京都大学 / 新制・課程博士 / 博士(工学) / 甲第23217号 / 工博第4861号 / 新制||工||1759(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 作花 哲夫, 教授 安部 武志, 教授 佐藤 啓文 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21123号 / 工博第4487号 / 新制||工||1697(附属図書館) / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 佐藤 啓文, 教授 関 修平, 教授 山本 量一 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

The flow properties of polydimethylsiloxane (PDMS) melts at room temperature were studied by measurement of lubrication forces using an Atomic Force Microscopy (AFM) colloidal force probe. A glass probe was driven toward a glass plate at piezo drive rates in the range of 12 – 120 μm/s, which produced shear rates up to ~10⁴ s⁻¹. The forces on the probe and the separation from the plate were measured. Two hypotheses were examined: (1) when a hydrophilic glass is immersed in a flow of polymer melt, does a thin layer of water form at the glass surface to lubricate the flow of polymer and (2) when a polymer melt is subject under a shear stress, do molecules within the melt spatially redistribute to form a lubrication layer of smaller molecules at the solid surface to enhance the flow? To examine the effect of a water lubrication layer, forces were compared in the presence and the absence of a thin water layer. The presence of the water layer was controlled by hydrophobization of the solid. In the second part, the possibility of forming a lubrication layer during shear was examined. Three polymer melts were compared: octamethyltrisiloxane (OMTS, n = 3), PDMS (n _avg = 322), and a mixture of 70 weight% PDMS and 30 weight% OMTS. We examined whether the spatial variation in the composition of the polymer melt would occur to relieve the shear stress. The prediction was that the trimer (OMTS) would become concentrated in the high shear stress region in the thin film, thereby decreasing the viscosity in that region, and mitigating the shear stress. / Master of Science

La plupart des modules photovolta¨ıques produits sont `a base de silicium.L’efficacit´e de ces modules d´epend fortement de la qualit´e cristalline du siliciumutilis´ee ainsi que de la quantit´e d’impuret´es pr´esente dans le lingotd’origine d’o`u sont issus les modules. Les lingots de silicium sont obtenus aucours d’un proc´ed´e de solidification, durant lequel les impuret´es sont extraitespar ph´enom`ene de s´egr´egation. Le processus de s´egr´egation est influenc´e parl’´ecoulement dans le liquide durant l’´etape de solidification. L’utilisation d’unchamp magn´etique externe permet le contrˆole de l’´ecoulement dans le bainliquide. Dans cette ´etude, l’effet d’un ´ecoulement forc´e sur le processus des´egr´egation est ´etudi´e. Pour cela un dispositif exp´erimental (VB2) et unmod`ele num´erique ont ´et´e d´evelopp´es dans le but de comprendre le rˆole del’´ecoulement sur la forme de l’interface et sur la s´egr´egation des impuret´es. / The photovoltaic modules are generally produced using silicon wafers. Theirelectrical efficiency is related to the crystal quality, which is influenced bythe presence of pollutants in the ingots from which the wafers are cut. Siliconingots are obtained as a result of solidification processes, which implygrowing a crystal from melt. During this solidification process, impurities areseparated from the silicon. The segregation process is greatly influenced bythe melt velocity during the solidification process. The control of the meltflow during the crystallization process can be achieved using external magneticfields. This thesis presents the results of the study on the influence ofthe forced convection induced by a travelling magnetic field (TMF) duringthe solidification process, using both an experimental set-up (VB2) and anumerical model.

Human practices have resulted in great damage to the environment. Carbon-depletion, water and air pollution, as well as global warming are examples of the environmental footprints caused by several industries and their related applications. Detergency (cleaning) is widely practiced operation in household, industry and institutional sectors and thus consumes significant amounts of water, energy and chemicals and, therefore, contributes appreciably to the environmental destruction. This process is still not fully understood, on a molecular level, and not acceptably optimised. Therefore, this study is a contribution toward a better fundamental understanding and optimisation of protein stain removal from interfaces, which may ultimately result in the development of environmentally friendly and sustainable cleaning products and technologies. In this research, the cleaning of rubisco, a grassy protein stain, from different surfaces (hydrophobic, hydrophilic, and dyed) using different cleaning agent formulations was investigated. These studies encompassed experimental work and fundamental analysis in terms of mathematical modelling. The results revealed a consistent correlation between enzyme adsorption kinetics and stain cleanability. Higher adsorption and desorption absolute rates ( a k and d k ) resulted in higher enzyme mobility and thus higher stain cleanability regardless of the enzyme adsorbed amount. Surface chemistry underlying the stain has indirectly influenced stain cleanability through the alteration of enzyme adsorption kinetics. Such fundamental findings may aid in screening enzyme candidates for detergent formulations and may also assist in designing easily cleanable surfaces. Another fundamental finding is the cooperative cleaning mechanism of surfactant and enzyme of rubisco stain from different interfaces. The break down of intermolecular physical bonds between interfacial rubisco molecules by surfactants and the break down of the intramolecular covalent bonds by enzyme resulted in a higher protein displacement from interfaces. The overall protein removal by the two different actions of surfactant and enzyme showed a superiority of a biosurfactant-enzyme formulation. This finding may have significant implications on developing sustainable detergents that have superior cleaning performance and no or minimal environmental hazard. Overall, the findings reported in this Ph.D. thesis may form a basis for further comprehensive scientific research, which may ultimately provide detergent market with more efficient and optimum cleaning products and technologies.

No description available.

<p>The structural and thermodynamic properties of a crystal-melt interface in</p> <p>elemental magnesium have been investigated using molecular dynamics (MD)</p> <p>simulations with an embedded atom method description of the interatomic potential.</p> <p>Three low index interfacial orientations, (0001), (1101) and (1120), have been studied.</p> <p>From fine-grained atomic density profiles, the structural interfacial widths show obvious anisotropy and the variation of interatomic planar spacing as a function of distance through the crystal-melt boundary is established. Mainly from the coarse-grained density profiles, the effective 10-90 width of the interface region, defined as the intrinsic width, in each orientation has been determined. In addition, the interfacial stresses are obtained from an integration of the interfacial stress profiles and the results show significant anisotropy, which is possibly related to the anisotropy of occupation fraction profiles. Finally, from a determination of the excess energy and interfacial stress of the solid-liquid interface and from previous published results for the interfacial free energy at the melting point, the Gibbs-Cahn integration is employed to derive an estimation of the temperature dependence of the interfacial free energy at non-equilibrium temperatures. All of the crystal-melt interfacial properties for magnesium are compared with simulation data from other elemental metals and alloys, as well as from other model systems such as Lennard- Jones and hard spheres.</p> / Master of Applied Science (MASc)

Ionic liquids (ILs) present new approaches for controlling interactions at the solid-liquid interface. ILs are defined as liquids consisting of bulky and asymmetric ions, with a melting point below 373 K. Owing to their amphiphilic character they are powerful solvents but also possess other interesting properties. For example, ILs can self-assemble and are attracted to surfaces due to their charged nature. As a result, they are capable of forming nanostructures both in bulk and at interfaces. This thesis describes how the solid-IL interface responds to external influences such as elevated temperatures, the addition of salt and polarisation. An improved understanding of how these factors govern the surface composition can provide tools for tuning systems to specific applications such as friction. Normal and friction forces are measured for ethylammonium nitrate (EAN) immersed between a mica surface and a silica probe, at different temperatures or salt concentrations. The results demonstrate that an increase in temperature or low concentrations of added salt only induce small changes in the interfacial structure and that the boundary layer properties remain intact. In contrast, at sufficiently large salt concentrations the smaller lithium ion prevails and the surface composition changes. The interfacial layer of a similar IL is also investigated upon the addition of salt and the results reveal that lithium ions affect the surface composition differently depending on the ion structure of the IL. This demonstrates that the surface selectivity strongly depends on the ion chemistry. Remarkably, a repulsive double layer force manifests itself for EAN at 393 K, which is not observed for lower temperatures. This indicates a temperature dependent change in EAN’s microscopic association behaviour and has general implications for how ILs are perceived. A new method is developed based on a quartz crystal microbalance to investigate how the surface compositions of ILs respond to polarisation. The approach demonstrates that interfacial layers of both a neat IL and an IL dissolved in oil can be controlled using potentials of different magnitudes and signs. Furthermore, the method enables two independent approaches for monitoring the charges during polarisation which can be used to quantify the surface composition. The technique also provides information on ion kinetics and surface selectivity. This work contributes to the fundamental understanding of the solid-IL interface and demonstrates that the surface composition of ILs can be controlled and monitored using different approaches. / Jonvätskor möjliggör nya tillvägagångssätt för att kontrollera interaktioner vid gränsskiktet mellan fasta ytor och vätskor. Jonvätskor definieras som vätskor som består av stora och asymmetriska joner med en smältpunkt under 373 K. På grund av sin amfifila karaktär är de starka lösningsmedel men har också andra intressanta egenskaper. Jonvätskor kan till exempel självorganisera sig och attraheras till ytor på grund av sin laddning. En följd av detta är att de bildar nanostrukturer både i bulk och på ytor. Denna avhandling beskriver hur gränsskiktet mellan fasta ytor och jonvätskor svarar på yttre påverkan såsom en ökning i temperatur, tillsättning av ett salt samt polarisering. En ökad förståelse för hur dessa faktorer styr ytkompositionen av jonvätskor kan bidra med verktyg för att kontrollera system till specifika applikationer såsom friktion. Normala- och friktionskrafter mäts för etylammonium nitrat (EAN) mellan en glimmeryta och en kolloidprob vid olika temperaturer eller saltkoncentrationer. Resultaten visar att en ökning av temperatur eller låga koncentrationer av tillsatt salt bara marginellt framkallar ändringar i strukturen på gränsytan och att det adsorberade lagret förblir intakt. När saltkoncentrationen emellertid var tillräckligt hög får den mindre litiumjonen överhanden och ytsammansättningen ändras. Ytlagret av en liknande jonvätska undersöks också vid tillsättning av salt och resultaten avslöjar att litiumjoner påverkar ytsammansättningen annorlunda beroende på jonstrukturen av jonvätskan. Detta visar att ytselektiviteten starkt beror på jonkemin. En repulsiv dubbellagerkraft yttrar sig anmärkningsvärt för EAN vid 393 K vilket inte observeras vid lägre temperaturer. Detta indikerar en ändring i EANs mikroskopiska sammansättningsbeteende och har generella återverkningar för hur jonvätskor uppfattas. En ny metod har utvecklats baserad på en kvartskristall mikrovåg för att undersöka hur ytsammansättningen av jonvätskor reagerar på polarisering. Denna metod visar att det adsorberade lagret av både en ren jonvätska och en jonvätska löst i olja kan kontrolleras genom att applicera spänningar med olika tecken och storlekar. Dessutom möjliggör metoden två oberoende tillvägagångssätt för att övervaka laddningarna under polarisering vilket kan användas för att kvantifiera ytsammansättningen. Tekniken ger också information om jonkinetik och ytselektivitet. Detta arbete bidrar till den grundläggande förståelsen av gränsskiktet mellan fasta ytor och jonvätskor och visar att ytsammansättningen av jonvätskor kan kontrolleras och övervakas med olika tillvägagångssätt. / <p>QC 20160518</p>

Le présent manuscrit présente le développement méthodologique du calcul de la tension de surface d’interfaces solide-liquide via des simulations de dynamique moléculaire. Après une courte présentation des avancées dans le domaine du calcul de la tension de surface pour les interfaces fluide-fluide et solide-fluide, les principales méthodes de calcul de la tension de surface d’un point de vue théorique sont montrées et généralisées pour le cas des interfaces solide-liquide, puis mises en oeuvre dans le cas de simulations de dynamique moléculaire. Un système école, constitué d’une feuille de graphène pour la phase solide et d’un bain de méthane pour la phase liquide, est ensuite étudié pour observer l’influence des artefacts de simulation sur le calcul de la tension de surface, montrant en particulier des effets de taille bien plus importants que pour le cas des interfaces liquide-liquide. Un autre système constitué d’une tranche de cuivre pour la phase solide, et d’un bain de méthane pour la phase liquide, a permis d’étudier l’effet inédit aux systèmes solide-liquide appelé anisotropie, montrant en particulier l’importance du caractère tensoriel de la tension de surface pour ce type de système. L’influence des paramètres du potentiel croisé entre les atomes de cuivre et de méthane est ensuite étudié. Finalement, deux systèmes applicatifs sont abordés, d’une part le système graphène-eau permettant d’étudier les effets de l’interaction électrostatique, et d’autre part un système constitué d’un solide explosif, le 1,3,5-triamino-2,4,6-trinitrobenzène (TATB) en contact avec un bain polymère pour la phase liquide, représentatif d’un cas réel d’intérêt. / This manuscript presents the methodological development of surface tension calculation of solid-liquidinterfaces via molecular dynamics simulations. After a short presentation of the advances in the field ofsurface tension calculation for fluid-fluid and solid-fluid interfaces, the main methods of surface tensioncalculation from a theoretical point of view are shown and generalized for solid-liquid interfaces, thenimplemented in the case of molecular dynamics simulations. A school system, consisting of a graphenesheet for the solid phase and a methane bath for the liquid phase, is then studied to observe the influenceof simulation artifacts on the surface tension calculation, showing in particular much larger size effectsthan in the case of liquid-liquid interfaces. Another system consisting of a copper slice for the solid phaseand a methane bath for the liquid phase made it possible to study the novel effect of solid-liquid systemscalled anisotropy, showing in particular the importance of the tensor character of the surface tension forthis type of system. The influence of the parameters of the cross potential between copper and methaneatoms is then studied. Finally, two application systems are discussed, on the one hand the graphene-watersystem for studying the effects of electrostatic interaction, and on the other hand a system consisting ofan explosive solid, 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) in contact with a polymer bath for theliquid phase, representing a real case of interest.

Les charges à l'interface liquide/solide sont un élément originel majeur des phénomènes électrocinétiques observés en micro/nanofluidique. Elles sont donc la colonne vertébrale de mon manuscrit de thèse, qui se décompose en trois parties : Dans la première partie, un rappel des concepts de base sur les interfaces liquides/solides est proposé au lecteur. Il est suivi d'une description des différentes méthodes expérimentales permettant de mesurer le potentiel zeta de couples solide/électrolyte, puis d'une présentation des travaux de la littérature exploitant les charges aux interfaces pour la préconcentration de molécules biologiques dans des systèmes Micro-Nano-Micro (MNM) fluidiques. Ensuite, une deuxième partie est consacrée à la mesure du potentiel zeta par la méthode des courants d'écoulement. Nous y présentons l'amélioration du banc expérimental issu des travaux antérieurs à ma thèse, ainsi que le développement de nouveaux protocoles de préparation des surfaces permettant de rationaliser et de stabiliser les mesures. Une application à un détecteur original de molécules biologiques clos cette deuxième partie. Enfin, la troisième et dernière partie s'intéresse à la préconcentration de molécules biologiques. Une méthode originale de fabrication des dispositifs MNM et les résultats de préconcentration obtenus, très encourageants, sont décrits. Des premiers modèles numériques et phénoménologiques sont proposés, qui mettent en avant l'originalité de notre travail / The charges at liquid/solid interfaces are a key element for both understanding and exploiting the electrokinetic phenomena in micro/nanofluidics. The manuscript of my Ph.D thesis is dedicated to these phenomena, which is divided into three main parts: Above all, a simple overview of charges at the liquid/solid interface is proposed. Then, several common methods for measuring the zeta potential at the liquid/solid interface are described. Next, various effective methods to preconcentrate the biological molecules is presented with the help of the surface charges. Secondly, the streaming current, which is a standard method to measure the zeta potential in our laboratory, is detailed. It contains the upgrade of the experimental setup from the previous version and the development of new protocols, which improve dramatically the stabilization and the reproducibility of the measurements. In addition, an original biological sensor is briefly presented based on these advancements. Lastly, in the final part, we describe a method which is primitively utilised in the fabrication of Micro-Nano-Micro fluidic system. Based on this system, some favorable preconcentration results is obtained. Moreover, numerical simulations are presented to prove the originality of our work