The superior properties of carbon nanotubes (CNTs) are best manifest in bulk materials when the CNTs are organized in tandem and embedded in a continuous matrix. Decorating the CNTs with magnetic nanoparticles (MNPs) facilitates their expedient organization with a magnetic field. One of the most convenient methods for their decoration is to first treat the CNTs with oxidative acids, and then coprecipitated MNPs in situ. This method results magnetized CNTs that are covalently functionalized with the MNPs. The associated destruction in the CNTs required running a comparative study of this protocol to identify the influence of the acid treatment on the decoration of multiwalled CNTs (MWNTs). Further, we explore means to tune the physical properties of these magnetized CNTs (mMWNTs) by varying the (1) MNP material composition, and (2) MNP:MWNT (w/w) magnetization weight ratio (γ). The resulted composite materials (mMWNTs) are utilized to synthesize a novel and hitherto unreported class of colloidal suspensions (MCCs) for which the dispersed phase, which consists of MWNTs decorated with MNPs, is both magnetoresponsive and electrically conductive. Synthesis of the dispersed phase merges processes for producing ferrofluids and mMWNTs. Later, these MCCs are adapted and engineered to produce a biological ink containing MWNTs that are twice functionalized, first with MNPs and thereafter with the anti-c-Myc monoclonal antibodies (Abs). The ink is pipetted and dynamically self-organized by an external magnetic field into a dense electrically conducting sensor strip that measures the decrease in current when a sample containing c-Myc antigens (Ags) is deposited on it. On the other side, a nondestructive methods to magnetize MWNTs and provide a means to remotely manipulate them is through the electroless deposition of magnetic nickel nanoparticles on their surfaces. The noncovalent bonds between Ni nanoparticles and MWNTs produce a Ni-MWNT hybrid material (NiCH) that is electrically conductive and has an enhanced magnetic susceptibility and elastic modulus. Raising γ (Ni:MWNT weight ratios) increases the coating layer thickness, which influences the NiCH magnetic properties and tunes its elastic modulus. The NiCH was used to fabricate Ni-MWNT macrostructures and tune their morphologies by changing the direction of an applied magnetic field. Leveraging the hydrophilic Ni-MWNT outer surface, a water-based conductive ink was created and used to print a conductive path that had an electrical resistivity of 5.9 Ωm, illustrating the potential of this material for printing electronic circuits. Further, the NiCHs are introduced into an epoxy matrix at low 0.25-1% volume fractions and aligned along the direction of an applied magnetic field, which produces anisotropic bulk properties. However, nanoparticles aligned in perpendicular directions in sequential layers result in an effectively isotropic composite material. Furthermore, the subsequent annealing of the NiCH in the presence of air oxidizes nickel to nickel oxide whereas carbon is released as gaseous carbon dioxide, which leads to a novel approach for the fabrication of nickel oxide nanotubes (NiONTs) based on MWNTs as a sacrificial template. New chelating polyelectrolytes are used as dispersing agents to achieve high colloidal stability both for NiCH and NiONTs. A gravimetric specific capacitance of 245.3 F g-1 and areal capacitance of 3.28 F cm-2 at a scan rate of 2 mV s-1 is achieved with an electrode fabricated using nickel oxide nanotubes as the active element with a mass loading of 24.1 mg/cm2. / Thesis / Doctor of Philosophy (PhD) / The superior properties of carbon nanotubes (CNTs) are best manifested in bulk materials when the CNTs are organized axially and in tandem, and embedded in a continuous matrix. Decorating the CNTs with magnetic nanoparticles (MNPs) facilitates their organization through “action from a distance” with a magnetic field. The attachment of MNPs to the surfaces of CNTs can be realized through covalent or non-covalent (i.e. physical) bonding. This work develops both methodologies to investigate how the physical properties of magnetized CNT (mCNT) can be tuned and produce new CNT-based nanostructures for particular applications. First, mCNTs are utilized to synthesize a hitherto unreported class of colloidal suspensions based on which a magnetic bio-ink is fabricated to print a fast-response biological sensor. Next, nickel-coated CNTs prepared using electroless deposition are used in the form of a filler at low volume fractions in an epoxy matrix, where they are aligned along multiple-direction using a magnetic field, producing either anisotropic or isotropic bulk properties on demand. Finally, subsequent annealing of nickel-coated CNTs in air oxidizes nickel to nickel oxide while carbon is released in the form of gaseous carbon dioxide. This leads to another novel approach for the fabrication of nickel oxide nanotubes, which are demonstrated to be an alternate viable material to fabricate electrodes for use in supercapacitors.

A novel fiber optic structure, termed stochastic ordered hole fibers, has been developed that contains an ordered array of six hollow tubes surrounding a hollow core, combined with a nanoporous glass creating a unique fully three dimensional pore/fiber configuration. The objective of this study is to increase the functionality of these stochastic ordered hole fibers, as well as porous clad fibers, by integrating electronic device components such as conductors, and semiconductors, and optically active materials on and in the optical fiber pore structures. Conductive copper pathways were created on/in the solid core fibers using an electroless deposition technique. A chemical vapor deposition system was built in order to attempt the deposition of silicon in on the porous clad fibers. Additionally, conductive poly(3,4-ethylenedioxythiophene)- poly(styrene sulfonate) (PEDOT:PSS) and photoactive polymer blend poly(3- hexylthiophene) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-)6,6)C61 (P3HT: PCBM) were deposited on the fibers using dip coating techniques. Quantum dots of Cadmium Selenide (CdSe) with particle sizes of ranging from 2- 10 nm were deposited in the stochastic ordered hole fibers. SEM and EDS analysis confirm that copper, polymer materials, and quantum dots were deposited in the pore structure and on the surface of the fibers. Finally, resistance measurements indicate that the electrolessly deposited copper coatings have sufficient conductivity to be used as metallic contacts or resistive heating elements. / Master of Science

xv, 101 p. ; ill. (some col.) A print copy of this title is available through the UO Libraries under the call number: KNIGHT QC176.84.E5 P47 2007 / Silver films with nanoscale to mesoscale thicknesses were produced by chemical reduction onto silica substrates and their physical and electrical properties were investigated and characterized. The method of silver deposition was developed in the context of this research and uses a single step reaction to produce consistent silver films on both flat silica coverslips and silica nanospheres of 250-1000 nm. Both the structure and the electrical properties of the silver films are found to differ significantly from those produced by vacuum deposition. Chemically deposited (CD) silver is not uniformly smooth, but rather is granular and porous with a network-like structure. By quantitatively accounting for the differences in scale, geometry, and microstructure of the CD films, it is found that the same models used to describe the resistivity of vacuum deposited films may be applied to CD films. A critical point in the analysis that allows this relation involves the definition of a geometric parameter, g, which replaces the thickness, t, as the critical length that influences the electrical properties of the film. The temperature dependent properties of electrical transport were also investigated and related to the microstructure of the CD films. A detailed characterization of CD silver as shells on silica spheres is also presented including physical and optical properties. In spite of the rough and porous morphology of the shells, the plasmon resonance of the core-shell structure is determined by the overall spherical shell structure and is tunable through variations in the shell thickness. Preliminary investigations into the electrical transport properties of aggregates of silver coated spheres suggest similarities in the influence scale, geometry, and microstructure to silver films on flat substrates. The aggregates of shells also exhibit pressure related resistance behavior due to the composite structure. / Adviser: Miriam Deutsch

This master’s thesis is focused on corrosion resistance of nickel-phosphorus coatings on magnesium alloy AZ91. In the theoretical part is summarized current knowledge about magnesium alloys and electroless deposition of Ni-P coatings including ongoing reactions. Theoretical part also lists all substances contained in the nickel bath and their specific use there. In the second half of theoretical part are discussed corrosion and immersion tests. Theoretical part is ended by review aimed towards the research in areas of immersion tests. Experimental part describes individual steps of pretreatment on magnesium alloy and then deposition of the Ni-P coating. Composition and morphology of deposited Ni-P coating and magnesium alloy were studied using energy dispersive spectroscopy. Experiment part also contains list of experiments trying to figure out ideal thickness of low-phosphorus coating which is able to protect magnesium alloy from corrosion. Master’s thesis is ended with the list of immersion tests and results which outcomes from them.

To investigate conditions of silver electroless deposition on silicon (100), optical microscope, atomic force microscope (AFM) and attenuated total reflection infrared spectroscopy (ATR-FTIR) spectroscopy were used. Twenty second dipping in 0.8mM AgNO3/4.9% solution coats a silicon (100) wafer with a thin film of silver nanoparticles very well. According to AFM results, the diameter of silver particles is from 50 to 100nm. After deposition, arithmetic average of absolute values roughness (Ra) increased from ~0.7nm to ~1.2nm and the root mean square roughness (Rq) is from ~0.8nm to ~1.5nm. SCN- ions were applied to detect the existence of silver on silicon surface by ATR-FTIR spectroscopy and IR spectra demonstrate SCN- is a good adsorbent for silver metal. Patina is the general name of copper basic salts which forms green-blue film on the surface of ancient bronze architectures. Patina formation has been found on the surface of platinum or ruthenium after several scans of cyclic voltammetry in 2mM CuSO4/0.1M K2SO4, pH5 solution. Evidence implies that oxygen reduction reaction (ORR) triggers the patina formation. ORR is an important step of fuel cell process and only few sorts of noble metals like platinum can be worked as the catalyst of ORR. Mechanisms of patination involving ORR were investigated by cyclic voltammetry, optical microscope, AFM, rotating disk electrode and other experimental methods: the occurrence of ORR cause the increase of local pH on electrode, and Cu2+ ions prefer to form Cu2O by reduction. Patina forms while Cu2O is oxidizing back to Cu2+.

<p>The functionalization of nonwoven electrospun polymeric fibers with metallic nanostructures has enabled the design of novel nanocomposite materials used in a wide range of applications. In particular, designs based on incorporating established antimicrobial species such as copper and silver have potential applications as antimicrobial filtration membranes, leveraging on the convoluted fiber assembly and high surface area–to–volume ratios of the constitutive fibers. Electroless deposition based on spontaneous electrochemical reactions offers a facile and tunable methodology for surface–confined growth of metallic nanostructures on the non–planar substrate architectures presented by nonwoven electrospun fibers. </p> <p>Firstly, this work explores, in a broad sense, the effects of two different seed catalyst chemistries, palladium and silver, on the evolution of copper nanoparticles on electrospun polyacrylonitrile fibers. Copper nanoparticle coverage and conformity; deposition kinetics; modifications in the surface chemistry of the PAN fibers; and thermal stability of the resultant nanocomposites were examined. Secondly, qualitative and quantitative assessment of the interfacial adhesion between the copper nanostructures and PAN fibers were undertaken by exploiting the elastic mismatch between both phases during tensile deformation. For copper nanocubes on nanofibers, the adhesion energy is estimated to be between 0.48 J/m² and 1.0 J/m² using strain and growth based adhesion models.</p> <p>Macroscopically, the compliant nature of the nonwoven fiber mats makes them susceptible to out-of-plane deformation during water filtration processes which may alter their size exclusion configuration for effective filtration. A bulge testing device is built and implemented to simulate and characterize hydraulic flow – induced deformation in the electrospun PAN fiber mats. The pressure–deflection relationships of the mats show a sub-linear dependence in contrast to classical continuum materials. The macroscopic mat behavior was governed by the properties of the constituent fibers, with an apparent mat bending rigidity dependent on the fiber diameters.</p> <p> Lastly, the nonwoven fiber mats functionalized with copper nanoparticles were evaluated for use as potential antimicrobial microfiltration membranes. The fiber mats displayed high water flux and high separation efficiency for model 3 μm particles, with separation factors reaching above 99%.</p>

<p>Materials prepared on the nanoscale often exhibit many different properties compared to the same materials in their bulk-state. Interest in nanostructured materials has increased because of these properties in fields such as microelectronics, catalysis, optics and sensors. This increased interest in nanostructured materials calls for new and more precise fabrication techniques.</p><p>This thesis describes how to use the porous anodic aluminium oxide as a template for the fabrication of a variety of nanostructured materials. Palladium and copper nanoparticles were deposited along the pore walls in anodic aluminum oxide using electroless deposition and atomic layer deposition. In both cases, it was possible to control the size of the nanoparticles by carefully monitoring the deposition parameters. The thesis also describes how Prussian blue nanoparticles and nanotubes can be fabricated using the anodic aluminium oxide as a template. The deposition of Prussian blue was performed by a sequential wet-chemical method. By using atomic layer deposition, it was also possible to deposit thin films of amorphous Nb2O5 on the pore walls. When the template was removed by etching, freestanding nanotubes were obtained. The anodic aluminium oxide membrane was also used as a mask for high energy (MeV) ion irradiation of an underlying substrate. The tracks produced were etched away with hydrogen fluoride. In this way, it was possible to transfer the highly ordered porous pattern from the mask onto other oxides such as SiO2 and TiO2.</p><p>All fabricated structures were characterized using a variety of analysis techniques: scanning electron microscopy for evaluating sample morphology; transmission electron microscopy for better resolved investigations of the morphology; X-ray diffraction to assess crystallinity; energy dispersive spectroscopy and X-ray fluorescence spectroscopy to determine the elemental composition and identify possible contaminants.</p><p>The general aim of the work described in this thesis has been to create a set of tools for use in the fabrication of a variety of nanostructured materials, whose dimensions composition can be tailored by selecting appropriate fabrication methods and parameters.</p>

Materials prepared on the nanoscale often exhibit many different properties compared to the same materials in their bulk-state. Interest in nanostructured materials has increased because of these properties in fields such as microelectronics, catalysis, optics and sensors. This increased interest in nanostructured materials calls for new and more precise fabrication techniques. This thesis describes how to use the porous anodic aluminium oxide as a template for the fabrication of a variety of nanostructured materials. Palladium and copper nanoparticles were deposited along the pore walls in anodic aluminum oxide using electroless deposition and atomic layer deposition. In both cases, it was possible to control the size of the nanoparticles by carefully monitoring the deposition parameters. The thesis also describes how Prussian blue nanoparticles and nanotubes can be fabricated using the anodic aluminium oxide as a template. The deposition of Prussian blue was performed by a sequential wet-chemical method. By using atomic layer deposition, it was also possible to deposit thin films of amorphous Nb2O5 on the pore walls. When the template was removed by etching, freestanding nanotubes were obtained. The anodic aluminium oxide membrane was also used as a mask for high energy (MeV) ion irradiation of an underlying substrate. The tracks produced were etched away with hydrogen fluoride. In this way, it was possible to transfer the highly ordered porous pattern from the mask onto other oxides such as SiO2 and TiO2. All fabricated structures were characterized using a variety of analysis techniques: scanning electron microscopy for evaluating sample morphology; transmission electron microscopy for better resolved investigations of the morphology; X-ray diffraction to assess crystallinity; energy dispersive spectroscopy and X-ray fluorescence spectroscopy to determine the elemental composition and identify possible contaminants. The general aim of the work described in this thesis has been to create a set of tools for use in the fabrication of a variety of nanostructured materials, whose dimensions composition can be tailored by selecting appropriate fabrication methods and parameters.

Cílem této diplomové práce jse najít nejnižší možnou tloušťku nikl-fosforového povlaku, který může být galvanicky pokoven mědí bez defektů na horčíkové slitině, nikl-fosforového nebo měděného povlaku. V teoretické části jsou shrnuty poznatky o hořčíkových slitinách a jejich korozi. Navíc se teoreticá část zaměřuje na popis procesu bezproudého niklování a elektrochemického pokovování mědí a jejich porovnání. Na konci teoretické části je shrnut současný výzkum o elektrochemickém pokovování hořčíkových slitin. V experimentální části byl popsán proces přípravy povlaků Ni-P a Cu na horčíkové slitině AZ91. Na jedné vrstvě a dvojité vrstvě Ni-P povlaku byla provedena elektrodepozice mědi. Navíc byl diskutován vliv předůpravy před samotnou elektrodepozicí mědi. Za účelem zjištění korozních vlastností vzorků byl vykonán potenciodynamický test. Následně byly připraveny metalografické výbrusy jednotlivých vzorků a pomocí světelného a rastrovacího elektronového mikroskopu byla provedena charakterizace. Na konec bylo zjištěno prvkové složení jednotlivých povlaků pomocí EDX analýzy.

Phase transformation behavior, micro structural development, mechanical and tribological properties of electroless Ni-B coating was characterized using different characterization techniques. As deposited electroless Ni-B coating containing 94 wt. % of NI and 6 wt. % of B is amorphous. It crystallizes via two exothermic reactions one at 3000C and another at 430˚C. It has been observed that there is also slow evolution of the heat in between this two exothermic reactions. XRD studies display that as deposited coating undergoes multi-stage crystallization events. At the first exothermic peak NI3B phases crystallizes, in between two a phase mixture of Ni and Ni3B and at the second exothermic peak NI2B + Ni3B crystallizes. Evolution of the free Ni in the complete crystalline coating is not predicted by the equilibrium phase diagram of the Ni-B system. Microscopic observation of the as deposited coating displays a novel compositionally modulated microstructure comprises of different length scales ranging from micrometer to nanometer level. In situ TEM study along with composition analysis were carried out in order to track the crystallization pathway and microstructural development. This kind of composition fluctuation of the coating is intrinsic to the deposition process. In best of our knowledge this kind of microstructure is the first time reported example of phase separation in a binary metal-metalloid system without spinoidal decomposition. Effect of this kind of microstructure and phase evolution on the mechanical and tribological properties of the coating is very profound. Increase in the nanocrystalline borides content of the coating increases the hardness value of the coating as well as improved tribological properties of the coating. In the low load regime (5 N and less) wear resistance of the coating is provided by the oxide layer formed on the wear track by preventing the direct contact between the coating and counterface. Local temperature rise due to friction and nancrystalline nature of the coating enhances the tendency of oxide layer formation. Characterization of the oxide layer was carried out using SEM, EPMA, Nanoindenation and Raman Spectroscopy. Whereas in case high load regime (above 5 N) this oxide layer breaks off and direct contact between the coating and counterface is established. This increases the wear rate of the coating. Material is removed from the coating through subsurface crack formation and propagation by low cycle fatigue mechanism. Effect of amorphous phase and free Ni on the tribological properties of the coating is detrimental by promoting a strong adhesion between the coating and steel counter face, whereas nanocrystalline borides shows opposite effect. A nano tribological studies using lateral force microscopy shows that nanocrystalline borides decreases the coefficient of friction of the coating. Phase evolution and microstructural characterization also shows that above 450˚C there is a significant diffusion of the boron from the coating to the steel substrate. This restrict the high temperature tribological studies of the coating up to a temperature range of 450˚C. Wear data along with worn track characterization demonstrate the fact that above 100˚C even in low load regime wear rate is very high. Wear of the coating is mainly governed by the plastic deformation of the coating and breakage of the protective oxide layer. Analytical calculation as well experimental observation shows that during the time of wear the temperature at the local contact region reaches a very high value even up to 1100˚C. This may soften the coating and causes the wear though plastic deformation of the coating.