The aim of this thesis was using surface-enhanced Raman scattering (SERS) microspectroscopy for the study of biomolecules and biological systems. The main probe molecule was cationic porphyrin H2TMPyP, however, other porphyrins, tryptophan and two lipids were also used. The sensitivity and reproducibility of several solid SERS substrates: (i) Au and Ag nanoparticles (NPs) immobilized via a bifunctional linker, (ii) AgNPs immobilized by drying, (iii) highly ordered Au and Ag film-over-nanosphere (FON) and (iv) Ag-coated insect wings were compared. On most of the solid substrates, the lowest detected H2TMPyP concentration was ~10-8 M. The highest sensitivity was provided by the dried drops of AgNPs/analyte mixture, where concentrations 1×10-10 M TMPyP, 1×10-5 M tryptophan, 2×10-7 M DSPC and 3×10-7 M DMTAP were detected. Nevertheless, the spectral reproducibility was decreased due to porphyrin metallation and perturbation of the lipid spectra in comparison to their Raman spectra from solution. The highest reproducibility was achieved by AuFON and Ag-coated insect wings. Finally, the AgNPs modified by PEG polymers were tested for intracellular application using HeLa cancer cells. Metallation of H2TMPyP served to probe the accessibility of PEG- AgNPs surface. The results proved that the accessibility...

Orientador: Oswaldo Luiz Alves / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-21T13:14:24Z (GMT). No. of bitstreams: 1 Paula_AmauriJardimde_D.pdf: 5147163 bytes, checksum: 5adb7ae3c081749f414b5e64e35a8135 (MD5) Previous issue date: 2012 / Resumo: Partindo-se do método de Stöber, um elegante e eficiente processo de síntese de partículas coloidais de SiO2, adaptações foram feitas para que fosse possível produzir nanopartículas porosas (50-80 nm) com alto valor de área de superfície (~1000 m g), volume de poros (~1,5 m g) e alta estabilidade coloidal. As nanoestruturas são compostas de nanopartículas coloidais de sílica hierarquicamente funcionalizadas, com poros internos com estrutura desordenada e diâmetros que vão de 1,8 a 10 nanômetros, funcionalizados com grupos fenil, e superfície externa recoberta com grupos propilmetilfosfonato ionizáveis. A funcionalização hierárquica e quimicamente antagônica (hidrofóbica = poros internos; hidrofílica = superfície externa) permite que moléculas hidrofóbicas (baixa solubilidade em água) sejam facilmente incorporadas nas cavidades porosas hidrofóbicas, ao passo que as partículas se mantêm de forma estável dispersas em água por meses. Moléculas hidrofóbicas foram incorporadas pelas nanopartículas porosas de SiO2 em concentração de até 3% (m/m) através da mistura de suspensões coloidais aquosas desses nanomateriais e as moléculas insolúveis (pós). A capacidade de incorporação da molécula hidrofóbica em questão (camptotecina) foi significantemente maior que outros sistemas porosos de SiO2 que estão sendo atualmente usados. A eficiência dos veículos moleculares foi comprovada através do carreamento da camptotecina, um potente agente antitumoral que levou à inibição do crescimento de células leucêmicas humanas. Além disso, as abordagens sintéticas usadas nessa Tese também possibilitaram a funcionalização da superfície externa das nanopartículas com outros grupos orgânicos hidrofílicos e reativos, como o propilamina. Consequentemente, as características dessas nanopartículas de SiO2 aqui mostradas preenchem uma série de demandas científicas atuais: a necessidade de nanoestruturas porosas de sílica com ampla distribuição de tamanho de poro, com morfologia homogênea, estreita distribuição de tamanhos e com real dispersibilidade em água (coloidais). Assim, o conjunto de propriedades apresentado abre perspectivas envolvendo o uso desse sistema como uma plataforma tecnológica suscetível a várias aplicações, servindo como um veículo para dispersão e liberação de moléculas hidrofóbicas em meio aquoso / Abstract: Based on the Stöber method, an elegant and efficient process for synthesizing SiO2 colloidal nanoparticles, modifications were done in order to produce porous nanoparticles (50-80 nm) with high surface area (~1000 mg), volume of pores (~1,5 m g) and high colloidal stability. The nanostructures are made of hierarchically functionalized colloidal silica nanoparticles, with internal pores with disordered structure and diameters ranging from 1.8 to 10 nanometers, functionalized with phenyl groups; and external surface covered with ionizable propylmethylphosphonate groups. The hierarchical and chemically antagonistic functionalization (hydrophobic = internal pores; hydrophilic = external surface) allows hydrophobic molecules (low solubility in water) to be easily incorporated in the hydrophobic porous cavities, whereas particles maintain stably dispersed in water for months. Hydrophobic molecules were incorporated by the porous SiO2 nanoparticles in concentrations up to 3% (w/w) simply by mixing colloidal aqueous suspensions of these nanomaterials and insoluble molecules (powders). The uptake capacity for a specific hydrophobic molecule (camptothecin) was significantly higher than in other porous systems of SiO2 that have been currently used. The efficiency of the molecular vehicles was evidenced through the transportation of camptothecin, a potent antitumoral agent which led to the growth inhibition of human leukemic cells. Besides, the synthetic approach used in this thesis also made possible the functionalization of the external surface of nanoparticles with other hydrophilic and reactive organic groups, such as propylamine. Consequently, the characteristics of these SiO2 nanoparticles here shown fulfill several current scientific demands: necessity of porous silica nanostructures with a wide distribution of pore sizes, homogeneous morphology, narrow size distribution and real dispersibility in water (colloidal). Thereby, this set of properties opens up perspectives involving the use of this system as a technological platform susceptible to several applications, acting as a vehicle for the dispersion and liberation of hydrophobic molecules in aqueous media / Doutorado / Quimica Inorganica / Doutor em Ciências

Controlling the size and size distribution of colloidal nanoparticles have gained extraordinary attention as their physical and chemical properties are strongly affected by size. Ligands are widely used to control the size and size distribution of nanoparticles; however, their exact roles in controlling the nanoparticle size distribution and the way they affect the nucleation and growth kinetics are poorly understood. Therefore, understanding the nucleation and growth mechanisms and developing theoretical/modeling framework will pave the way towards controlled synthesis of colloidal nanoparticles with desired sizes and polydispersity. This dissertation focuses on identifying the possible roles of ligands and size on the kinetics of nanoparticle formation and growth using in-situ characterization tools such as small-angle X-ray scattering (SAXS) and kinetic modeling. The presented work further focuses on developing kinetic models to capture the main nucleation and growth reactions and examines how ligand-metal interactions could potentially alter the rate of nucleation and growth rates, and consequently the nanoparticle size distribution. Additionally, this work highlights the importance of using multi-observables including the concentration of nanoparticles, size and/or precursor consumption, and polydispersity to differentiate between different nucleation and growth models and extract accurate information on the rates of nanoparticle nucleation and growth. Specifically, during the formation and growth of colloidal nanoparticles, complex reactions are occurring and as such nucleation and growth can take place through various reaction pathways. Therefore, sensitivity analysis was applied to effectively compare different nucleation and growth models and identify the most important reactions and obtain a reduced model (e.g. a minimalistic model) required for efficient data analysis. In the following chapters, a more sophisticated modeling approach is presented (population balance model) capable of capturing the average-properties of nanoparticle size distribution. PBM allows us to predict the growth rate of nanoparticles of different sizes, the ligand surface coverage for each individual size, and the parameters involved in altering the size distribution. Additionally, thermodynamic calculations of nanoparticle growth and ligand-metal binding as a function of size and ligand surface coverage were conducted to further shed light on the kinetics of nanoparticle formation and growth. The combination of kinetic modeling, in-situ SAXS and thermodynamic calculations can significantly advance the understanding of nucleation and growth mechanisms and guide toward controlling size and polydispersity. / Doctor of Philosophy / The synthesis of colloidal metal nanoparticles with superior control over size and size distribution, and has attracted much attention given the wide applications of these nanomaterials in the fields of catalysis, photonics, and electronics. Obtaining nanoparticles with desired sizes and polydispersity is vital for enhancing the consistency and performance for specific applications (e.g., catalytic converters for automotive emission). Ligands are often employed to prevent agglomeration and also control the nanoparticle size and size distribution. Ligands can affect the precursor reactivity and therefore the reduction/nucleation by binding with the metal precursor. Nucleation refers to the assimilation of few atoms to form initial nuclei acting as templates for nanoparticle growth. Additionally, ligands can bind with the nanoparticle surface sites and change the rate of surface growth and therefore the final nanoparticle size. Despite strong effects of ligands in the colloidal nanoparticle synthesis, their exact role in the nucleation and growth kinetics is yet to be identified. Additionally, nucleation and growth models capable of unraveling the underlying mechanisms of nucleation and growth in the presence of ligands are still lacking in the literature. Therefore, obtaining nanoparticles with desired sizes and polydispersity mostly relies on trial-and-error approach making the synthesis costly and inefficient. As such, developing models capable of predicting suitable synthesis conditions is contingent upon understanding the chemistry and mechanism involved during nanoparticles formation. Therefore, in this study, novel kinetic models were developed to capture the nucleation and growth kinetics of colloidal metal nanoparticles under different synthetic conditions (different types of solvents, different concentrations of ligand and metal). In-situ SAXS was further employed to measure the average diameter, concentration of nanoparticles, and polydispersity during the synthesis and extract the nucleation and growth rates (evolution of concentration of nanoparticles and size). First, an average-property model was developed to account for ligand-metal bindings and capture the size and concentration of nanoparticles during the synthesis. Then, a more complex modeling approach; PBM, accompanied by the thermodynamic calculations of surface growth and ligand-nanoparticle binding enthalpies was implemented to capture the size distribution. As it will be shown later, the determination of the underlying mechanisms resulted in a highly predictive kinetic model capable of predicting the synthetic conditions to obtain nanoparticles with desired sizes. The proposed methodology can serve as a powerful tool to synthesize nanoparticles with specific sizes and polydispersity.

This thesis deals with the study of GaAs surface properties and with methodology of metal (mainly gold) nanoparticles deposition on GaAs substrate. GaAs has complicated surface oxides structure, which are very reactive when exposed to various chemicals (both acids and alkalines) and therefore they change GaAs surface properties. That is why the study of this properties is crucial for understanding of GaAs surface reactions on metal particles colloidal solution, from which the nanoparticles are deposited on the surface. The possibilites of GaAs surface etching and passivation are discussed. These should lead to surface stability enhancement during colloidal nanoparticles deposition. There was also studied the influence of adhesive polymer monolayer grown on GaAs substrate to the amount of nanoparticles deposited to the surface after substrate immersion into colloidal solution. This thesis concentrates on analyzing of methods, how the gold colloidal nanoparticles can be deposited selectivelly, only to defined areas. The areas were defined using charged particle beam.

L’assemblage dirigé de nanoparticules colloïdales sur des surfaces est une étape clé pour l’étude et la caractérisation de leurs propriétés physiques, ainsi que pour l’élaboration de dispositifs fonctionnels les intégrant. Ces travaux de thèse portent sur le développement et l’utilisation d’une technique d’assemblage dirigé rapide, applicable à une large gamme de dispersions colloïdales : la nanoxérographie par microscopie à force atomique (AFM). Le protocole de nanoxérographie par AFM est composé de deux étapes : (i) l’injection de motifs de charges dans un matériau électret, suivie (ii) d’un développement dans une dispersion colloïdale permettant de piéger les nanoparticules en quelques secondes seulement sur les motifs de charges par interaction électrostatique. L’ajustement précis des différents leviers expérimentaux et l’utilisation de dispersions colloïdales synthétisées par voie chimique avec des caractéristiques finement contrôlées nous ont permis d’affiner notre compréhension des mécanismes régissant l’assemblage dirigé par nanoxérographie par AFM et de repousser les limites de cette technique sur trois points précis : les assemblages binaires, l’assemblage de nano-objets individuels et les assemblages multi-couches de nano-objets. Les résultats obtenus ont ensuite été mis à profit pour élaborer des étiquettes de marquage sécurisées micrométriques à base de nanocristaux luminescents de NaYF4 dopés avec des terres rares destinées à la lutte anti-contrefaçon et le traçage de produits. / Directed assembly of colloidal nanoparticles is a fundamental step for observation and quantitative measurement of their physical properties, as well as using them for the conception and manufacturing of innovative functional devices. This research aim to enhance a technique used for fast directed assembly of a wide range of colloidal nanoparticles : atomic force microscopy (AFM) nanoxerography. This technique consists of two steps : (i) injection of charge patterns written on a thin layer of electret, followed by (ii) an immersion of the electret into the colloidal solution. This last step allows nearly instantaneous selective deposition of nanoparticles onto the charge patterns. Fine tuning of few experimental levers and chemical synthesis of customized nanoparticles solution with finely tuned physical properties has allowed us to further our understanding of the assembly obtained with AFM nanoxerography mechanics. Three previously known limitations of the technique have been lifted : binary assembly, single nanoparticle assembly and multilayered assembly. Results obtained have then been used to design and produce microtags out of rare-earth based photo-luminescent NaYF4 nanocrystals, with tremendous potential for product traceability and fight against counterfeiting.

Un grand défi actuel consiste à réaliser des capteurs innovants tirant partie des propriétés singulières de nanoparticules colloïdales synthétisées par voie chimique et assemblées de manière contrôlée sur des surfaces. L’objet de cette thèse est le développement de jauges de contrainte résistives à base de nanoparticules. Ces jauges de contrainte sont constituées de lignes parallèles, de quelques micromètres de large, denses, de nanoparticules colloïdales d’or synthétisées par voie chimique et assemblées sur des substrats souples par assemblage convectif contrôlé. Le principe de ces capteurs résistifs repose sur la conduction tunnel entre les nanoparticules qui varie de manière exponentielle lorsque que l’assemblée est déformée. Des mesures électro-mécaniques couplées à des observations en microscopie électronique à balayage et à force atomique ont permis d’identifier, de quantifier et de comprendre l’impact de la taille et de la nature des ligands des nanoparticules sur la sensibilité et les phénomènes de dérive de la résistance à vide des jauges de contrainte. Ces travaux, associés à des mesures de diffusion de rayons X aux petits angles ont permis de corréler les variations macroscopiques de résistance électrique des jauges de contrainte aux déplacements relatifs des nanoparticules. Finalement, ces jauges de contrainte ultra-sensibles et miniatures, mises en matrices, ont été exploitées pour réaliser des surfaces tactiles souples multi-points et sensibles à l’intensité de l’appui / One recent big challenge is to implement innovative sensors that take advantage of the unique properties of colloidal nanoparticles chemically synthesized and assembled on various surfaces. The goal of this work is the development of nanoparticle based resistive strain gauges. These strain gauges are constructed of few micrometers wide parallel wires of close packed colloidal gold nanoparticles, chemically synthesized, and assembled on flexible substrates by convective self assembly. The principle of these resistive sensors is based on the tunnel conduction between the adjacent nanoparticles which varies exponentially as the assembly is stretched. Electro-mechanical measurements coupled with scanning electron microscopy and atomic force microscopy observations were used to identify, quantify and understand the impact of the nanoparticle size and the nature of the protecting ligands, on the gauge sensitivity and the drift of the resistance at rest of the nanoparticle based strain gauges. Coupled with small angle x-ray scattering measurements, these studies allowed us to correlate the macroscopic changes in electrical resistance of the strain gauges to the relative displacement of the nanoparticles at the nanoscale. Finally, a matrix of these miniature ultra-sensitive gauges was used to construct flexible touch screen panels capable of measuring the intensity of several touches simultaneously

<div>Metal-zeolites are promising materials for passive adsorber technologies for the abatement of nitrogen oxides (NOx, x = 1,2) and aldehydes during low-temperature operation in automotive exhaust aftertreatment systems. The aqueous-phase exchange processes used commonly to prepare metal-zeolites typically require mononuclear, transition metal complexes to diffuse within intrazeolite pore networks with their solvation shells and replace extra framework cations of higher chemical potential. When metal complexes are larger than the zeolite pore-limiting diameter, this imposes intracrystalline transport restrictions; thus, complexes and agglomerates tend to preferentially deposit near the surfaces of crystallites, requiring post-synthetic treatments to disperse metal species more uniformly throughout zeolite crystallites via solid-state ion-exchange processes. Here, we address the influence of post-synthetic gas treatments and zeolite material properties on the structural interconversion and exchange of extra framework Pd in CHA zeolites with a focus on the thermodynamic, kinetic, and mechanistic factors that dictate the Pd site structures and spatial distributions that form.<br></div><div><br></div><div>Pd-amine complexes introduced via incipient wetness impregnation on CHA zeolites were found to preferentially site near crystallite surfaces. Post-synthetic treatments in flowing air results in Pd-amine decomposition and agglomeration to metallic Pd0and supersequent oxidation to PdO, before converting to mononuclear Pd²⁺cations through an Ostwald ripening mechanism at high temperatures (>550 K). Progressively higher air treatment temperatures (up to 1023 K) were found to (1) thermodynamically favor the formation of mononu-clear Pd²⁺cations relative to agglomerated PdO particles, (2) increase the apparent rate of structural interconversion to mononuclear Pd²⁺, and (3) facilitate longer-range mobility of molecular intermediates involved in Ostwald ripening processes that allow Pd cations to form deeper within zeolite crystallites to form more uniformly dispersed Pd-zeolite materials. Additionally, the controlled synthetic variation of the atomic arrangement of 1 or 2Al sites in the 6-membered ring of CHA was used to show a thermodynamic preference to form mononuclear Pd2+cations charge-compensated by 2 Al sites over [PdOH]⁺complexes at 1 Al site. Colloidal Pd nanoparticle syntheses and deposition methods were used to prepare monodisperse Pd-CHA materials to isolate the effects of Pd particle size on structuralinterconversion to mononuclear Pd²⁺under a range of external environments. Consistent with computational thermodynamic predictions, smaller Pd particle sizes favor structural interconversion to mononuclear Pd²⁺under high-temperature air treatments (598–973 K),while adding H2O to the air stream inhibits the thermodynamics but not the kinetics of mononuclear Pd²⁺formation, demonstrating that water vapor in exhaust streams may be deleterious to the long-term stability of Pd-zeolite materials for passive NOx adsorption.<br></div><div><br></div><div>The influence of metal-zeolite material properties on the adsorption, desorption, and conversion of formaldehyde, a government-regulated automotive pollutant, under realistic conditions was investigated to identify beneficial material properties for this emerging application in mobile engine pollution abatement. A suite of Beta zeolite materials was synthesized with varied adsorption site identity (Brønsted acid, Lewis acid, silanol groups, and extra framework metal oxide) and bulk site densities. All materials stored formaldehyde and converted a large fraction of formaldehyde to more environmentally benign CO and CO₂, demonstrating the efficacy of silanol defects and zeolitic supports for the storage of formaldehyde. Sn-containing zeotypes, containing either Lewis acidic framework Sn sites or extra framework SnO_x particles, resulted in the greatest selectivity to CO and CO₂ formed during formaldehyde desorption, suggests that Sn species are a beneficial component in metal-zeolite formulations for the abatement of formaldehyde in automotive exhaust streams.<br></div><div><br></div><div>This work demonstrates how combining precise synthesis of metal-zeolites of varied bulk and atomic properties with site-specific characterization and titration methods enables systematically disentangling the influence of separate material properties (e.g., Pd particle size, zeolite framework Al arrangement, silanol density, heteroatom identify) and external environment on changes to metal structure, speciation, and oxidation state. This approach provides thermodynamic, kinetic, and mechanistic insights into the factors that influence metal re-structuring under the practical conditions encountered in automotive exhaust after treatment applications and guidance for materials design and treatment strategies to form desired metal structures during synthesis and after regeneration protocols.<br></div>

Grâce à leurs propriétés physiques/chimiques uniques, les nanoparticules colloïdales sont au cœur de nombreuses applications innovantes. Afin de faciliter leur caractérisation ou de les intégrer dans des dispositifs fonctionnels, il est nécessaire de les assembler de manière dirigée sur des surfaces solides. Dans ce contexte, l’objectif de cette thèse est de mieux comprendre et d’optimiser la technique de nanoxérographie, méthode d’assemblage dirigé où des nanoparticules sont piégées sur des motifs de charges électrostatiques. Après un premier travail consistant à améliorer le procédé de nanoxérographie, trois problématiques spécifiques ont été adressées : (i) l’assemblage de particules micrométriques. Le couplage de simulations numériques et de manipulations expérimentales a permis d’identifier les paramètres clés de l’assemblage de telles particules colloïdales et d’élargir (facteur 100) la gamme de tailles de particules assemblables par nanoxérographie. (ii) l’analyse de l’assemblage multicouche. Par le biais de nanoparticules modèles luminescentes et par la mise en place d’un nouveau protocole d’assemblage, les critères clés génériques pour l’assemblage 3D de colloïdes par nanoxérographie ont été dégagés. (ii) l’assemblage dirigé de nanogels sensibles à un stimulus environnemental extérieur. L’utilisation d’un protocole d’assemblage optimisé a permis d’élaborer des assemblages de nanogels interactifs avec leur environnement et du faire du tri sélectif de ces nanoparticules sur une même surface. / Owing to their unique physico-chemical properties, colloidal nanoparticles are building blocks for the creation of plentiful innovative devices. In order to make easier their characterization and to incorporate them into functional nano-devices, it is necessary to perfectly control their directed assemblies onto solid surfaces. In this context, this thesis’ purpose is to simultaneously better understand and optimize the nanoxerography method, which allows electrostatic and selective directing assemblies of nanoparticles onto charged patterns. After an optimization of the nanoxerography process, three specific problematics have been addressed: (1) micron-sized particles assembly. The combined use of numerical simulations and experiments enabled to unveil the key parameters involved in micron-sized particles assembly and to expend the particle size range foreseeable for an assembly by nanoxerography (factor 100). (2) the 3D assembly analysis. The influence of diverse parameters on the 3D assembly of luminescent model nanoparticles was quantified by using a new assembly protocol. The results gave the generic key criterions for the 3D assembly of colloids by nanoxerography. (3) directed assembly of nanogels sensitive to an external environmental stimulus. The use of an optimized protocol allowed elaborating nanogels assemblies interactive with their environment and to sort these nanoparticles onto the same surface.

Planetary ball milling (PBM) is a well-known technique for efficient size reduction and homogenization of materials that has been used for many decades in various engineering and industrial processes. More recently, it has emerged as a unique top-down nanofabrication approach for nanomaterials based on nanoscale grinding. However, its potential application in nanostructured thin film fabrication has not been fully explored, as only a limited number of studies have been carried out. In this work, the effects of different grinding parameters (speed, time and solvents) were used to create previously unstudied nanoscale grinding conditions for nanostructured thin film materials via PBM with distinct and novel properties: Nanoparticles of silicon, titanium disilicide (TiSi2) and zinc oxide (ZnO) ground in different solvents (deionized (DI) water/ ethylene glycol (EG)/isopropyl alcohol) resulted in colloidal suspensions (or nanoinks) that could be used to coat various substrates (wafers, glass, flexible substrates, etc.) via drop casting, doctor blading or dip coating. Thin film properties such as wettability, electrical conductivity and gas sensing behavior are studied. The fabricated thin film coating properties could be tuned depending on the combination of starting powder materials, grinding parameters and resulting nanoparticle size/geometry: The influence of surface chemistry, solvent type, particle geometry, surface roughness and defects was shown to alter the conductivity and surface wettability of the resultant films. Thus, thin films formed using PBM nanoinks allow varied and tunable properties for advanced multi-functional coatings and devices. To demonstrate the feasibility of PBM nanoinks for thin film device applications, ZnO nanoinks were used to create chemiresistive gas sensors that operate at room temperature. By varying grinding parameters (speed, time and solvent) thin film sensors with differing particle sizes and porosity were produced and tested with air/oxygen against hydrogen, argon and methane target gas species, in addition to relative humidity. Grinding speeds of up to 1000 rpm produced particle sizes and RMS thin film roughness below 100 nm, as measured by atomic force microscopy and scanning electron microscopy. Raman spectroscopy, photoluminescence and x-ray analysis confirmed the purity and structure of resulting films. The peak gas sensor response was found for grinding parameters of 400 rpm (average particle size 275 nm) and 30 minutes (average particle size 225 nm) in EG and DI water, respectively, which could be correlated to an increased film porosity and an enhanced electron concentration resulting from adsorption/desorption of oxygen ions on the surface of ZnO nanoparticles. Similarly, gas response and dynamic behavior were found to improve as the operating temperature was increased between 100 and 150 °C. These results demonstrate the use of low-cost PBM nanoinks to optimize the active materials for solution-processed thin film gas/humidity sensors that can operate at room temperature for use in environmental, medical, food packaging, laboratory, and industrial applications. Overall, the nanogrinding technique can produce large amounts of nanoparticle suspension with variable particle sizes for creating thin films with tunable properties. By adjusting grinding parameters, the nanoparticle shape/size and properties can be varied resulting in nanoparticle inks for inexpensive coatings on various substrates and for use in different applications. / Graduate