Le diamant de synthèse présente un intérêt croissant pour des applications diverses dans les domaines de l’optique, la catalyse, la biologie ou encore l’électronique. Par dépôt chimique en phase vapeur (CVD) ou par haute pression et haute température (HPHT), il peut être synthétisé sous forme de films. Les particules de diamant sont généralement produites par détonation ou par broyage de diamant massif. Cependant, il n’existe pas actuellement de particules de diamant combinant à la fois sphéricité, monodispersité et qualité cristalline contrôlée. Dans ce contexte, l’objectif de ce travail de thèse est d’élaborer un matériau diamant répondant à ces critères. Pour cela, des cœur-coquilles de diamant nanocristallin sphériques et monodisperses de taille micrométrique ont été synthétisés à partir de billes de silice ensemencées par des nanodiamants. Le revêtement de diamant nanocristallin a été obtenu dans un réacteur CVD spécifique dédié au traitement de poudres. En faisant varier la composition du mélange gazeux, la nature du revêtement a pu être modifiée, du diamant nanocristallin à un matériau hybride composé de nanodiamants enrobés d’une matrice graphitique. Des méthodes de caractérisations complémentaires comme la spectroscopie Raman et le HR-TEM ont permis de déterminer la structure cristalline de ces différents revêtements. Un traitement d’oxydation des cœur-coquilles a permis de les disperser en suspension colloïdale dans l’eau. En utilisant un traitement basique, des sphères creuses ont pu être obtenues et mises en suspension. Des études préliminaires des performances de ces différents matériaux ont ensuite été menées : les propriétés photo-électrocatalytiques pour la réduction du CO2 et la cytotoxicité in vitro pour des applications en biologie. La méthode d’élaboration des cœur-coquilles de diamant mise au point a été enfin étendue à des cœurs magnétiques de maghémite. / Synthetic diamond is now considered in various fields of applications like optics, catalysis, biology or even electronic. Thin films can be synthesized by Chemical Vapor Deposition (CVD) or by High Pressure/ High Temperature (HPHT), while particles are produced by detonation synthesis or milling of bulk diamond. Nevertheless, among all these diamond materials, there is no material available combining sphericity, monodispersity and crystalline quality. This is the purpose of this thesis work. Core-shell systems made of nanocrystalline diamond shell surrounding a silica core have been synthesized, starting from nanodiamond-seeded silica particles. These particles have been grown in a dedicated home-made CVD reactor, specifically developed to treat powders. Varying the gas composition, the nature of the coating has been tuned, from nanocrystalline diamond to a hybrid material made of nanodiamond particles surrounded by organized graphite. Complementary techniques such as Raman spectroscopy and High Resolution Transmission Electronic Microscopy (HR-TEM) have been used to characterize the crystalline structures. Colloidal suspensions were also obtained with these new diamond core-shells, by oxidation of their surface. Dissolving the silica core, diamond shells were also synthesized, exhibiting stable colloidal properties. Preliminary studies on diamond core-shells performances are also presented in this manuscript: their photocatalytic properties toward CO2 reduction and their in-vitro cytotoxicity considering further biological applications. Finally, the manuscript also reports on the extension of the process to magnetic silica cores for the synthesis of magnetic diamond core-shells.

Preparative mass spectrometry is an important method for the synthesis of new materials. Recently, soft landing mass spectrometry has been used to land ions on surfaces to coat or otherwise alter them. Commercial soft landing instruments do not yet exist, and the physical phenomenon of soft landing has not yet been fully described. For future ion mobility soft landing research, the theory of ion mobility, ion optics and soft landing is discussed, and 2 soft landing instruments have been built and described, along with proof of concept experiments for both instruments. Simulations of the process of ion mobility and ion optics for use in these instruments, as well as some preliminary results for the optics are included. Surfaces described include copper on mica and iron on silicon. Self assembly of soft landed ions is observed on the surfaces. The instruments constructed will be useful for future soft landing research, and soft landing can be used for future materials research with special attention focused on the self-assembly of the landed ions.

Membrane fouling, which is caused by deposition/adsorption of foulants on the surface or within membrane pores, still remains a bottleneck that hampers the widespread application of membrane bioreactor (MBR) technology for wastewater treatment. Recently membrane surface modification has proved to be a useful method in water/wastewater treatment to improve the surface hydrophilicity of membranes to obtain higher water fluxes and to reduce fouling. In this study, membrane modification was investigated by depositing a thin film of same thickness of TiO2 on the surface of an ultrafiltration alumina membrane. Various thin-film deposition (TFD) methods were employed, i.e. electron-beam evaporation, sputter and atomic layer deposition (ALD), and a comparative study of the methods was conducted to assess fouling inhibition performance in a lab-scale anaerobic MBR (AnMBR) fed with synthetic municipal wastewater. Thorough surface characterization of all modified membranes was carried out along with clean water permeability (CWP) tests and fouling behavior by bovine serum albumin (BSA) adsorption tests. The study showed better fouling inhibition performance of all modified membranes; however the effect varied due to different surface characteristics obtained by different deposition methods. As a result, ALD-modified membrane showed a superior status in terms of surface characteristics and fouling inhibition performance in AnMBR filtration tests. Hence ALD was determined to be the best TFD method for alumina membrane surface modification for this study. ALD-modified membranes were further characterized to determine an optimum thickness of TiO2-film by applying different ALD cycles. ALD treatment significantly improved the surface hydrophilicity of the unmodified membrane. Also ALD-TiO2 modification was observed to reduce the surface roughness of original alumina membrane, which in turn enhanced the anti-fouling properties of modified membranes. Finally, a same thickness of ALD-TiO2 and ALD-SnO2 modified membranes were tested for alginate fouling inhibition performance in a dead-end constant-pressure filtration system. This is the first report on the application of SnO2-modified ceramic membrane for testing its alginate fouling potential; which was determined to be nearly-same for both modified membranes with a negligible amount of difference. This revealed SnO2 as a potential future anti-foulant to be tested for membrane modification/fabrication for application in water/wastewater treatment systems.

abstract: Chemical modification of (semi)conducting surfaces with soft-material coatings containing electrocatalysts provides a strategy for developing integrated constructs that capture, convert, and store solar energy as fuels. However, a lack of effective strategies for interfacing electrocatalysts with solid-state materials, and an incomplete understanding of performance limiting factors, inhibit further development. In this work, chemical modification of a nanostructured transparent conductive oxide, and the III-V semiconductor, gallium phosphide, is achieved by applying a thin-film polymer coating containing appropriate functional groups to direct, template, and assemble molecular cobalt catalysts for activating fuel-forming reactions. The heterogeneous-homogeneous conducting assemblies enable comparisons of the structural and electrochemical properties of these materials with their homogeneous electrocatalytic counterparts. For these hybrid constructs, rational design of the local soft-material environment yields a nearly one-volt span in the redox chemistry of the cobalt metal centers. Further, assessment of the interplay between light absorption, charge transfer, and catalytic activity in studies involving molecular-catalyst-modified semiconductors affords models to describe the rates of photoelectrosynthetic fuel production as a function of the steady-state concentration of catalysts present in their activated form. These models provide a conceptual framework for extracting kinetic and thermodynamic benchmarking parameters. Finally, investigation of molecular ‘proton wires’ inspired by the Tyrosine Z-Histidine 190 redox pair in Photosystem II, provides insight into fundamental principles governing proton-coupled electron transfer, a process essential to all fuel-forming reactions relevant to solar fuel generation. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2020

京都大学 / 0048 / 新制・課程博士 / 博士(人間・環境学) / 甲第22550号 / 人博第953号 / 新制||人||226(附属図書館) / 2019||人博||953(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 吉田 寿雄, 教授 内本 喜晴, 教授 田部 勢津久 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DFAM

<div>Plasma treatment of polymers has been a rapidly growing area of research due to its broad applications, homogenous and repeatable surface properties, low cost, and environmental friendliness when compared to alternative techniques. Only recently have significant developments been made in the application of atmospheric pressure plasma in polymer surface treatment. The use of atmospheric pressure plasma enables further reductions in cost and mechanical complexity. Of particular interest in this work is the application of atmospheric pressure plasma for the isolated modification of the inner surfaces of small diameter polymer tubing to improve the wetting and adhesion characteristics compared to untreated polymer.</div><div>This work focuses on the development, characterization, and implementation of an atmospheric pressure dielectric barrier discharge (DBD) plasma apparatus for the treatment of the inner surface of polymer tubes. The iterative process of the development of this system is detailed, with two finalized designs established and defined. These two designs are then applied to low density polyethylene (LDPE) tubing of 0.38 mm inner diameter (ID), and characteristics for surface morphology and wettability are analyzed.</div><div>Investigation of the relationship between plasma power and treatment time with morphology characteristics of protrusion density and size and surface roughness parameter, R_a is presented. Treatment times of 5, 10, 15, 30 and 45 minutes are performed on tubing samples at a power level of 35 mW. From 5 to 15 minutes, protusion density increases rapidly, from n_p=4*10^4- 10^7 protrusions/(mm^2 ), and small variation in protrusion size, with 0.1< A_p<0.2 μm^2. At treatment times of 30 and 45 minutes, coalescence of protrusions was observed, resulting in a decrease in protrusion density, down to n≈4*10^4 protrusions/(mm^2 ), and substantial increases in mean protrusion size, up to A_P=5-9 μm^2. Plasma powers of 9, 12, 16, 25, 35, and 45 mW were also investigated, at a treatment time of 15 minutes. As power level was increased, protrusion density was observed to increase, with an inverse relationship with mean protrusion size. Protrusion density was observed to increase from n_p=2*10^5-10^7 protrusions/(mm^2 ), with diminishing increases in density observed between power levels of 35 and 45 mW. Protrusion mean size was observed to decrease from A_p= .25-0.025 μm^2, with similar diminishing reductions observed at 35 and 45 mW. Surface roughness, R_a, was observed to vary from .01-0.3 μm, or ISO roughness grades N1 to N5, in the treated samples.</div><div>Wettability characteristics were measured and characterized relative to plasma power and linear feed rate. Wettability was measured by measurement of contact angles of the meniscus formed from water introduced into the tubing volume by capillary action. On all samples treated, a duality of mechanisms for surface wetting were observed. After initial treatment, samples were observed to have a lower contact angle, indicating higher wettability, but after 12 hours samples were observed to have reduced wetting characteristics, indicating a transient mechanism for surface wetting in addition to permanent effects induced my surface morphology. Samples were treated at plasma powers of 7, 10, 15, 20, and 40 mW. At all power levels, initial contact angle was generally consistent, with 20^o< θ_0<30^o. Permanent wetting features measured on these samples indicated almost complete reversing of wettability at 7 and 10 mW, with θ_SS measured at ~75^o, comparable to the average measurement of an untreated sample of ~80^o. Conversely, at higher powers of 15, 20 and 40 mW, significant retention of wettability was observed, with 45^o<θ_SS<55^o for those samples.</div><div><br></div>

The goal of diploma thesis is study of the effect of thermal annealing at different temperatures and different annealing durations on the surface structure of oxide ceramics based on Al2O3 and study of the samples porosity.

Cellulose nanocomposites offer interesting potential in terms of improved properties and new functionalities compared with microcomposites. Preparation from colloidal suspensions is promising, since high reinforcement content is possible and a wide range of constituents can be used. In the first study, the challenge is to form a stable suspension of well-dispersed carbon nanotubes (CNT) and nanofibrillated cellulose (NFC) in water and to prepare commingled high CNT content nanopaper structures by filtration. Various surfactants were used to modify CNT. The NFC was stabilized by charged carboxylate groups. A nonylphenol phosphate ester surfactant, NPPE, worked well for CNT and provided a stable and well-dispersed water suspension of CNT and NFC. Field emission scanning electron microscopy (FE-SEM), porosimetry and atomic force microscopy (AFM) were used to characterize nanopaper structure, and tensile properties were measured as well as surface resistivity. The processing route is water based and it is possible to prepare thin coatings as well as thicker films with a combination of low surface resistivity, flexibility in bending and high strength and toughness in tension.  As inspired by organo-modified layered silicates, the objective of the second study is to develop an environmentally friendly procedure for the surface modification of cellulose nanocrystals, CNC, using quaternary ammonium salts via adsorption. In order to obtain higher surface charge density on CNC, a new route is developed for preparation of CNC with carboxylic acid groups. Quanternary ammonium cations bearing alkyl, phenyl, glycidyl, and diallyl groups are used to modify CNC to render their surface more hydrophobic. The structure and surface hydrophobicity of unmodified and modified CNC as well as their dispersibility in organic solvent are characterized by AFM, FE-SEM, Fourier-transformed infrared spectroscopy (FT-IR), X-Ray analysis (XDR) and contact angle measurement (CAM). Future work will focus on surface-modified nanocelluloses in composite materials, in order to learn more about surface treatment effects on nanocomposite properties. / Nanokompositer från cellulosa har potential att ge starkt förbättrade egenskaper och ny funktionalitet jämfört med mikrokompositer. De ger även möjlighet till komposittillverkning från kolloidala suspensioner där man kan uppnå hög halt av förstärkningsfasen. Det är också möjligt att välja från en bred flora av lösliga och dispergerbara materialkomponenter. I första studien är utmaningen att skapa en stabil och väldispergerad suspension av kolnanorör (CNT) och nanofibrillerad cellulosa (NFC) i vatten för att genom filtrering framställa nanopapper med interpenetrerande CNT och NFC nätverk. Olika ytaktiva ämnen användes för att modifiera CNT. NFC stabiliserades genom laddade karboxylgrupper på ytan. En nonylfenol fosfatester, NPPE, fungerade bra för CNT och resulterade i en stabil och väldispergerad vattensuspension av CNT och NFC. FE-SEM, densitometri och AFM användes för att karakterisera nanopapperstruktur. Mekaniska egenskaper och ytresistivitet mättes. Processen för framställning av CNT/NFC nanopapper är vattenbaserade och det är möjligt att framställa tunna ytbeläggningar likväl som tjockare filmer. Dessa strukturer har en kombination av låg resistivitet, flexibilitet i böjning liksom hög hållfasthet och seghet i dragbelastning.  Syftet med den andra studien är att utgå från organo-modifierade skiktade silikater (leror) för att utveckla en miljövänlig ytmodifieringsmetod för nanocellulosa. För att öka ytladdningstätheten på CNC (nanokristaller från cellulosa) utvecklas ett nytt sätt att skapa karboxylgrupper på ytan. Kvarternära ammoniumsalter med alkyl, fenyl, glycidyl och diallylgrupper används för att göra ytan på CNC mer hydrofob. Ytans struktur och hydrofoba karaktär, liksom dispersionsegenskaper i organiska lösningsmedel, karakteriseras med hjälp av AFM, FE-SEM, FT-IR, XDR och kontaktvinkelmätning. Fortsatt arbete kommer att fokusera på ytmodifierad cellulosa i kompositmaterial, för att utveckla förståelsen för effekter av ytmodifiering på nanokompositers egenskaper / <p>QC 20120302</p>

In this study, a magnetic nanomaterial was used for the binding of anionic arsenic species from contaminated groundwater. Iron oxide (Fe3O4) magnetic nanoparticles (NPs) and the surface modified Fe3O4 NPs with 3-aminopropyl-triethoxysilane (3-APTES), Trisodium citrare (TSC) and Chitosan were synthesized with the co-precipitation method. Structural characterizations showed that the four kinds of NPs had different sizes an average particle range size of 15-20 nm was observed with Transmission Electron Microscopy. X-ray diffraction was used to identify the crystalline structure of synthesized Fe3O4 and surface modified NPs. Molecular structure and functional groups present in synthesized magnetic NPs Fe3O4 were identify with infrared analysis. The synthesized Fe3O4 NPs and surface coated NPs were used for determine the binding capacity of Arsenic ions from the synthetic groundwater. The binding of As(III) increased as the dissolved As(III) concentration increased in the solution. From the experiments it was found chitosan-coated NPs are best than other coated and uncoated NPs for arsenite removal from the solution. It was found that if only As(III) ions were present in the water without other anions and cations the binding capacity of the magnetic NPs is very high. The binding capacity of As ions was decreased with presence of other anions and cations in the groundwater because they interfere with arsenic binding sites which presence on the magnetic NPs.

Plant cuticles are extracellular membranes covering aerial organs of plants, whose main functions rely on the protection against water loss, mechanical injury from the environment, attack of microorganism, and also regulation of gas exchange. Among the several constituents of plant cuticles, waxes are those that play an important role in their barrier properties. In order to enhance the mechanical properties of wax, NFC was applied in. In the project, mainly two kinds of methods were used to prepare wax-NFC composites. One way was wax and NFC were dissolved in toluene and casted to be a film, another way was to prepare NFC aerogel firstly, and then, impregnated the aerogel into wax liquid. After pressing it the structure was more compact. In order to characterize the properties of samples, SEM, XRD, TGA, DSC, Contact angle testing, tensile test and oxygen permeability methods were applied in.