Dissertations / Theses on the topic 'Microwave-heating assisted solvothermal synthesis'

Les nanomatériaux sont de plus en plus utilisés dans de nombreusesapplications, que cela soit pour la catalyse, la coloration, l’optique, etc. Pour optimiser leurutilisation, il est nécessaire de mieux comprendre les réactions et interactions ayant lieu à ceséchelles. Cette thèse se propose d’essayer d’explorer les liens entre conditions de synthèse,morphologie de particules, et propriétés de celles-ci. En particulier, nous avons opté pourl’étude d’un matériau modèle : l’oxyde de cérium (IV). Les nanoparticules de CeO2 ont étéobtenues par voie de synthèse solvothermale assistée par chauffage micro-ondes. Lesmorphologies des nanoparticules de CeO2 étudiées ont été : les cubes, les octaèdres et lesbâtonnets, et nous avons essayé de fournir une explication à leur obtention par la voie desynthèse utilisée. De l’or a ensuite été déposé en surface des ces nanoparticules de CeO2 etétudié par une combinaison d’études par Microscopie Électronique en Transmission et demodélisations numériques
Nanomaterials are more and more used in various situations, such as catalysis,color, optics, etc. To optimize their use, it is necessary to better understand reactions andinteractions taking place at these scales. This PhD thesis aims at exploring the links betweensynthesis conditions, particle morphology and their properties. In particular, we chose a tostudy a model-material: cerium (IV) oxide. CeO2 nanoparticles have been obtained bymicrowave-heating assisted solvothermal synthesis. Morphologies obtained and studied havebeen: cubes, octahedrons and rods. We tried to to give an explanation on how these synthesesallowed the formation of such morphologies. Gold has then be deposed on the surface of theseCeO2 nanoparticles, and studied by a combination of Transmission Electron Microscopystudies, and computer modelizations

Interest in rare-earth-doped crystalline materials, e.g., M(RE)F4 (M – alkali metal, RE – rare-earth metal), featuring unique optical properties such as light upconversion and downshifting is experiencing a surge due to the broad spectrum of applications that these photonic systems are facilitating. The development of reliable synthetic methods that grant rapid access to these materials is therefore of great importance. Microwave-assisted synthesis is appealing in this regard, because microwave radiation enables rapid and uniform heating of the reaction mixture and allows for rigid control of the reaction conditions, factors that facilitate the production of high-quality materials within minutes. Surprisingly, the investigation around microwave-assisted synthesis of M(RE)F4 materials featuring upconversion and downshifting luminescence is limited. Methods that have already been developed predominately target Na-based systems, despite the evidence that the Li-based analogues also display excellent optical properties. In fact, only a single microwave-assisted approach toward a nanoscale Li-based system has been reported to date, while to my knowledge, no report of a microwave-assisted synthesis of a microscale Li-based system existed prior to the commencement of the work presented in this thesis. The challenge lies in the fact that access to Li(RE)F4 is not easily achieved through a simple substitution of the alkali metal source in the established protocols that yield Na(RE)F4; rather, a complete re-optimization of the synthesis method is required. This particular challenge was successfully addressed in this work. Presented and discussed in Chapter 3 of this thesis is a rapid microwave-assisted solvothermal synthesis approach toward both upconverting and downshifting LiYF4:RE3+ microparticle systems. More specifically, it is detailed how the rigorous optimization of the reaction temperature/duration profile, initial reaction mixture pH, and ratio of the metal precursors was necessary in gaining control over the crystalline phase, morphology, and size of the microparticles under microwave-induced solvothermal conditions. Importantly, a materials growth mechanism involving the depletion of a Li-free crystal phase, followed by a particle ripening process is also proposed. Moreover, the versatility of the developed method is highlighted by showcasing how it can be extended toward the synthesis of other relevant Li- and Na-based M(RE)F4 nano- and microscale materials (i.e., LiYbF4, NaYF4, and NaGdF4) featuring upconversion luminescence. Lastly, potential challenges associated with microwave-assisted synthesis are discussed, and appropriate solutions are proposed. The upconversion and downshifting luminescence of the M(RE)F4 materials attained via the developed synthesis approach is investigated in Chapter 4. The first part of the chapter provides a general assessment of the characteristic luminescence generated by the M(RE)F4 materials featuring various RE3+ dopant systems. The second part of the chapter is devoted to a much more thorough single-particle investigation of the anisotropic luminescence behaviour exhibited by the LiYF4:RE3+ microparticles via hyperspectral imaging, polarized emission spectroscopy, and optical trapping. It is my hope that you, the reader, will find the work presented in this thesis stimulating from two vantage points – from the development of the most rapid microwave-assisted solvothermal synthesis of upconverting and downshifting M(RE)F4 nano/microscale materials reported to date, as well as from the utilization of specialized luminescence characterization techniques to provide fundamental insight into a seldom-considered luminescence property of crystalline materials such as LiYF4.

Encapsulation of nanoparticles within hexaniobate nanoscrolls presents interesting advances in the formation of nanocomposites exhibiting unique multi-dimensional properties. Building upon previous successes, facile yet versatile wet-chemical and microwave-irradiation synthetic protocols for the fabrication of a series of hexaniobate composites are presented herein. Solvothermal and, more recently, microwave-assisted methods have been developed that allow for the fabrication of peapod-like structures. During solvothermal treatment, exfoliated hexaniobate nanosheets scroll around highly ordered chains of preformed nanoparticles (NPs) to produce nanopeapods (NPPs). This approach offers versatility and high yields, in addition to the potential for advanced functional device fabrication. For the characterization of these materials, advanced techniques in atomic force microscopy (AFM) were used for investigating the surface of materials at the nanometer scale. Extensive physical, dynamic, and force modulation studies were performed on novel oxide nanocomposites by implementing particular scanning techniques to determine information such as topology, stress-induced behavior at the nanoscale, magnetic behavior, and frictional forces of the nanoscale materials. These composites were then analyzed by topological intermittent contact studies in tapping and contact mode, as well as with derivative techniques of these commonly used scanning probe approaches. In addition to studying surfaces using conventional modes of AFM, the mechanical properties of these nanocomposites were measured via dynamic lateral force modulation (DLFM) and magnetic properties of functionalized magnetic nanosheets were mapped via magnetic sampling modulation (MSM). By utilizing the capabilities of the DLFM imaging mode, elastic properties such as Young’s Modulus were measured from force-distance curves. In addition to this modulation mode, MSM was used to selectively map the vibrating magnetic nanomaterials from a modulated electromagnetic field. The information obtained from these AFM techniques can be helpful in determining the relative structural behavior of these nanocomposites and gauge their use in various applications such as structural engineering of nanoarchitectures as well as studying magnetic characteristics of metal oxide nanocomposites that exhibit characteristics different from their bulk counterparts.

The thesis aims to shed some light on the massive production of up-converting nanocrystals through solvothermal conditions. Solvothermal route allows to prepare larger quantities of these nanomaterials, as compared to normal glassware-based routes, and increase yield of nanomaterials per synthesis. The synthetic route was optimized through thorough analysis of several parameters Then, the produced nanomaterials were used to propose new optical applications in both biological (encapsulation of the nanomaterials within vesicles based on glicolypids under different pH conditions) and technological fields (the solids were entrapped within a soft-matter matrix that, under a critical temperature, underwent a sol-gel transition and permitted in a low-temperature range (below water boiling point) the modulation of matrix emissions). Lastly a microwave - assisted synthesis was studied, as alternative to solvothermal route, to understand the formation of up-converting nanocrystals, which allowed a versatile post-synthetic coating for further applications of the crystals.
La tesis abarca un problema general de producción a gran escala de los nanomateriales. Condiciones solvotermales permiten optimizar el rendimiento de producción de materiales, y por lo tanto esta ruta de síntesis ha sido elegida para su producción masiva. El proceso ha sido optimizado a través el analísis de diferentes parametros de reacción. Se han producido también aplicaciones ópticas avanzadas tanto en ámbito biológico (atrapando los sólidos en vesiculas preparadas por medio de glicolípidos a diferente pH) cuanto en ámbito tecnologico (los solidos venián atrapados en sistemas fibrilares que a raíz de una temperatura critica en la transición sol-gel permitía modulación de las emisiones de la matríz órganica). En fin se ha estudiado y analizado la formación de sistemas cristalinos por medio de la sintesis a microondas, como sistema alternativo al solvotermal, que ha resultado en la formación de nanorods con posibilidad de recubrimiento post-síntesis.

A microwave assisted methodology was developed to modify Merrifield resins (1-2% cross-linked containing 1.0-3.5 mmol Cl-/g) with different nominal molecular weights PEG (200-1000). The synthesis was also carried out by conventional heating to assess the differences between the two procedures. The most efficient synthesis was achieved by using microwave and by using PEG with molecular weight 200 and MR 2% crosslinked containing 1.25 mmol Cl -/g. The structural elucidation was carried out using Fourier transform infrared (FTIR) spectroscopy and elemental analyses. Upon pyrolsis-GC/MS analysis of the PEGylated MR, the PEG showed the tendency to undergo thermal degradation by the loss of a smaller PEG fragments. This observed degradation of PEG was less prominent during microwave assisted synthesis compared to conventional heating, in addition to faster reaction rates and higher yields. As expected, the PEGylated MR showed improved swelling properties in polar solvents. The chemical reactivity of the PEGylated Merrifield resin was confirmed by the esterification with pyruvic acid and by the substitution of hydroxyl group using thionyl chloride. In addition, the PEGylated MR was converted into (1) polymer-supported acid/base or redox indicator by the attachment of a blue organic dye - 2,6-dichloroindophenol (DCIP) through a nucleophilic substitution reaction and (2) beta-cyclodextrin trap, a water insoluble inclusion-complex, by immobilization of beta-cyclodextrin through cross-linking with 1,6-hexamethylene diisocyanate reagent.

This study was designed to develop some predictive models for the dielectric properties of the chemicals and chemical reactions and make use of dielectric properties and microwave irradiation in the chemical reactions. Specifically, the dielectric properties of the following systems were investigated at microwave frequencies of 2450 and 915 MHz: (1) C1--C5 alcohols, (2) glucose aqueous solutions, (3) lysine aqueous solutions, (4) mimicked esterification reaction model systems of parahydroxybenzoic acid with methanol, 1-propanol and 1-butanol in the presence of para-toluene sulfonic acid as a catalyst, (5) Maillard reaction model system consisting of glucose, lysine and water.
The dielectric properties of the model systems showed that they depended on the frequency applied, concentration of the material, and temperature. Most of the predictive models showed that there exists a linear or quadratic relationship between dielectric constant and concentration or temperature. However, the quadratic equation is better than the linear one to describe the variation of the loss factor with temperature or concentration.
Esterification showed great advantages for the use of microwave irradiation in chemical reaction. It included reduction in reaction time, and provided distinct temperature profiles due to microwave environment during chemical reactions. The reason for rate enhancement of this type of reaction was also demonstrated from the temperature profile.
Microwave-assisted solvent free Maillard reaction model system, consisting of glucose and lysine, demonstrated that the heating method applied was not one of the crucial factors, but the temperature level was important during the chemical reaction.
The relationship of loss factor with yield of reaction showed that it is possible to use dielectric data to analyze, and monitor the chemical reaction. It provided a new methodology to analyze the reaction.
The relationship between the loss factor, loss tangent and the reaction time, and concentration of the material showed that it is also possible to use dielectric data at microwave frequencies of 2450 and 915 MHz to study chemical reactions, especially the kinetics.

The research undertaken in this thesis includes microwave-assisted extraction (MAE), synthesis, and the investigation of the scale-up of the microwave-assisted processes with the numerical aid.
The main goal of this research is to study the various problems associated with the scale-up of the microwave-assisted extraction and synthesis processes. Laboratory studies were carried out to investigate the microwave-assisted extraction of known components from peppermint leaves and American ginseng. Various factors that influence the extraction processes were studied. Microwave-assisted extraction method was compared with conventional heating and room temperature extraction methods on the extraction of ginsenosides from American ginseng. Microwave-assisted extraction method was determined to have higher extraction rate than both room temperature extraction and reflux temperature extraction using hotplate heating indicating that there is acceleration factor in enhancing the extraction rate beyond the temperature influence.
In the study of synthesizing n-butyl paraben, microwave-assisted synthesis was observed to greatly increase the yield of n-butyl paraben in much shorter period of time compared to the classic synthesis method. A transition state theory was proposed to explain this rate enhancement. The study of the synthesis of parabens with different alcohol and the influencing factors on the synthesis of n-butyl paraben yield were also studied.
A visualization method was developed to determine the microwave distribution in a domestic microwave cavity. The method uses gypsum plate as carrier and cobalt chloride as indictor. A simulation program was developed using the finite difference time domain (FDTD) approach and written in C programming language. The program was proved to be very versatile in different type of cavity simulation. Not only cavities with different dimensions and geometrical designs can be simulated, multiple magnetrons and various ways of magnetron placement can also be integrated into the simulation program. The detailed power distribution can be visualized in a 3-D plot, and the power distribution in each layer can be analyzed using the simulation result. The power distribution information will be very useful and necessary before any real equipment development.

Le marché de l'éclairage est un marché de masse à diffusion large en pleine mutation face aux nouvelles contraintes environnementales. Il s'inscrit dans une démarche de préservation de l'environnement avec une volonté européenne de voir sa consommation énergétique réduite de 20% d'ici 2020. Les luminophores jouent un rôle prépondérant dans les performances des systèmes d'éclairage utilisant comme sources d'excitations des LEDs bleues ou UV, ou encore un plasma (Xe-Ne), où ils permettent de convertir les photons incidents (VUV, UV ou bleus) en lumière visible. Dans le cadre de cette thèse, nous nous sommes intéressés à la production de lumière blanche. Pour obtenir une couleur la plus proche du blanc idéal et répondant aux mieux au cahier des charges de l'éclairage domestique, une amélioration des performances des luminophores utilisés classiquement est nécessaire. Au cours de ces travaux nous avons porté notre attention sur deux aluminates de formulations Y3Al5O12 dopé Ce3+ (YAG :Ce) et BaMgAl10O17 dopé Eu2+ (BAM :Eu). L'aspect novateur repose d'une part sur la synthèse de ces luminophores sous forme de nanoparticules par des voies de synthèse originales (la voie solvothermale et la combustion assistée par micro-ondes respectivement) et d'autre part sur leur mise en forme (revêtements composites " luminophores/polymère "). Plusieurs techniques expérimentales (DRX, IR, Mössbauer, aimantation, MEB, MET,...) ont été utilisées afin de caractériser leurs propriétés structurales et morphologiques. L'étude des performances optiques de ces luminophores enregistrées sous excitations bleue, UV et/ou VUV nous a permis de mettre en évidence leur utilisation potentielle dans les nouveaux dispositifs d'éclairage : associés à d'autres luminophores (rouge pour le YAG :Ce; rouge et vert pour le BAM :Eu) en proportions adéquates, il est possible de générer de la lumière blanche présentant les propriétés escomptées.

Les oxydes à base de Cérium, ont fait l’objet de nombreuses études ces dernières décennies et se sont révélés des matériaux de choix, dans le domaine de la catalyse hétérogène. L’objectif à l’heure actuelle, est donc d’accroître la réactivité de ces oxydes, tout en élargissant leur gamme de températures optimales d’utilisation. Dans ce contexte particulier, il semble possible de moduler les propriétés des oxydes à base de cérium en contrôlant la morphologie des cristallites. Ce travail de thèse a donc été consacré à la détermination, l’élaboration et à la caractérisation de matériaux oxydes à base de cérium de morphologies contrôlées. Nous avons tout d’abord déterminé cristallographiquement et thermodynamiquement les morphologies accessibles au système étudié puis par traitement hydrothermale assistée par chauffage micro-ondes nous avons synthétisé les dites morphologies. Après caractérisation de la réactivité par ATG et thermographie Infrarouge nous avons optimisé ces matériaux par un dopage extrinsèque tout d’abord (dépôt de métaux précieux), puis par un dopage intrinsèque ensuite (Yttrium et Fer). Enfin, l’obtention de morphologies non accessibles cristallographiquement nous a amené à approfondir le(s) processus de germination croissance de ces particules et la forte réactivité des matériaux dopés fer nous a poussé à une caractérisation fine de la microstructure de ces matériaux. Au final nous avons pu corréler l’influence de la morphologie des cristallites sur la réactivité propre de l’ensemble des familles de matériaux étudiés
Recent decades, numerous studies on cerium-based oxides have been realized and have revealed that cerium-based oxides were materials of choice in the field of heterogeneous catalysis. The aim now is therefore to increase the reactivity of these oxides, while expanding their range of optimal temperatures of Use. In this particular context, it seems possible to modulate the properties of cerium-based oxides by controlling the morphology of the crystallites. This thesis has been devoted to the identification, development and characterization of materials based on cerium oxides of controlled morphology. We first determined possible morphologies for the studied system, by hydrothermal synthesis by micro-wave assisted heating we have synthesized these morphologies and we characterized reactivity of these materials by infrared thermography and TGA. We have optimized these materials first, by extrinsic doping (deposition of precious metals) and then by intrinsic doping (Yttrium and Iron). New morphologies have been synthesized so we have studied the processes of nucleation-growth set in. The high reactivity of iron-doped materials has led us to a detailed characterization of the microstructure of these materials. Finally correlation reactivity/morphologies of crystallites have been achieved

碩士
國立成功大學
資源工程學系碩博士班
100
In this study, a novel and facile method is developed to synthesizeTiO2nanocrystals via microwave-assisted solvothermal reaction route. Sol-gel processusing titanium isopropoxide as precursorsprepared with different solvents and hydrolysis rates are adapted to controlled the particle size and shape of TiO2nanocrystals. Well dispersed TiO2nanoparticlesin anatase phase can be obtained using the current method under 220ºC in 30 minutes. Severalexperimental parameters are found to influence the properties of nanoparticles. First-of-all, the temperature over 220 ºC is necessary to induce the crystallization of anatasenanocrystals under microwave-assisted solvothermal reaction;however the pressure (between 180 to 250 psi)and reaction time(over 15 minutes)do not show obvious effect on the variation of crystal morphology or size. In addition, a higher hydrolysis rate (H2O/Ti = 6.6) to the precursor solution generally results in smaller nanoparticles in comparison with that obtained from a lower hydrolysis rate (H2O/Ti = 3.3). Nevertheless, a crystallization is not carried out if the hydrolysis rate is too low (H2O/Ti = 1.6). The increaseof the concentration of the precursor solution does not change the resulting nanoparticlessize; however is advantageous to increase yield of product. In parallel, the solvothermal reaction undergo with different solvents allows to control not only the size but also the crystal shape due to the steric hindrance effect from the solvent. Finally,using acetic acid as chelating agent to thetitanium isopropoxide induces an anisotropic crystal growth and finally leads to rod-like anatase nanoparticles. The photocatalytic performances of the anatase nanoparticles synthesized in the current work, that all exhibit different crystal shapes and sizes, are examined by observing the degradation rate of methylene blue in water under the radiation of Xeon lamp. It is found that the anatase nanoparticles obtained by using n-propanol as solvent, showa best photocatalytic activity because of its well crystalline, high specific surface area and its wide optical range in visible light. Moreover, its preferred development of crystalline shape in {001} facet also provides more oxidization sites and is beneficial to enhance the photocatalytic activity.

Lithium-ion batteries play a crucial role in portable electronics, but require further innovation for electric vehicle and grid storage applications. To meet this demand, significant emphasis has been placed on developing safe, inexpensive, high energy density cathode materials. LiFePO₄ is a candidate cathode material for electric vehicle and grid storage applications. Vanadium-doped LiFePO₄ cathodes of the form [chemical formula] (0 ≤ x ≤ 0.25) were synthesized here by a facile, low-temperature microwave-assisted solvothermal (MW-ST) method. Such an approach offers manufacturing-energy and cost savings compared to conventional synthesis. Additionally, although [chemical formula] has been synthesized previously by conventional methods, it is shown here that the MW-ST method allows much higher doping levels than can be achieved at conventional temperatures, indicating that metastable phases can be isolated through the low-temperature microwave-assisted synthesis. LiFePO₄ suffers from poor ionic conductivity, but this limitation can be minimized by microwave-assisted synthesis through a tuning of the particle size, allowing for decreased Li⁺ diffusion paths. LiVOPO₄ is another polyanion material with higher energy density than LiFePO₄, but similar ionic conductivity limitations. It has not been previously synthesized by MW-ST. Thus, a MW-ST method was developed here to prepare LiVOPO₄. By varying reaction conditions, three polymorphic modifications of LiVOPO₄ were accessed and the electrochemical performance was optimized. LiVOPO₄ can be further discharged to Li₂VOPO₄, which has been suggested in the literature, but the structural transformation that accompanies this process has not been detailed. To this end, the delithiation process was studied by ex situ XRD measurements to better understand how the second lithium is accommodated. Finally, MW-ST has also been exploited to grow thin films of anatase TiO₂ phase on indium tin oxide (ITO)-coated glass substrates. The microwave field is selectively absorbed by the conductive ITO layer on the glass substrates, leading to ohmic heating. The resulting heated ITO layer acts as a favorable site for nucleation and growth. TiO₂ thin films have widespread applications in the energy and electronics sectors. Such selective microwave-assisted ohmic heating of solid materials within a growth solution represents a promising new avenue for microwave synthesis, which has been minimally explored in the literature.
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碩士
國立成功大學
資源工程學系
104
In this study, we used a clean and time-effective process to synthesize ultrafine TiO2 nanoparticles via sol-gel microwave-assisted solvothermal method and for the use of dye-sensitized solar cells (DSSC). TiO2 crystallite size and the major exposed crystallite facet can be tailored by using different solvents. The results revealed that using 2-pentanol (2PEN) and 3-pentanol (3PEN) had similar crystallite size; however the later exhibited preferred (001) facet that allowed a longer electron lifetime and led to a relatively higher Jsc performance. The ultrafine crystallite size of 10 nm derived by octanol (OCT) devoted to an obviously high Jsc among all the samples. In addition, OCT derived TiO2 crystallites dispersed in isopropanol (OI) and in n-propanol (ON) showed different degree of aggregation that also gave apparent effect of their DSSC performances. ON showed good dispersion and led to a quantum confinement effect. This effect resulted in a higher theoretic open circuit voltage (Voc) for the DSSC made of ON photoelectrode and showed the best power conversion efficiency up to 10.04 % with a film thickness of 14 m.

碩士
國立交通大學
應用化學系碩博士班
106
The required working voltage of WLED is small, and its brightness is high. There is no harmful mercury in WLED. In recent years, the related products have been vigorously promoted to replace the traditional incandescent lamps to achieve the effect of saving energy. Compared to tradition phosphors, luminescent QDs have high PLQY, narrow emission and tunable emissions ranging in the UV to Vis spectral range. As a result, tradition phosphors have been slowly replaced by QDs. The thrust of my master thesis is on the synthesis of zero–dimension PQDs (CsPbX3, X = Cl, Br, I) nanomaterials by microwave-assisted solvothermal method for WLED applications. Most of the PQDs with the best optoelectronic properties are synthesized by toxic lead-containing quantum dots. Hence, my study focuses on divalent cation doped colloidal CsPb1−xMxBr3 PQDs (M = Sn, Mn) featuring partial cation exchange. Finally, WLED is fabricated by using the as-prepared green and red-emitting CsPbX3 QDs as color conversion materials on 450 nm blue LED chip.

碩士
國立成功大學
資源工程學系碩博士班
101
In this study, a novel and facile method is developed to synthesize N-TiO2 mesoporous microspheres via microwave-assisted solvothermal reaction route. Sol-gel process using titanium isopropoxide as precursors, hexadecylamine as structure-directing agent, and diethylenetriamine、diethylamine、dimethylamine、trimethylamine as amine agents, respectively. The size of the microsphere was ranging from 400 to 600 nm in anatase phase can be obtained using the current method under 190℃ in 1 hour. A shift of the absorption edge to a lower energy and a stronger absorption in the visible light region were observed. Both substitutional and interstitial nitrogen-doped titanium dioxides were prepared. Their surface states were clarified by XPS spectra. The nitrogen bonding form changed from different N/Ti ratio and different amine agents, and the specific surface area、photodegradation was different. The results of photodegradation or the organic pollutant rhodamine B in the visible light irradiation (420 nm) suggested that the TiO2 photocatalysts after nitrogen doping were greatly improved compared with Degussa P-25. The results showed that the photodegradatio, and the trimethylamine (N/Ti ratio =0.9)was obviously prior to others N-doped TiO2, because its interstitial is the height in N-doped TiO2 sample. Moreover, the visible light activity of interstitial N-doped TiO2 is higher than that of substitutional N-doped TiO2 .

A series of interesting core/shell silver/phenol formaldehyde resin (PFR) nano/microstructures were also synthesized through an efficient microwave process by self-assembly growth. Various morphologies, including monodispersed nanospheres, nanocables, and microcages were obtained by changing the fundamental experimental parameters, such as the reaction time and the surfactants (Pluronic P123 or CTAB). The results indicated that the presence of triblock copolymer Pluronic P123 would result in hollow silver/PFR microcages, while CTAB would prefer the formation of ultralong silver/PFR coaxial nanocables. In the absence of surfactants, monodispersed core/shell silver/PFR nanospheres could be obtained. The size of the nanospheres can be controlled in the range of 110 to 450 nm by changing the molar ratio of reagents (phenol:hexamine). The morphology and composition of the as-prepared products were characterized. The formation mechanism of the products was discussed based on the obtained results.
Bifunctional mesoporous core/shell Ag FeNi3 nanospheres were synthesized by reducing iron(III) chloride, nickel(II) chloride and silver nitrate with hydrazine in ethylene glycol under microwave irradiation. The efficient microwave-hydrothermal process significantly shortened the synthesis time to one minute. The toxicity of Ag FeNi3 nanospheres were tested by exposing to zebrafish, they were less toxic than silver nanoparticles. In vitro MRI confirmed the effectiveness of the Ag FeNi3 nanospheres as sensitive MRI probes. The interaction of Rhodamine Band nanospheres showed greatly enhanced fluorescence over the FeNi3 nanoparticles.
Finally, a series of ZnO microarchitectures including monodispersed spindles, branches, flowers, paddies, and sphere-like clusters were prepared by an efficient microwave-hydrothermal process. The ZnO mophologies could be effectively controlled by changing the reaction conditions such as the reaction temperature, the reactant concentrations and the solvent system. Simple microspindles, interesting flowers and paddies could be obtained in the presence of hexamine, and the more attractive sphere-like clusters could be synthesized by introducing phenol. The formation mechanisms of different morphologies are discussed in detail. These interesting ZnO structures may have potential applications in electronic and optoelectronic devices.
Inorganic nanostrucured materials have attracted much attention owing to their unique features and important applications in biomedicine. This thesis describes the development of rapid and efficient approaches to synthesize inorganic nanostructures, and introduces some potential applications.
Magnetic nanostructures, such as necklace-like FeNi3 magnetic nanochains and magnetite nanoclusters, were synthesized by an efficient microwave-hydrothermal process. They were used as magnetic resonance imaging (MRI) contrast agents. Magnetic FeNi3 nanochains were synthesized by reducing iron(III) acetylacetonate and nickel(II) acetylacetonate with hydrazine in ethylene glycol solution without any template under microwave irradiation. This was a rapid and economical route based on an efficient microwave-hydrothermal process which significantly shortened the synthesis time to mins. The morphologies and size of the materials could be effectively controlled by adjusting the reaction conditions, such as, the reaction time, temperature and concentrations of reactants. The morphology and composition of the as-prepared products were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The size of the aligned nanospheres in the magnetic FeNi 3 chains could be adjusted from 150nm to 550nm by increasing the amounts of the precursors. Magnetic measurements revealed that the FeNi3 nanochains showed enhanced coercivity and saturation magnetization. Toxicity tests by exposure of FeNi3 nanochains to the zebrafish larvae showed that the as-prepared nanochains were biocompatible. In vitro magnetic resonance imaging (MRI) confirms the effectiveness of the FeNi 3 nanochains as sensitive MRI probes. Magnetite nanoclusters were synthesized by reducing iron(III) acetylacetonate with hydrazine in ethylene glycol under microwave irradiation. The nanoclusters showed enhanced T2 relaxivity. In vitro and in vivo MRI confirmed the effectiveness of the magnetite nanoclusters as sensitive MRI probes. We also investigated the biodistribution of the nanoclusters in rat liver and spleen.
Jia, Juncai.
Adviser: Jimmy C. Yu.
Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: .
Thesis (Ph.D.)--Chinese University of Hong Kong, 2011.
Includes bibliographical references.
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.

Thesis (Ph.D.)--York University, 2008. Graduate Programme in Chemistry.
Typescript. Includes bibliographical references (leaves 136-150). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR51683

博士
國立交通大學
應用化學系所
98
Owing to the features of a high surface-to-volume ratio, magnetic property, absorption capacity in the broad range of electromagnetic spectrum, and ease of modification, iron oxide magnetic nanoparticles (Fe3O4 MNPs) can be readily designed to have multiple functions for suiting the use in the development of analytical methods. Additionally, Au NCs with good water solubility, excellent stability, and low toxicity have been discovered to be suitable for use in analytical and biomedical researches. In this thesis, two major topics based on the fabrication and the use of Fe3O4 MNPs and gold nanoclusters for method developments and applications were explored. In the first part of this thesis, an affinity based mass spectrometry using Fe3O4 MNPs as the assisting materials for surface-assisted laser desorption ionization mass spectrometry (SALDI MS) and affinity probes for biomolecules was proposed. After the target species trapped by the Fe3O4 MNPs, the NP-target species conjugates can be rapidly isolated by external magnetic field followed by addition of citrate salts. The mixtures were then directly subjected into a mass spectrometer for SALDI MS analysis. Therefore, the sample loss can be avoided. Additionally, this approach can avoid the problems such as sweet spots that are generally observed in conventional matrix-assisted laser desorption/ionization (MALDI) MS analysis. The upper detectable mass is approximately 16 kDa. Next, microwave-assisted extraction of DNA and phosphopeptides and microwave-assisted protein enzymatic digestion were developed in this work using functionalized Fe3O4 MNPs as the affinity probes and microwave-heating absorbers. This work demonstrated that the presence of Fe3O4 MNPs in solutions under microwave-heating can accelerate the heating rate. On the basis of quick heating rate, traces of DNA can be effectively enriched by the C18-funcationzliazed Fe3O4 MNPs from aqueous solutions under microwave-heating within 30 sec. Furthermore, the results demonstrated that this approach is suited for enriching DNA from saturated aqueous sodium chloride. Additionally, traces of phosphopeptides from complex samples were also demonstrated to be readily enriched by Fe3O4/ZnO core/shell (Fe3O4@ZnO) MNPs under microwave-heating for 30 sec. In addition, protein enzymatic digestion was accelerated in the presence of functionalized Fe3O4 MNPs under microwave-heating for 60 sec. The feasibility of using trypsin-bound Fe3O4 MNPs was also demonstrated to be applicable in this approach. In the last part of this work, protein directed synthesis of Au NCs was studied by examining several proteins including bovine serum albumin (BSA), lysozyme, immunoglobulin G (IgG), concanavalin A (con A), cytochrome C, myoglobin, and ovalbumin as the reducing agents. The results show that the presence of cysteine in the protein sequences critical for the generation of Au NCs. Furthermore, lysozyme directed generation of Au NCs (Au@lysozyme NCs) remain their antibiotic activities. To reduce the reaction time, microwave-assisted synthesis of AuNCs by reacting proteins with tetrachloroauric(III) acid under microwave-heating within a short of period (5 min × 8) was proposed. The generated Au@lysozyme NCs also remain their antibiotic activities. It has been demonstrated that the NCs can be used to effectively inhibit the cell growth of pathogenic bacteria including antibiotic-resistant bacteria including vancomycin-resistant Enterococcus faecalis and pan-drug resistant Acinetobacter baumannii. Furthermore, the minimum inhibition concentrations of the proteins on Au@lysozyme NCs for these bacteria were much lower than those when free lysozyme was used.

博士
國立中正大學
化學所
98
There are two major subjects discussed in this thesis. The first part is the study of synthesis and structural characterization of organophosphorous catalysts in both their molecular forms and supported forms on gold nanoparticles (Au NPs) and silicic acid polymer. Their catalytic reactivity towards various dehydrochlorinative Si-C coupling reactions, Diels-Alder reactions and thioacetalization condensation reactions of aldehydes with dithiols were also studied. Spherical Au NPs of an average diameter of 2.3 nm were used as catalyst supports. These Au NPs were synthesized by the chemical reduction method using NaBH4 as the reducing agent to reduce HAuCl4‧3H2O in the presence of CH3(CH2)7SH stabilizer. The compound HS(CH2)11P+(2-py)3I- (6), which was derived from Br(CH2)11OH was specially designed as the linker to connect molecular organophosphorous catalysts and Au NPs surfaces. The thiol end (HS) of the anchoring linker can be put onto Au NPs surfaces by the ligand exchange method at room temperature to give Au NPs-SH(CH2)11P+(2-py)3I- (7). The reaction of CH2=CH(CH2)9Br (2) with sodium iodide in acetone at reflux afforded CH2=CH(CH2)9I (9) as product. The 1-iodo-11-trimethoxyundecane (OMe)3Si(CH2)10CH2I (11) was synthesized by functionalizing the terminal double bond of compound 9. The iodide-terminated alkyl siloxane ○P-(O)3-Si(CH2)10CH2I (12), where ○P = poly(silicic acid), was prepared by the acid-catalyzed condensation polymerization of compound 11. The polymeric SiO2-supported organophosphorous complex catalysts TMS-○P-(O)3-Si(CH2)10CH2P+(2-py)3I- (14) was synthesized by the direct reaction of P(2-py)3 and the polymer TMS-○P-(O)3-Si(CH2)10CH2P+I- (13). Both 7 and HO(CH2)11P+(2-py)3 I- (8) were proved to be effective catalysts for a series of C－X (X = C, Si and S) coupling reactions. With a catalyst loading of 3 mole% of 7 or 8, a series of Diels-Alder and thioacetalization condensation reactions can be completed in hours at room temperature to give the corresponding products in high yields. Also, the catalytic dehydrochlorinative reactions using 5 mole% of 7 or 8 gave Si－C coupling products in good to excellent yields (66-98%). In addition, 7-catalyzed C－C and Si－C coupling reactions can be further accelerated under microwave irradiation conditions to give desired products of 82-94% yields within 25-120 seconds. Since all metals conduct microwave very effectively, the flash heating effect on the Au metal cores of Au NPs-supported catalysts would be much more intense than other organics, inorganic complexes and solvents under microwave irradiation conditions. Consequently, the catalytic reactivity and efficiency of Au NPS-supported organophosphorous catalysts can be much further enhanced due to the formation of the microwave-heated Au NPs “hot spots”. As a result, the catalytic reactivity of Au NPs-bound organophosphorous catalyst 7 on Diels-Alder reactions was more efficient than its unbound molecular counterparts 8 (20% higher in yield) and those of the SiO2-bound catalyst 14 (10% higher in yield). More importantly, the Au NPs-supported organophosphorous 7-catalyzed Diels-Alder reaction of cyclopentadiene and methyl vinyl ketone can be recycled 15 times without significant loss in reactivity. In additions, the Au NPs-supported catalyst Au-SH(CH2)11NHOP(2-py)2 (23) and its molecular form HO(CH2)11NHOP(2-py)2 (19) were synthesized to be used as catalysts for a series of Witting reactions. It was demonstrated that with a catalyst loading of ¬¬10 mol% of 19 or 23 the reaction at 110 oC for 18 hours gave Wittig reaction products in high yields (up to 80%). The second part of the thesis aimed at the synthesis and application of organometallic Lewis acids, [P(2-py)3M(CO)(NO)2](BF4)2, where M = Mo (7) and W (8) as well as [N(CH2-2-py)3M(CO)(NO)2](BF4)2, where M = Mo (10) and W (11). Both 8 and 11 were proved to be effective catalysts for [2+2+2] aldehyde cyclotrimerization reactions. Moreover 11-catalyzed Diels-Alder and Friedel-Crafts reactions and 10-catalyzed Pechmann reactions also gave excellent yields. With the employment of as little as 0.3 mol% of catalysts 8 or 11, [2+2+2] aldehyde cyclotrimerization reactions were efficiently performed in a solvent-less system to give corresponding trioxane products in good to excellent yields (30-99%). The catalytic Diels-Alder, Friedel-Crafts and thioacetalization condensation reactions using 3 mole% of 11 as the catalyst can be carried out efficiently in a solvent-less system to give C－C coupling products in good to excellent yields (50-98%). The catalytic Pechmann reactions in the presence of 1 mole% of 10 proceeded proficiently in a solvent-less system to give products in good to excellent yields (83-95%). The [2+2+2] aldehyde cyclotrimerization reactions were further accelerated under microwave irradiation (300 W) conditions in the presence of 0.3 mol% of 8 and two drops (0.025 mL) of [bmim][PF6], where bmim = 1-butyl-3-methylimidazolium. Also, an apparent shift in chemical equilibrium was observed for these microwave-assisted cyclotrimerization reactions to significantly increase the product yields of trioxanes. Finally, both the 8- and 11-catalyzed [2+2+2] cyclotrimerization of 3-cyclohexene-1-carboxaldehyde can be effectively recycled up to 26 runs for 8 and 20 runs for 11 with a conversion maintained at ＞80%.