Thesis (Ph. D.)--State University of New York at Binghamton, Department of Chemistry, 2007. / Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

No description available.

M.Tech. / Among the materials being used for gas sensors, metal oxides are the most important materials because of their potential to detect many gases at low concentrations. Nevertheless, sensors made of metal oxide need to be operated at high temperatures (above 200°C) and have a weak sel ectivity. In order to overcome this difficulty, the materials are being investigated for gas sensing applications. Carbon nanotubes (CNTs) are promising materials with unique properties, such as high electrical conductivity, mechanical strength, nanometer–scale sizes, and high aspect ratio. Their adsorption ability and high surface area make them attractive as gas sensing materials, which have been intensively studied. CNTs can be used solely or combined with metals and oxides materials in order to constitute efficient gas sensors. In the present research, multi–walled CNTs (MWCNTs) were coated with tin dioxide (SnO2) and incorporated into two epoxy resins with widely different mechanical properties in order to study the effect of CNTs on the morphology, mechanical, electrical, and sensing properties of the composites. In the MWCNT/polymer composite study, Epon 828 was used as the polymer matrix and D–2000 (which gives rubbery composites) and T–403 (which gives glassy composites) as the hardeners. Composite were prepared with 0.1 wt.% MWCNTs in an epoxy matrix. Pristine MWCNTs (MWCNTs not treated with any acid and therefore used as received) and SnO2–MWCNTs were used for comparison and a two–step curing procedure was used with initial temperature set at 75°C for 3 hours, followed by additional 3 hours at 125°C. The sample s were characterized for morphology, mechanical, thermo–mechanical and electrical properties using scanning electron microscopy (SEM), an Instron tensile tester, dynamic mechanical analysis (DMA) and Cascade Microtech four–point probe, respectively. In both cases, strong covalent bonds were created as a bridge between the CNTs and matrix, but due to differences in viscosity, the nanotubes dispersion was much better in the rubbery epoxy resin than in the glassy epoxy resin. A 77% increase in tensile modulus was observed in the rubbery system using 0.1 wt.% SnO2–MWCNTs compared to the neat rubbery epoxy. As for the glassy epoxy based composite, only a 3% improvement in tensile modulus could be observed. In addition to the mechanical properties, the presence of CNTs has demonstrated a material with high vi electrical conductivity. But for the surface measurements during the gas sensing analysis, the conductivity was very low for the composites to be used for this application as envisioned. MWCNTs coated with SnO2 nanoparticles used in the present study, were synthesized by a microwave synthesis method. The composite samples were characterized by X–ray diffraction (XRD), Raman spectroscopy, high resolution transmission electron microscopy (HRTEM), scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR) and Brunauer–Emmet–Teller (BET) surface area analysis. These techniques gave evidence for surface and chemical modifications of the synthesized composites. The results showed microwave synthesis to be a very efficient method in producing CNTs that are densely coated and well dispersed with SnO2 nanoparticles in a very short time (total reaction time of 10 minutes). Microwave synthesis is particularly interesting because of the energy used, the higher temperature homogeneity and the shorter reaction times led to nanoparticles with high crystallinity and a narrow particle size distribution. Controlling the morphology by varying synthesis conditions such as temperature, pressure and time is also possible.

No description available.

by Yip Yeuk Lan = 已發生液態調幅分離的過冷「鈀八十二硅十八」合金熔融體的結晶行為 / 葉若蘭. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 51-52). / Text in English; abstracts in English and Chinese. / by Yip Yeuk Lan = Yi fa sheng ye tai diao fu fen li de guo leng "ba ba shi er gui shi ba" he jin rong rong ti de jie jing xing wei / Ye Ruolan. / Acknowledgments --- p.ii / Abstract --- p.iii / 摘要 --- p.iv / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Introduction / Chapter 1.2 --- Properties of Nanocrystalline Materials / Chapter 1.3 --- Fabrication of Nanocrystalline Materials / Chapter 1.4 --- Fabrication of Nanocrystalline Material by Spinodal Decomposition / Chapter 1.5 --- Aim of the Thesis / References / Figures / Chapter Chapter 2 --- Experimental --- p.28 / Chapter 2.1 --- Introduction / Chapter 2.2 --- Preparation of Fused Silica Tubes / Chapter 2.3 --- Sample Preparation / Chapter 2.4 --- Sample Preparation for Microstructure Analysis / Chapter 2.5 --- Microstructure Characterization by TEM / Chapter 2.6 --- Annealing a TEM sample / References / Figures / Chapter Chapter 3 --- Results and Discussions --- p.44 / Results / Discussions / References / Figures

Wu Ling. / "Dec 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

分層次的多孔材料在自然界中非常廣泛的被發現，例如動物的肺部、樹葉以及矽藻的骨骼。最近一些年，大孔(macropores)連同介孔(mesopores)或者(或與)微孔(micropores)等結構的分層次的多孔材料的製備與合成吸引了材料化學領域諸多的注意力，以期他們在催化、吸附解附、藥物釋放、感測器以及組織工程等多種方向中發揮潛在的應用。 / 本論文中我們將介紹一種簡單而靈活的的基於微粒穩定的高內相乳液(Particle-stabilized high internal phase emulsion)的方法，製備得到具有分層次多孔結構的二氧化鈦材料，擁有增強的光催化活性。由微凝膠軟球和二氧化鈦硬球共同作用，我們得到穩定的水包油高內相乳液體系。在除去液體相時將會促使形成幾十微米的大孔結構，約十微米的介孔連通窗格，以及分佈在大孔壁上的約一百納米的微孔，這三種不同尺寸的孔隙結構在三維方向上互相連通。初始合成的二氧化鈦材料由掃描電子顯微鏡(SEM)，X射線衍射(XRD)，壓汞儀來表徵其内部結構，同時測試其相對應的羅丹明光降解效率。結果清晰地顯示，微粒穩定的範本法可以成功的形成擁有多種且互不相同的多層次多孔結構。同時這種具有大孔和微孔的多層次孔隙結構的二氧化鈦材料，表現出非常有效的光化學催化性質，顯示了其在分離、淨化等過程的巨大潛在應用價值。 / Hierarchical porous materials occur widely in nature, including for example the lungs of animals, the leaves of trees, and diatom skeletons. In recent years, the synthesis of new hierarchical porous materials containing macroporous along with micro-and/or mesoporous has attracted considerable attention in material chemistry, because of their potential use in diverse applications such as catalysis, adsorption and separations, drug delivery, sensors and tissues engineering. / In this thesis, we present a simple and flexible method to synthesize hierarchically porous structured titania with enhanced photocatalytic activity using particle-stabilized high internal phase emulsions (Pickering HIPEs). Starting with a highly concentrated emulsion stabilized by both soft microgels and TiO₂solid nanoparticles, three-dimensionally interconnected porous titania materials with ordering on three different scales, that is, macroporous (~50μm), interconnected throat (~10μm), and nanoporous walls (~100 nm), are successfully obtained after drying and sintering. The so-prepared materials are characterized by scanning electron microscopy (SEM), X-ray diffraction, mercury intrusion, and the corresponding photocatalytic activity is evaluated by measuring the photodegradation of Rhodamine B in water. Our results clearly show that particle-stabilized emulsion templating can successfully lead to hierarchical porous material with multiple and discrete pore scales. Moreover, these hierarchically porous TiO₂ containing macroporous along with nanopores walls can be very efficient photocatalysts, suggesting their great potential applications in separation and purification process. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Li, Xiaodong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references. / Abstracts also in Chinese. / 摘要 --- p.I / Abstract --- p.II / Tableof Contents --- p.III / Acknowledgement --- p.VI / Chapter Chapter 1 --- Introduction to Porous Materials: Design, Synthesis and Applications --- p.1 / Chapter 1.1 --- Hierarchical Porous Materials in Nature --- p.1 / Chapter 1.2 --- Artificial Hierarchical Porous Materials --- p.2 / Chapter 1.3 --- Non-Templating Methods --- p.3 / Synthesis of Hierarchical Porous Materials with Single Composition --- p.5 / Chapter 1) --- meso-macroporous zirconium oxides --- p.5 / Chapter 2) --- meso-macroporous titanium oxides --- p.6 / Synthesis of Hierarchical Porous Materials with Multiple Composition --- p.9 / Chapter 1.4 --- Templating Methods --- p.10 / Chapter 1.5 --- Combination of Template and Non-template Methods --- p.12 / Chapter 1.6 --- Potential Application of Porous Materials --- p.13 / HPLC separation --- p.13 / Hierarchical catalysis --- p.14 / Electrode materials for fuel cell applications --- p.15 / Biomaterials engineering --- p.15 / Chapter 1.7 --- Objective of the Research --- p.16 / Chapter References --- p.18 / Chapter Chapter 2 --- Preparation of Hierarchically Structured TiO₂ Using High Internal Phase Emulsions (HIPEs) Stabilized by Binary Nanoparticles as the Templates --- p.22 / Chapter 2.1 --- Introduction to Particle Stabilized HIPEs --- p.22 / Chapter 2.2 --- Experiment Part --- p.26 / Chapter 2.2.1 --- Materials --- p.26 / Chapter 2.2.2 --- pNIPAM-co-MAA microgels synthesis and Characterization --- p.26 / Chapter 2.2.3 --- Synthesis of Hierarchical Porous TiO₂ Materials templating from HIPEs Stabilized by Binary Nanoparticles --- p.29 / Chapter 2.3 --- Results and Discussion --- p.32 / Chapter 2.3.1 --- HIPEs Stabilized Solely by Microgel Particles --- p.32 / Chapter 2.3.2 --- HIPEs Stabilized by Binary Nanoparticles --- p.35 / Chapter 1) --- Sintering effect on the porous TiO₂ monolith --- p.40 / Chapter 2) --- Microgel/TiO₂ ratio effect on the porous materials --- p.45 / Chapter References --- p.52 / Chapter Chapter 3 --- Photo-Catalytic Activity of the TiO₂-based Hierarchically Structured Porous Materials --- p.54 / Chapter 3.1 --- Introduction --- p.54 / Chapter 3.2 --- Experiment Section --- p.55 / Chapter 3.3 --- Result and Discussion --- p.56 / Chapter 1) --- Influence of sintering temperature on the porous materials --- p.56 / Chapter 2) --- Influence of internal phase volume fraction on the photocatalytic activity . --- p.59 / Reference --- p.63 / Chapter Chapter 4 --- Conclusion --- p.64

Lam, Ngai Sze. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / Lam, Ngai Sze. / Abstract --- p.i / Acknowledgements --- p.iii / Table of contents --- p.iv / List of Figures --- p.viii / List of Tables --- p.xiii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.1.1 --- Properties of CdSe --- p.1 / Chapter 1.1.2 --- Synthesis of CdSe one-dimensional (ID) nanostructure --- p.5 / Chapter 1.1.3 --- Application of CdSe nanostructures --- p.8 / Chapter 1.1.4 --- Significance of surface engineering --- p.10 / Chapter 1.1.4.1 --- Surface passivation --- p.11 / Chapter 1.1.4.2 --- Surface functionalization --- p.11 / Chapter 1.1.4.3 --- Modulation of optical/electrical properties --- p.12 / Chapter 1.2 --- Present study --- p.14 / Chapter 1.2.1 --- Objective --- p.14 / Chapter 1.2.2 --- General methodology --- p.14 / Chapter Chapter 2 --- Instrumentation --- p.19 / Chapter 2.1 --- Introduction --- p.19 / Chapter 2.2 --- Setup of Sample Preparation --- p.19 / Chapter 2.2.1 --- Synthesis --- p.19 / Chapter 2.2.1.1 --- Thermal evaporation apparatus --- p.19 / Chapter 2.2.1.2 --- Microwave assisted chemical synthesis --- p.21 / Chapter 2.2.2 --- Sample handling --- p.22 / Chapter 2.2.3 --- Other treatments --- p.22 / Chapter 2.3 --- X-ray photoelectron spectrometer (XPS) --- p.22 / Chapter 2.3.1 --- Basic Principle --- p.22 / Chapter 2.3.2 --- Instrumentation --- p.24 / Chapter 2.3.3 --- Charging problem --- p.27 / Chapter 2.3.4 --- Qualitative analysis --- p.27 / Chapter 2.3.5 --- Quantitative analysis --- p.28 / Chapter 2.3.5.1 --- Curve fitting --- p.28 / Chapter 2.3.5.2 --- Atomic percentage --- p.29 / Chapter 2.3.5.3 --- Thickness determination --- p.29 / Chapter 2.4 --- Photoluminescence --- p.30 / Chapter 2.4.1 --- Basic principle --- p.30 / Chapter 2.4.2 --- Instrumentation --- p.31 / Chapter 2.5 --- Other equipments --- p.32 / Chapter Chapter 3 --- Synthesis of CdSe Nanorods --- p.34 / Chapter 3.1 --- Introduction --- p.34 / Chapter 3.2 --- Thermal evaporation --- p.34 / Chapter 3.2.1 --- Experimental procedures --- p.34 / Chapter 3.2.2 --- Characterization --- p.35 / Chapter 3.3 --- Microwave assisted method --- p.41 / Chapter 3.3.1 --- Experimental procedures --- p.41 / Chapter 3.3.2 --- Characterization --- p.42 / Chapter 3.4 --- Summary --- p.47 / Chapter Chapter 4 --- Surface Treatment of CdSe Nanorods --- p.49 / Chapter 4.1 --- Introduction --- p.49 / Chapter 4.2 --- Experimental procedures --- p.50 / Chapter 4.3 --- Results and Discussion --- p.51 / Chapter 4.3.1 --- Formation of Se-coated CdSe NRs --- p.51 / Chapter 4.3.2 --- Desorption and thinning --- p.56 / Chapter 4.3.3 --- Surface degradation --- p.67 / Chapter 4.4 --- Summary --- p.69 / Chapter Chapter 5 --- Surface Capping of CdSe Nanorods --- p.73 / Chapter 5.1 --- Introduction --- p.73 / Chapter 5.2 --- Experimental procedures --- p.73 / Chapter 5.3 --- Results and Discussion --- p.74 / Chapter 5.3.1 --- Capping of thiol with halo-functional group --- p.74 / Chapter 5.3.1.1 --- Compositional analysis --- p.75 / Chapter 5.3.1.2 --- PL analysis --- p.79 / Chapter 5.3.2 --- Capping of DNA --- p.81 / Chapter 5.3.2.1 --- Compositional analysis --- p.81 / Chapter 5.3.2.2 --- PL analysis --- p.83 / Chapter 5.4 --- Summary --- p.92 / Chapter Chapter 6 --- Conclusions and Future Work --- p.94 / Chapter 6.1 --- Conclusions --- p.94 / Chapter 6.2 --- Future work --- p.95