An ancient technology of solar-driven water evaporation and distillation has recently been revived due to the concept of interfacial solar evaporation and the development of photothermal materials. There have been many research interests in improving solar light harvesting and solar-to-water evaporation efficiency within these systems, including new photothermal materials search, structural engineering, and thermal management. The application horizon of both solar-driven water evaporation and distillation has been broadly expanded beyond their conventional domain, including now wastewater treatment, seawater desalination, steam sterilization, electric generation, and chemicals/fuels productions. This dissertation focused on designing of photothermal materials and their applications to clean water production. More specifically: (1) a bi-layered porous rGO membrane with a polystyrene (PS) foam as the heat insulator was designed and proved to be effective for reducing heat conduction to the bulk water and to improve the solar-to-water evaporation efficiency, (2) a tandem-structured SiC-C ceramic monolith was prepared and demonstrated to be mechanically and chemically stable to withstand physical or chemical cleaning during long-term use in real seawater and wastewater, (3) in order to simultaneously treat the contaminated water and get clean distillate water, multi-functional SiC foam modified with mesoporous Au/TiO2 nanocomposites has been prepared, which was demonstrated to possess both photocatalytic reduction and oxidation abilities for complex wastewater treatment, and (4) when the water source was contaminated by VOCs, another efficient multi-functional photothermal material was designed with a honeycomb ceramic plate as the matrix material, and a CuFeMnO4 nanocomposite coating layer acting as both photothermal material and Fenton agent for VOCs removal. Therefore, the light absorption property of photothermal material could be improved by using a porous structure, tandem-structure, porous foam or 3D structure. The solar-to-water evaporation efficiency was improved by including a heat insulator and the reduction of the water channels’ dimension. The ceramic-based material showed potential for long-term use with high mechanical strength to endure physical cleaning. Multi-functional photothermal materials were successfully developed for complex wastewater treatment and clean water generation.

Le groupe Mäder s’est lancé depuis quelques années dans une nouvelle thématique, la polymérisation « dual-cure ». Il s’agit d’un processus photo-thermique couplant réactivité photochimique et thermique. Cette thématique vise des applications pour lesquelles le produit est épais et/ou fortement chargé. La photopolymérisation étant limitée en profondeur, le processus thermique permet de compléter la polymérisation au coeur de l’échantillon ou encore dans les zones non accessibles par la technologie UV/LED. Cette thématique a fait l’œuvre d’une première thèse (2007-2010) menée par le doctorant Adrien Criqui au sein du Département de Photochimie Général (DPG). Au cours de cette thèse, la polymérisation radicalaire photo-thermique à partir d’aldéhydes a été étudiée. Des résultats concluant ont été obtenus donnant naissance à une technologie innovante notamment avec des applications sous air. Dès lors, il s’est posé la question de savoir si les aldéhydes pouvaient être utilisés dans la polymérisation cationique photo-thermique. La première année de thèse a donc commencé par l’étude du potentiel des aldéhydes dans la polymérisation cationique photo-thermique de résine époxydes. Les aldéhydes ont montrés qu’ils sont de bons photosensibilisateurs de la photopolymérisation cationique amorcée par un sel d’iodonium. Certaines structures aldéhydes couplées à un sel d’iodonium ont conduit à une polymérisation thermique. Les vitesses de polymérisation sont néanmoins trop lentes pour pouvoir être exploitées. La voie des aldéhydes a donc été abandonnée suite à ces résultats. Malgré ceci, ce sujet a fait l’œuvre d’une étude mécanistique qui a permit de conclure que le couple sel d’iodonium/aldéhyde réagit selon un mécanisme redox au courant duquel l’auto-oxydation de l’aldéhyde est indispensable. La réduction du photoamorceur par le radical issu de l’auto-oxydation de l’aldéhyde permet d’amorcer la polymérisation cationique. Par la suite, une importante bibliographie sur la polymérisation cationique des époxydes a été réalisée, le but étant de rechercher de nouveaux systèmes amorceurs. Plusieurs systèmes ont alors été retenus à savoir, les acides de Lewis et de Brönsted ainsi que les espèces cationiques. Les acides de Lewis étudiés n’ont pas apportés de résultats satisfaisants et ont donc été abandonnés. Parmi les acides de Brönsted, les acides sulfoniques ont été sélectionné. Des résultats mitigés ont été obtenus. En effet, soit la polymérisation s’est montrée trop rapide et non contrôlable soit trop lente. Le mécanisme de polymérisation amorcé par ces espèces ne semble pas adapté aux résines époxydes. La synthèse d’une structure appropriée a été envisagée mais pour des raisons stratégiques a été par la suite abandonnée. Plusieurs structures d’espèces cationiques ont été étudiées, à la fois des espèces commerciales (ex : triphénylcarbénium, …) ainsi que des espèces synthétisées au laboratoire (ex : xanthénium, …). Les travaux effectués sur ces systèmes amorceurs ont montrés qu’un amorçage indirect avec formation de l’amorceur in situ était une voie à privilégier.A partir de ce constat, deux technologies ont été étudiées. La première, à caractère purement académique, concerne une voie redox. Un système déjà publié basé sur le système sel d’iodonium/sel de cuivre/acétoïne a été ré-évalué. Les résultats obtenus ne correspondant pas au mécanisme publié, une étude mécanistique a été réalisée afin de proposer un nouveau mécanisme réactionnel. Le mécanisme de réaction est basé sur une réaction de décomposition, probablement par complexation, du sel d’iodonium par un sel de cuivre. Le produit de décomposition formé étant sensible à l’hydrolyse, il est possible d’accélérer la vitesse de polymérisation par la présence d’un composé hydroxylé type acétoïne. [...] / In the past few years, The Mäder Group has launched a new theme, " dual- cure " polymerization and process. This process is a coupling between photochemical and thermal reactivity. This theme is designed for applications where the product is thick and/or loaded with fillers. The photopolymerization is limited in depth and then the thermal process is used to complete the polymerization of the sample or in the non-irradiated areas. This theme has been the work of a first PhD (2007-2010) conducted by the student Adrien Criqui in the “Département de Photochimie Générale (DPG)”. In this PhD, the photo- and thermal radical polymerization with aldehydes was studied. Results have given birth to an innovative technology, particularly with applications under air. Therefore, it wonder if aldehydes could be used in the photo- and thermal cationic polymerization.The first year of PhD has begun with the study of the potential of aldehydes in the photo- and thermal cationic polymerization of epoxy resin. Aldehydes have shown that they are good photosensitizers of the cationic photopolymerization initiated by an iodonium salt. Some aldehydes coupled with an iodonium salt led to thermal polymerization. However rates of polymerization are too slow to be exploited. The way of aldehydes has been aborted due to these results. Despite this, this topic has been the work of a mechanistic study that led to the conclusion that the iodonium/aldehyde salt couple reacts according to a redox mechanism in which the auto-oxidation of the aldehyde is essential. The reduction of the photoinitiator by the radical derived from the auto- oxidation of the aldehyde aollow to initiate cationic polymerization.Subsequently, an extensive bibliography on the cationic polymerization of epoxides was carried out with the aim to find new initiator systems. Therefore, several systems have been selected i.e., Lewis and Brösted acids, and cationic species. Lewis acids studied gave no satisfactory results and were therefore given up. Among the Bronsted acids, sulfonic acids were selected. Mixed results were obtained. Sometimes the polymerization has been too fast and sometimes too slow. The polymerization mechanism initiated by these species does not seem suitable for epoxy resins. The synthesis of a suitable sulfonic acid was considered but for strategic reasons was later dropped. Several structures of cationic species have been also studied, both commercial species (eg: triphenylcarbenium , ... ) as well as synthesized species (eg: xanthénium ...). Work on these initiator systems convinced to use an indirect method to initiate polymerization.From this, two technologies have been studied. The first, relates to a redox pathway. A published system based on iodonium salt/copper salt/acetoïne combination has been re-evaluated. Results do not match the published mechanism. A new mechanistic has been proposed. The reaction mechanism is based on a decomposition reaction, presumably by complexation, of the iodonium salt with a copper salt. The decomposition product formed is susceptible to hydrolysis. Rates of polymerization have been accelerated the by the presence of a hydroxy compound like acetoïne. From the knowledges, ways of controlling the rate of polymerization (eg: complexing metal salt) and a new initiator system have been proposed. The second technology relates to a bi-component consisting of a photoinitiator/thermal initiator and a co- initiator. The reaction between the initiator and co-initiator allows initiating the polymerization. The polymerization rate can be controlled from the structure of initiator and co-initiator. The initiator is also a photoinitiator, the photo- and thermal nature is ensured. Two classes of co-initiators have been studied from a fundamental point of view (hydroperoxides and vinyl ether). It has been shown that hydroperoxides reduce initiator by an electron transfer. [...]

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Photothermal Radiometry is a common thermal property measurement technique which is used to measure the properties of layered materials. Photothermal Radiometry uses a modulated laser to heat a sample, in which the thermal response can be used to determine the thermal properties of layers in the sample. The motivation for this work is to provide a better understanding of the accuracy and the repeatability of the Photothermal Radiometry measurement technique. Through this work the sensitivity of results to input uncertainties will be determined. Additionally, using numerical simulations the overall uncertainty on a theoretical measurement will be determined. The repeatability of Photothermal Radiometry measurements is tested with the use of a proton irradiated zirconium carbide sample. Due to the proton irradiation this sample contains two layers with a thermal resistance between the layers. This sample has been independently measured by three different researchers, in three different countries and the results are compared to determine the repeatability of Photothermal Radiometry measurements. Finally, from sensitivity and uncertainty analysis experimental procedures and suggestions are provided to reduce the uncertainty in experimentally measured results.

京都大学 / 0048 / 新制・課程博士 / 博士(薬科学) / 甲第19668号 / 薬科博第56号 / 新制||薬科||7(附属図書館) / 32704 / 京都大学大学院薬学研究科薬科学専攻 / (主査)教授 髙倉 喜信, 教授 橋田 充, 教授 佐治 英郎 / 学位規則第4条第1項該当 / Doctor of Pharmaceutical Sciences / Kyoto University / DFAM

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Biological nanoparticles have enormous utility as well as potential adverse impacts in biotechnology, human health, and medicine. The physical and chemical properties of these nanoparticles have strong implications on their distribution, circulation, and clearance in vivo. Accurate morphological visualization and chemical characterization of nanoparticles by label-free (direct) optical microscopy would provide valuable insights into their natural and intrinsic properties. However, three major challenges related to label-free nanoparticle imaging must be overcome: (i) weak contrast due to exceptionally small size and low-refractive-index difference with the surrounding medium, (ii) inadequate spatial resolution to discern nanoscale features, and (iii) lack of chemical specificity. Advances in common-path interferometric microscopy have successfully overcome the weak contrast limitation and enabled direct detection of low-index biological nanoparticles down to single proteins. However, interferometric light microscopy does not overcome the diffraction limit, and studying the nanoparticle morphology at sub-wavelength spatial resolution remains a significant challenge. Moreover, chemical signature and composition are inaccessible in these interferometric optical measurements. This dissertation explores innovations in common-path interferometric microscopy to provide enhanced spatial resolution and chemical specificity in high-throughput imaging of individual nanoparticles. The dissertation research effort focuses on a particular modality of interferometric imaging, termed “single-particle interferometric reflectance (SPIR) microscopy”, that uses an oxide-coated silicon substrate for enhanced coherent detection of the weakly scattered light. We seek to advance three specific aspects of SPIR microscopy: sensitivity, spatial resolution, and chemical specificity. The first one is to enhance particle visibility via novel optical and computational methods that push optical detection sensitivity. The second one is to improve the lateral resolution beyond the system's classical limit by a new computational imaging method with an engineered illumination function that accesses high-resolution spatial information at the nanoscale. The last one is to extract a distinctive chemical signature by probing the mid-infrared absorption-induced photothermal effect. To realize these goals, we introduce new theoretical models and experimental concepts. This dissertation makes the following four major contributions in the wide-field common-path interferometric microscopy field: (1) formulating vectorial-optics based linear forward model that describes interferometric light scattering near planar interfaces in the quasi-static limit, (2) developing computationally efficient image reconstruction methods from defocus images to detect a single 25 nm dielectric nanoparticle, (3) developing asymmetric illumination based computational microscopy methods to achieve direct morphological visualization of nanoparticles at 150 nm, and (4) developing bond-selective interferometric microscopy to enable multispectral chemical imaging of sub-wavelength nanoparticles in the vibrational fingerprint region. Collectively, through these research projects, we demonstrate significant advancement in the wide-field common-path interferometric microscopy field to achieve high-resolution and accurate visualization and chemical characterization of a broad size range of individual biological nanoparticles with high sensitivity.

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Mid-infrared spectroscopic imaging, which leverages the inherent vibrational contrast of chemical bonds, has been a powerful analytical tool for sample characterization. However, its use in studying living systems is limited by low spatial resolution and significant water absorption. Recently developed mid-infrared photothermal (MIP) microscopy addresses these limitations by probing the absorption-induced photothermal effect using visible light. MIP microscopy achieves sub-micrometer spatial resolution and reduces water background interference. Yet, the imaging speed of current MIP microscopy is constrained by the challenge of measuring a small modulation over the probe laser background. This low imaging throughput hinders the visualization of living dynamics, and the rich molecular information in the spectroscopic domain is obscured due to the slow acquisition process. This dissertation explores solutions for enhancing imaging speed and spectral throughput and extending MIP imaging into visualizing chemical dynamics in living systems. In the first part of the dissertation, the mid-infrared photothermal process is studied and modeled in the time, frequency, and spatial domains using heat transfer analysis. Photothermal dynamics imaging (PDI) is introduced with the ability to visualize nanosecond-scale thermodynamics in samples upon laser excitation. By capturing all higher-order harmonics, PDI achieves more than a four-fold improvement in signal-to-noise ratio compared to the lock-in method for detecting low-duty cycle photothermal signals. An imaging speed nearly two orders of magnitude faster than the lock-in counterpart has been reached. In addition, PDI captures the transient thermal field evolution, providing a tool to gauge the target’s physical properties and microenvironment. In the second part, a video-rate MIP microscope is introduced based on the PDI detection method. In the system, a synchronized IR and visible beam scanning scheme is developed, enabling photothermal detection with a single IR pulse at each pixel. Moreover, synchronized laser scanning allows uniform MIP imaging in a field of view over hundreds of micrometers while maintaining a high spatial resolution. This capability enabled the visualization of fast chemical dynamics inside living fungal cells, cancer cells, and living worms, providing an imaging platform for biology research. Having reached the speed limitation of single-pulse imaging, we further advanced the speed of spectroscopic imaging by moving beyond the conventional measurement of absorption contrast in the photothermal process. In the final part of this dissertation, we revisited the photothermal process from the perspective of energy deposition, discovering that the absorption coefficient is reflected in the slope of the heating process rather than its overall amplitude. We demonstrated mid-infrared energy deposition (MIRED) spectroscopy using a 32-channel quantum cascade laser array that emits a broadband pulse train in microseconds. With MIRED, we achieved hyperspectral mid-infrared imaging on a microsecond scale.