; 1,5; 2 °C/min After non-isothermal crystallization, the crystalline fraction (Xc) od PLA was evaluated from X-ray diffraction analysis, and the supramolecular structure was observed after chemical degradative etching using confocal laser scanning microscope. The crystallization kinetics were evaluated by the methods of Jeziorny and Mo and the activation energy of the crystallization was determined according to the Friedmann method. All prepared materials were amorphous (Xc 40 % for up to 1,5 °C/min). However, for LAK-301, Xc decreased to 30 % already at the = 2 °C/min and it can be assumed that with increasing its nucleation activity will decrease. A spherulitic structure was observed in all samples, but the number and size of spherulites decreased with increasing and the appearance varied according to the type of agent. Both kinetic models proved to be unsuitable for materials with low Xc and the highest because the rate of crystallization did not change. With the Jeziorny method, it was possible to evaluate the kinetics only for the relative crystallinity Xt = 29–50 % and with the Mo method it was not possible to evaluate the data for the highest for PLA matrix and sample with HPN 68L. The samples with LAK-301 and HPN 68L showed the lowest activation energy.

Ce travail de thèse a visé la préparation de matériaux biohybrides à base de poly (liquide ionique)s (PIL) et de polysaccharide, en l’occurrence la gomme de guar. Les chaînes de poly (1- [2-acryloyl éthyl] -3 bromure-méthylimidazolium (poly (AEMIBr)) ont été synthétisées par polymérisation contrôlée de type RAFT. Des homopolymères de DP élevé (jusqu'à 300) et de faible dispersité (inférieur à 1,19) ont été obtenus seulement en quelques heures dans l'eau. Ces PIL ont par ailleurs été utilisés comme macroagents de transfert pour générer différents copolymères à blocs en milieu homogène et en émulsion dans le but d’accéder à des nano objets autoassemblés. En effet, différentes morphologies ont été obtenues en s’appuyant sur lesconcepts de la PISA. De plus, des copolymères greffés de type guar-g-PIL ont finalement été construits en milieu liquide ionique.en utilisant des dérivés de guar macroagents de transfert Les PIL combinent à la fois les propriétés des IL (non-volatile, stabilité thermique et chimique, haute conductivité...) et celles des polymères en termes de renforcement mécanique, c’est pourquoi ils ont été exploités pour élaborer des matériaux biohybrides de haute performance. La stratégie envisagée dans ce travail réside sur l’exploitation de trois composants: (i) les chaînes de poly (AEMIBr), (ii) le guar et (iii) un liquide ionique: le chlorure de butylméthylimidazolium (BMIMCl). La voie expérimentale permettant l’obtention de tels matériaux est très simple et non dégradante puisqu’elle n’implique que des étapes de solubilisation de polymères en milieu IL. Les propriétés rhéologiques et thermiques de ces matériaux ont été évaluées. En outre, la morphologie interne, par des mesures de WAXS et SAXS, ainsi que le transport ionique ont été étudiés. Il en ressort que de multiples interactions synergiques sont formées entre le guar et les chaînes de PIL, en parallèle des interactions de type PIL/IL et guar/IL. Des ionogels possédant un haut module élastique (jusqu'à 30 000 Pa) et une stabilité thermique élevée (jusqu'à 310 °C) ont ainsi été obtenus. En particulier, la présence de PIL a permis d’améliorer de façon considérable la stabilité dimensionnelle des gels, en limitant complétement les phénomènes d’exudation rencontrés dans les systèmes binaires guar/IL. Il s’avère, de plus, que ces matériaux sont parfaitement homogènes à l’échelle d’observation des analyses SAXS et WAXS. Ces gels ioniques présentent d'excellentes propriétés de transport ionique (10-4 S/cm à 30 °C) grâce notamment à leur structuration interne continue. Cette famille des matériaux multicomposants à base de guar, présente un fort potentiel, notamment pour une utilisation en tant que gel électrolyte dans le domaine de l’énergie. / This Ph.D work focuses on the preparation of biohybrid materials based on poly(ionic liquid)s (PIL) and a polysaccharide, guar gum. Poly(1-[2-acryloylethyl]-3-methylimidazolium bromide (poly(AEMIBr)) chains were synthesized through RAFT polymerization. Homopolymers with DP up to 300 and dispersity below 1.19 were obtained within hours in water. High chain-end fidelity further allowed for PIL chain extension with various monomers and stable PIL-based nanoparticles with various morphologies using the PISA concept were achieved. A series of guar-g-PIL graft copolymers were finally constructed in IL using guar macroRAFT agents. As PILs combine the attributes emanating from IL molecules (non-volatile, thermally stable, conducting…) with the ones of polymers in terms of mechanical reinforcement, the resulting polymers were exploited to elaborate high performance biohybrid materials. The cornerstone of this subsequent work was based on the straightforward formation of three-component blends: (i) poly(AEMIBr), (ii) guar and (ii) ionic liquid: butylmethylimidazolium chloride (BMIMCl). The pathway to obtain such ternary blends is very simple, since it only implies successive polymer solubilisation steps in IL. The rheological and thermal properties of the resulting materials were investigated. Also, the internal morphology by WAXS and SAXS measurements as well as the ionic transport were studied. It appeared that strong synergistic hydrogen bonding are developed between guar and PIL chains in addition to PIL/IL and guar/IL interactions. Ionogels with high elastic modulus (up to 30 000 Pa) and high thermal stability (up to 310°C) were prepared. Importantly, addition of PIL significantly enhanced the dimensional stability of the resulting ionogels and overcame IL exudation encountered in IL/guar binary systems. SAXS and WAXS revealed a homogeneous morphology and the ionogels were proven to exhibit excellent conductive properties (10-4 S/cm at 30°C) thanks to their highly continuous morphology. The resulting sustainable multicomponent materials may find applications as gel electrolyte for biobattery systems or supercapacitors.