Dissertations / Theses on the topic 'Ag nanoparticles films'

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The fabrics are used for various applications in our daily life, and particularly natural fabrics such as cotton are susceptible to bacterial growth due to moisture that it can accumulate which facilitates this process and also the fibers themselves may serve as nutrients for the growth of microorganisms. In this work, the synthesis of silver and zinc oxide particles was carried out for their and corporation into cotton fibers by the Layer-by-layer method. The silver nanoparticles provide high biocidal activity when incorporated into fabrics textiles and zinc oxide particles promote a block against ultraviolet radiation and also provide the self-cleaning properties for the fabric by the oxidation of compounds on its surface. Therefore the aim of this work was to promote these characteristics in a cotton fabric. The synthesis of silver nanoparticles and zinc oxide were performed using polyelectrolytes as suspension stabilizers. The syntheses were carried out using four ratios related to the metal concentration and polyelectrolyte (1, 2, 5 and 10%). For silver nanoparticles, the 3-n-propylpyridinium silsesquioxane chloride (SiPy+Cl-) was used as stabilizer obtaining nanoparticles of 5 nm in diameter and for ZnO nanoparticles it was used the poly(dialildimethylamonium chloride) PDDA, obtaining in this case particles with sizes larger than 400 nm. These nanocomposites were used to obtain a thin coating on the cotton fibers. For the construction of the films on the cotton fibers, it was used the LbL technique, where it was necessary to perform a prior chemical treatment on the fabric in order to provide an interaction between the cotton fabric surface and the polyelectrolytes. The bilayers were grown in fabrics with the use of polystyrenesulfonate (PSS) as polyanion. Characterization of the fabrics coated with Ag/SiPy+Cl- nanocomposites was performed by varying the number of bilayers. From the SEM images, it was observed the LbL coating on the fabric surface and EDS analysis enabled to estimate the amount of AgNps adsorbed on fabrics. The antibacterial tests for these fabrics showed good results for E. coli and S. aureus bacteria indicating a bactericidal and bacteriostatic character. From the color analysis and UV- Vis spectra of cotton fabrics, it was possible to estimate its homogeneity. Studies of the release of silver nanoparticles were performed by atomic absorption analysis of the washing solution up to 15 washing cycles of the fabric, indicating a high stability of the nanocomposite coating. SEM characterization of the fabrics coated with the nanocomposite ZnO/PDDA showed the growth of the bilayers as well as increase of the ZnO amount on the cotton fiber by the EDS analysis. Through TEM images observed nanoparticles with sizes between 2-10 nm. The analysis of the UV protection factor of these fabrics showed a 60% blockage of UVA and UVB radiations. Studies of photocatalytic degradation of methylene blue dye showed good results degradando totalmente o corante em 8 horas para tecidos revestidos com poucas bicamadas, which increased with the number of bilayers in the fabric. It was observed that in presence of silver nanoparticles, the degradation of the dye becomes more pronounced. The analysis of the shedding of particles of zinc oxide was also performed by atomic absorption analysis of the wash solution until 15 washing cycles. The results for this nanocomposite coated on the fabric also showed satisfactory results.
Os tecidos são utilizados para várias aplicações em nosso dia a dia, e principalmente os tecidos naturais como o algodão são suscetíveis ao crescimento bacteriano devido ao fato de acumularem umidade o que facilita esse processo, além das próprias fibras servirem como nutrientes para o crescimento de microorganismos. Neste trabalho foi realizada a síntese de nanopartículas de prata e óxido de zinco para incorporação em fibras de algodão através do método Layer-by-layer. As nanopartículas de prata conferem alta atividade biocida quando incorporada em tecidos e as nanopartículas de óxido de zinco promovem um bloqueio contra radiação ultra-violeta e também pode tornar o tecido auto limpante através da oxidação de compostos na sua superfície. Portanto o objetivo deste trabalho foi promover essas características em um tecido de algodão. A síntese das nanopartículas de prata e óxido de zinco foram realizadas utilizando-se polieletrólitos como estabilizantes da suspensão. As sínteses foram realizadas em 4 proporções (1, 2, 5 e 10%) do metal em relação a concentração do polieletrólito. Para as nanopartículas de prata utilizou-se o cloreto de 3-n-propilpiridínio silsesquioxano (SiPy+Cl-) como estabilizante obtendo-se nanopartículas de 5 nm de diâmetro enquanto que para o ZnO utilizou-se o Poli(cloreto de dialildimetilamônio) PDDA, obtendo-se neste caso nanopartículas com tamanhos maiores que 400 nm. Esses nanocompósitos foram utilizados para realizar um revestimento sobre fibras de algodão. Para isto utilizou-se a técnica LbL, onde se foi necessário realizar um tratamento químico prévio no tecido para haver uma interação entre a superfície do tecido e os polieletrólitos. As bicamadas foram crescidas no tecido com a utilização do poliestireno sulfonado (PSS) como poliânion. A caracterização dos tecidos revestidos com os nanocompósitos Ag/SiPy+Cl- foi realizada variando-se o número de bicamadas. A partir de imagens de MEV observou-se o revestimento crescido sobre a superfície do tecido e a análise de EDS foi utilizada como tentativa de estimar a quantidade de prata adsorvida nos tecidos. Através de imagens de TEM observou-se nanopartículas com tamanhos entre 2 – 10 nm. Os testes antibacterianos para estes tecidos apresentaram bons resultados para as bactérias E. coli e S. aureus indicando um caráter bactericida e bacteriostático. Também realizou-se a análise de cor através do método CieLab e espectros UV-Vis dos tecidos para estimar a sua homogeneidade. A análise de desprendimento de partículas de prata foi realizada através da análise de absorção atômica da solução de lavagem até um ciclo de 15 lavagens do tecido, resultado que indicou uma alta estabilidade do nanocompósito revestido sobre o tecido. A caracterização dos tecidos revestidos com o nanocompósito ZnO/PDDA foi realizada através das imagens de MEV, onde observou-se o crescimento das bicamadas bem como o aumento da quantidade de ZnO nos tecidos visto pela análise de EDS. A análise do fator de proteção UV destes tecidos apresentou um resultado de até 60% do bloqueio das radiações UVA e UVB. Os testes de degradação fotocatalítica do corante azul de metileno apresentaram bons resultados degradando totalmente o corante em 8 horas para tecidos revestidos com poucas bicamadas, aumentando esse efeito à medida que aumentou-se o número de bicamadas no tecido e na presença de nanopartículas de prata a degradação do corante apresentou-se mais acentuada. A análise de desprendimento de partículas de zinco também foi realizada através da análise de absorção atômica da solução de lavagem até um ciclo de 15 lavagens do tecido, o resultado para este nanocompósito revestido sobre o tecido também apresentou resultados satisfatórios.

Les nanoparticules (NPs) d'Ag sont très utilisées dans le secteur de la santé, dans l'industrie alimentaire et dans les produits de consommation pour leurs propriétés antimicrobiennes. Le grand rapport surface sur volume des NPs d'Ag permet une augmentation importante du relargage d'Ag comparé au matériau massif et donc une toxicité accrue vis à vis des micro-organismes sensibles à cet élément. Ce travail de thèse présente une évaluation des propriétés antimicrobiennes de petites NPs d'Ag (<20 nm) enrobées dans des matrices de silice sur la photosynthèse d'algues vertes. Deux techniques d'élaboration par voie physique ont été utilisées pour fabriquer ces nanocomposites: (i) l'implantation ionique à basse énergie et (ii) la pulvérisation d'Ag couplée avec la polymérisation plasma. Les propriétés structurales et optiques de ces nanostructures ont été étudiées par microscopie électronique à transmission, réflectivité et ellipsométrie. Cette dernière technique, couplée à un modèle basé sur l'approximation quasi-statique de type Maxwell-Garnett, a permis la détection de petites variations dans la taille et la densité des NPs d'Ag. Le relargage d'argent de ces NPs d'Ag enrobées dans des diélectriques a été mesuré par spectrométrie de masse après immersion dans de l'eau tamponnée. La toxicité à court terme de l'Ag sur la photosynthèse d'algues vertes, Chlamydomonas reinhardtii, a été évaluée par fluorométrie. L'enrobage des nanoparticules dans un diélectrique réduit leur interaction avec l'environnement, et les protège d'une oxydation rapide. La libération d'Ag bio-disponible (impactant sur la photosynthèse des algues) est contrôlée par la profondeur à laquelle se trouvent les NPs d'Ag dans la matrice hôte de silice. Cette étude permet d'envisager le design de revêtements à effet biocide contrôlé. En couplant les propriétés antimicrobiennes de ces NPs d'Ag enrobées à leur qualité d'antenne plasmonique, ces nanocomposites peuvent être utilisés pour détecter et prévenir les premières étapes de la formation de biofilms sur des surfaces. Ainsi, une dernière partie de ce travail est dédiée à l'étude de la stabilité et de l'adsorption de protéines fluorescentes Discosoma rouges recombinantes (DsRed) sur ces surfaces diélectriques avec la perspective du développement de dispositifs SERS
Silver nanoparticles (AgNPs) because of their strong biocide activity are widely used in health-care sector, food industry and various consumer products. Their huge surface-volume ratio enhances the silver release compared to the bulk material, leading to an increased toxicity for microorganisms sensitive to this element. This work presents an assessment of the biocide properties on algal photosynthesis of small (<20 nm) AgNPs embedded in silica layers. Two physical approaches were used to elaborate these nanocomposites: (i) low energy ion beam synthesis and (ii) combined silver sputtering and plasma polymerization. These techniques allow elaboration of a single layer of AgNPs embedded in silica films at defined nanometer distances (from 0 to 7 nm) beneath the free surface. The structural and optical properties of the nanocomposites were studied by transmission electron microscopy, reflectance spectroscopy and ellipsometry. This last technique, coupled to modelling based on the quasi-static approximation of the classical Maxwell-Garnett formalism, allowed detection of small variations over the size and density of the embedded AgNPs. The silver release from the nanostructures after immersion in buffered water was measured by inductively coupled plasma mass spectrometry. The short-term toxicity of Ag to the photosynthesis of green algae, Chlamydomonas reinhardtii, was assessed by fluorometry. Embedding AgNPs reduces their interactions with the buffered water, protecting the AgNPs from fast oxidation. The release of bio-available silver (impacting on the algal photosynthesis) is controlled by the depth at which AgNPs are located for the given host silica matrix. This provides a procedure to tailor the biocide effect of nanocomposites containing AgNPs. By coupling the controlled antimicrobial properties of the embedded AgNPs and their quality as plasmonic antenna, these coatings can be used to detect and prevent the first stages of biofilm formation. Hence, the last part of this work is dedicated to a study of the structural stability and adsorption properties of Discosoma recombinant red (DsRed) fluorescent proteins deposited on these dielectric surfaces with perspectives of development of SERS devices

L'essor des procédés de micro et nano-fabrications rend aujourd'hui accessible la synthèse contrôlée de nanoparticules métalliques (typiquement de 3 à 200nm) offrant de larges résonances d'absorption et de diffusion dont les fréquences peuvent être contrôlées finement en variant judicieusement leur géométrie et leur composition. Dans ce travail de thèse relevant de l'électrodynamique classique établit par Maxwell, nous étudions numériquement l'intérêt de ces particules pour la problématique du (dé)couplage de la lumière piégée dans un film mince diélectrique - une géométrie de référence permettant de rendre compte du phénomène de piégeage qui limite considérablement l'efficacité de dispositifs électroluminescents et de certaines cellules solaires. Pour ce faire, nous proposons quelques règles de conception de nanoparticules capables d'extraire efficacement la lumière piégée. Pour un émetteur seul, environ 20% de la lumière émise est rayonnée hors du guide (rad~0.2). L'ajout d'une monocouche (~50nm d'épaisseur) composée d'un ensemble de particules " optimisées " et aléatoirement positionnées autour de l'émetteur permet d'accroître cette efficacité jusqu'à 70% en moyenne statistique sur le désordre. D'intéressants effets de cohérences liés à la nature du désordre au sein de ladite couche sont également mis en évidence.

Among silver-containing chalcogenides Ag-As-S ternary system are take the remarkable place. Glasses and composites of Ag–As–S system are promising materials for creation of solid electrolytes, electrochemical sensors, electrochromic displays etc. In the recent years surface plasmon resonance has been used to enhance photostructural changes due to the laser light. Therefore, it was of a certain interest to obtain and examine such effects in the new investigated Ag-As-S thin films.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
Materiais nanoestruturados como nanocristais semicondutores de telureto de cádmio (QDs de CdTe) e nanopartículas metálicas de prata (NPsAg) têm sido utilizados como nanosondas analíticas, explorando suas propriedades de luminescência e de ressonância de superfície plasmônica localizada (LSPR), respectivamente, sejam em dispersão coloidal ou em filmes finos. Em função das suas configurações experimentais, sistemas microfluídicos podem ser utilizados tanto para síntese de materiais nanoestruturados quanto para análise de analitos de interesses biológicos. No presente estudo, QDs-CdTe encapados com ácido tioglicólico (TGA) foram sintetizados em batelada e em regime de fluxo contínuo a partir da injeção dos precursores de cádmio e telúrio por bombas-seringas para um sistema de tubos de aço passando por fornos tubulares horizontais com controladores de temperatura (110-140 graus Celsius). Para otimizar os parâmetros experimentais foram variados a taxa de vazão volumétrica (0,15 - 0,03 mL min(-1)) e a razão molar de Cd:Te (1:0,3 - 1:1,5). Os resultados demonstraram que o efeito da razão molar na síntese de QDs apresentou ser mais significativo em comparação à variação da temperatura, obtendo QDs com FWHM de 64 – 86 nm. Filmes luminescentes poliméricos de PVA e PDMS foram desenvolvidos pelas técnicas de impregnação, mistura de QDs na matriz polimérica e por spin coating. Pela técnica de spin coating foram produzidos filmes de 58,7 nm. Filmes de QDs sobre substrato de vidro foram obtidos pelo processo de silanização da superfície do vidro. Todos os filmes apresentaram instabilidade de luminescência ao longo do tempo. Dispersões coloidais de NPsAg revestidas com ligantes orgânicos citrato e tartarato, nas razões Ag+:ligante (1:1 e 1:0,5), foram sintetizadas a partir da injeção dos ligantes e nitrato de prata por bombas-seringas em um microrreator tubular polimérico. As NPsAg-citrato e NPsAg-tartarato apresentaram cargas superficiais negativas e tamanhos médios de 12,5 nm. As bandas LSPR foram observadas para monitorar a interação entre as nanosonda de prata e os fármacos aminoglicosidico em fluxo contínuo mediante um fotômetro acoplado a uma cela de fluxo. Nas concentrações iguais ou maior que 2 × 10(-7) mol L(-1), produziu uma mudança no perfil espectral da nanosonda de NPsAg, com o decaimento do sinal no comprimento de onda 404 nm e o surgimento de uma nova banda em 480 nm, resultante da aglomeração das nanopartículas. Além disso, as NPsAg-tartarato foram depositadas sobre substrato de vidro para realização de filmes fino com objetivo de desenvolver, em parceria com a Universidade Federal de Pernambuco (UFPE), um biosensor baseado na ressonância plasmônica localizada (LSPR) para determinação do antígeno Candida albicans.
Nanostructured materials such as cadmium telluride semiconductor nanocrystals (QDs-CdTe) and silver nanoparticles (NPsAg) have been used as analytical nanoprobes, exploiting their luminescence properties and localized plasmonic surface resonance (LSPR), respectively, both in colloidal suspension or on thin solid films. Due to their experimental set-up, microfluidic systems can be used, both, for synthesis of nanostructured materials and for the analytic detection of biological and pharmaceutical compounds. In the present study, thioglycolic acid (TGA) coated QDs-CdTe were synthesized in batch and in a continuous flow regime from the injection of cadmium and tellurium precursors by syringe pumps into a steel tubes through horizontal tubular furnaces with temperature controllers (110 - 140 Celsius degrees). To optimize the experimental conditions, we modulate the volumetric flow rate (0.15 - 0.03 mL min(-1)) and the Cd:Te molar ratio (1:0.3 - 1:1.5). The results showed that the effect of the molar ratio on the synthesis of QDs was more significant compared to the temperature variation, obtaining QDs with FWHM of 64 - 86 nm. Polimeric luminescent films with PDMS e PVA were developed with impregnation, mixing QDs-TGA in PDMS and PVA and spin coating techniques. By the spin coating technique we produced luminescent film of 58.7 nm thickness. QDs-TGA film on glass substrate were obtained by means of surface silanization.All the film showed luminescence instability over time. Colloidal dispersions of NPsAg coated with the organic citrate and tartrate ligands in the Ag+/ligand ratios (1:1 and 1:0.5) were synthesized from the injection of organic ligands and silver nitrate by syringe pumps into a polymeric tubular micro-reactor. NPsAg-citrate and NPsAg-tartrate presented negative surface charges and average sizes of 12.5. The SPR band was monitored to follow the interation between the silver nanoprobe with kanamycin and neomycin drugs by means of a flow cell coupled to a photometry. At concentrations equal or greater than 2 × 10(-7) mol L(-1) the LSPR band changed its spectral profile. LSPR maximum band, centered at 404 nm, decaied and appeared a new band at 480 nm resulting from the agglomeration of the nanoparticles. Moreover, in a partnership with the Federal University of Pernambuco (UFPE), NPsAg-tartarate were deposited on glass for the realization of thin film with the object to development a biosensor based on localized plasmon resonance (LSPR) for determination of Candida albicans antigen.

Nanoscience dominates virtually every field of science and technology in the 21st century. Nanoparticles are of fundamental interest since they possess unique size- dependent properties (optical, electrical, mechanical, chemical, magnetic etc.), which are quite different from the bulk and the atomic state. Bimetallic nanoparticles are of particular interest since they combine the advantages of the individual monometallic counterparts. The present study focuses on bimetallic nanoparticles containing gold as one of the constituents. Au-Pd, Au-Pt and Au-Ag bimetallic/alloy nanoparticles have been prepared by four different synthetic methods, and characterised by a variety of techniques, with an emphasis on Au-Ag alloy systems in the solution phase as well as in the form of nanostructured films on solid substrates. Au- Ag alloy nanoparticles have been used to demonstrate two different applications. The first is the use of Au-Ag monolayer protected alloy clusters in demonstrating single electron charging events in the solution phase as well as in the dry state. Single electron transfer events involving nanosized particles are being probed extensively due to their potential applications in the field of electronics. The second is an analytical application, involving the use of trisodium citrate capped Au-Ag alloy hydrosols as substrates for surface enhanced Raman and resonance Raman scattering [SE(R)RS] studies. The sols have been used for single molecule detection purposes. Various organic molecules such as quinones, phthalocyanines and methyl violet have been self- assembled in a stepwise manner on the nanoparticulate as well as bulk Au, Ag and Au-Ag surfaces, and characterised extensively by spectroscopic, electrochemical and spectroelectrochemical techniques.

Most of the topics dealt with in this thesis belong to surface science. The starting point was the fundamental understanding of phenomena at the oxide-gas interface and the effect of its modification. Such knowhow was then used to solve (or, at least, to attempt to solve) issues of critical impact in everyday life: the increasing lifetime of building materials employed in low-impact smart houses; the fouling prevention in electroanalytical sensors for neurotransmitter detection; the unspecialized laboratories accessibility to microlithography, critical to device miniaturization. These challenges might seem not related, but they actually share deep scientific and technological foundations. The physicochemical modification of oxide surfaces, the creation of organic/inorganic hybrids and the exploiting / the enhancing of semiconductor peculiar properties allowed us, starting from the foundation, the realization of proof-of-concept protocols and devices, ready for the pre-commercial development. The Leitmotif of my research was the synthesis and the modification of titanium dioxide surfaces. TiO2 has been the main character in physico, physicochemical and material science researches of the last 50 years. Biocompatibility and low cost make it engaging for many applications. Its (near-UV active) semiconductor features, well known and abundantly investigated by the scientific community, are acquiring central interest also in many markets with the development of self cleaning coatings, windows and asphalts, anti-fogging mirrors and self-sterilizing surgery rooms and instrumentations. New generation batteries and solar cells are going to be developed as commercial prototypes. One of the biggest challenges in the titania fundamental research is the enhancement of activity in the solar spectrum. First, the most recent aspects in titania doping and promotion were touched. While, in the last twenty years, great effort has been made in the mono-atomic doping of titania and in the understanding of the influence of the dopant position in the titania lattice and its electronic behavior, the most recent literature describes the co-promotion of the material by two (or more) atoms doping. The metal/non-metal codoping seems especially promising; the synergetic effect of the two atoms in the TiO2 lattice was both theoretically and experimentally proved. In this contest, the N/Nb codoping was analyzed, investigating the effect of the atoms in the lattice from morphological (surface area, porosity and crystallographic structure) and electronic point of view (EXAFS, UV-Vis absorption and EPR analyses). N/Nb codoping was compared with N/Ta co-doped samples, synthesized by two different procedures. The photoactivity of the two sample families was tested by a model reaction (the degradation of ethanol, throughout acetaldehyde intermediate) both under UV and solar simulated irradiation. Then, a different approach in the modification of surfaces was tested. The assembly of organic/inorganic hybrids was tested; thanks to the formation of organic mono- or multi-layers at the surface,they can tune the chemistry, the polarity and the adhesion properties of the interface. Siloxanes were used as active agents, thanks to their compatibility with oxide materials and, especially, for the ability to self-assemble at the surface to form a monolayer. Siloxanes are able to react with the -OH groups at the surface, chemisorbing and polymerizing at the interface in such a way to form a monolayer with tunable functionalities. Many different silanes were tested and their dipole momenta were related to their wettability properties. Such siloxanes chemisorb strongly both from the gas phase and the liquid phase. Their reactivity, both on smooth and rough surfaces, was tested vs the temperature of functionalization in gas phase. Many characterization techniques were adopted to understand the behavior of such molecules from a molecular point of view: magnetic (solid state NMR), microscopic (SEM, TEM, AFM), optical and electrochemical (CV and EIS). The science of adhesion and wettability was also adopted for the development of superhydrophobic coatings. Titanium dioxide particles with engineered morphology were used as the best candidate to create superhydrophobic/superhydrophilic patch-wise surfaces, exploiting their photoactivity (photolithograpy). The core of the thesis was the synthesis, modification and application of transparent photoactive thin films. A procedure for the synthesis of smooth, transparent and photoactive TiO2 thin layers was developed, and used to produce highly applicative devices and protocols. Such synthetic strategy is highly tunable and reproducible; the obtained films are robust and active and, most of all, require simple instrumentation (sol-gel procedure), which is highly appealing for the market. The films were properly characterized both form the morphological/mechanical and photochemical point of view. Apart their transparency and their thickness, the films were highly crystalline (pure anatase phase). Such procedure was firstly designed as a proof-of-concept for self-cleaning windows, but, thanks to its versatility and the high activity of the films, it leads the path towards highly applicative procedures and devices. The smoothness and the photoactivity brought me to the field of photolithograpy, especially in the direction of microlithography. The high activity of the titania allowed the use of safe and low-energetic lamps. No collimation was required to obtain a resolution lower than 5 µm. First of all, I tested the lithography on siloxane monolayer films, as a proof-of-concept of resolution and efficiency. But siloxanes, as many other self-assembled monolayer molecules, can be the pillars for 3D fabrication. Such monolayers were used as polymerization initiators for polymer brushes. If the initiators of polymerization are patterned, patterned polymer brushes will be obtained. That was the first report of polymer-brushes lithography exploiting the photoactivity of TiO2. Remote photocatalytic lithography makes this procedure extremely versatile. Exploiting the remote photocatalysis, in principle, any material can be used as a support for patterned polymer brushes growth (provided that the initiator are able to graft the surface). The developed protocol for the synthesis of TiO2 thin films was also used to design and engineer complex electrodes for cyclovoltammetric analyses of biological samples. Electrochemistry seems to be the best candidate for the development of an analytical option with sensitivity comparable with present analytical procedures but reduced time-per-analysis and cost. Unfortunately, catecholamines chemisorb and polymerize on metal and oxide electrodes quickly, making the device useless. Covering the electrode by a homogeneous, nano-porous thin layer of titania makes the surface photoactive. That is the first example in literature of self-cleaning nano-engineered electrodes for cyclic voltammetry. After the detection, also in simulated human serum and liquor, a fast and simple irradiation of the device, under non-hazardous UV-A lamp, degrades all the fouling on the surface without altering its features. The sensor, after each UV treatment, recovers its pristine performances, with full recovery in terms of selectivity and sensitivity. Irradiation trials were also performed directly in the analytical mixture, as a proof of concept for on-site application. Modern era requires flexible and light materials for the building industry. Polymers are acquiring more and more interest thanks to their increasing performances and their smart properties. The drawbacks of such materials are connected to the low resistance to the UV light, the softness and the difficulties in cleaning procedure. The use of organic/inorganic hybrid, or better the coverage of plastic materials with an oxidic thin layer, can solve many of these problems, lengthening the lifetime of such materials. If the covering oxide is also photoactive, the material can be self-cleaned when exposed to solar light. That is a big chemical challenge, because of many synthetic problems. Two different approaches were tested to solve this relevant issue. On one side, the hydrophobicity of ionic liquid modified SPES (sulfonated polyether sulfone) was combined with designed morphological features to confer superhydrophobicity. On the other side, the polymeric surface was covered with a transparent titania layer active in the near UV-region, able to mineralize organic molecules chemisorbed at the surface. Eventually, a different approach to modify oxidic (and not only) surfaces is the creation of a homogeneous layer of Ag nanoparticles by an innovative microwave procedure. That simple and accessible strategy allowed us to produce plasmonic surfaces (thanks to the dimension and the homogeneity of the Ag particles) with countless applications. The layer was shown to be a very active substrate for surface enhancement Raman spectroscopy (SERS). Thanks to the versatility of the synthetic method, all shapes and dimensions can be covered. That makes it a perfect candidate for the production of new generation of SERS sensors. The sensitivity towards molecules of environmental and biomedical interest was proved.

Silver, gold, and copper metallic nanoparticle films have been utilized in various MEMS devices due to not only their electrical but also their optical properties. The focus of this research is to study the detection at room temperature of carbon monoxide (CO) and hydrogen (H2) via Surface Plasmon Resonance (SPR) phenomenon of silver-embedded Yttrium Stabilized Zirconium (Ag-YSZ) nanocomposite film, gold (Au) nanoparticle film, and an alloy film of silver-copper (Ag-Cu) , grown by the Pulsed Laser Deposition (PLD). To determine the appropriate film materials for quick and accurate CO and H2 detection at room temperature with the PLD technique, the growth process was done repeatedly. Optical tools such as X-Ray Diffraction, Alpha Step 200 Profilometer, Atomic Force Microscopy, and Scanning Electron Microscopy were used to characterize thin films. The gas sensing performance was studied by monitoring the SPR band peak behavior via UV/vis spectrophotometer when the films were exposed to CO and H2 and estimating the percent change in wavelength. The metallic nanoparticle films were tested for concentration of CO (100 to 1000 ppm) and H2 (1 to 10%). Silver based sensors were tested for the cross-selectivity of the gases. Overall the sensors have a detection limit of 100 ppm for CO and show a noticeable signal for H2 in the concentration range as low as 1%. The metallic films show stable sensing over a one-hour period at room temperature. The SPR change by UV/vis spectrophotometer shows a significant shift of 623 nm wavelength between 100 ppm CO gas and dry air at room temperature for the alloy films of Ag-Cu with a wider curve as compared to silver and gold films upon their exposure to CO and H2 indicating an improvement in accuracy and quick response. The results indicate that in research of CO and H2 detection at room temperature, optical gas sensors rather than metal oxide sensors are believed to be effective due to not only the absence of chemical involvement in the process but also the sensitivity improvement and accuracy, much needed characteristics of sensors when dealing with such hazardous gases.

Metallic films, in conjunction with biochemical-targeted probes, are expected to provide early diagnosis, targeted therapy and non-invasive monitoring for epidemiology applications [1-4]. The resonance wavelength peaks, both plasmonic and Wood-Rayleigh Anomalies (WRAs), in the scattering spectra are affected by the metallic architecture. As of today, much research has been devoted to extinction efficiency in the plasmonic region. However, Wood Rayleigh Anomalies (WRAs) typically occur at wavelengths associated with the periodic distance of the structures. A significant number of papers have already focused on the plasmonic region of the visible spectrum, but a less explored area of research was presented here; the desired resonance wavelength region was 400-500nm, corresponding to the WRA for the silver film with perforated hole with a periodic distance of 400nm. Simulations obtained from the discrete dipole approximation (DDA) method, show sharp spectral bands (either high or low scattering efficiencies) in both wavelength regions of the visible spectrum simulated from Ag film with cylindrical hole arrays. In addition, surprising results were obtained in the parallel scattering spectra, where the electric field is contained in the XY plane, when the angle between the metallic surface and the incident light was adjusted to 14 degrees; a bathochromic shift was observed for the WRA peak suggesting a hybrid resonance mode. Metallic films have the potential to be used in instrumental techniques for use as sensors, i.e. surface plasmon resonance affinity biosensors, but are not limited to such instrumental techniques. Although the research here was aimed towards affinity biosensors, other sensory designs can benefit from the optimized Ag film motifs. The intent of the study was to elucidate metal film motifs, when incorporated into instrumental analysis, allowing the quantification of genetic material in the visible region. Any research group that routinely benefits from quantification of various analytes in solution matrices will also benefit from this study, as there are a bewildering number of instrumental sensory methods and setups available.
B.S.
Bachelors
Sciences
Chemistry

碩士
國立東華大學
材料科學與工程學系
106
In this study, reactive magnetron sputtering was used to prepare different nitrogen doped titanium dioxide film (N-TiO2), which was combined with silicon dioxide layers and Ag nanoparticles (Ag NPs) to form a sandwich multilayer structure. The surface plasmon effect of Ag NPs could enhance the absorption of visible light of the film, and might improve the photocatalytic properties of titanium dioxide. The structure and crystallinity of the films were analyzed by XRD. The elemental composition and bonding of the films were examined by XPS. UV-vis spectrotometer was used to study the absorption phenomena of the films. The photocatalytic efficiency properties of the films under visible-light illumination were evaluated by measuring the decomposition rate of methylene blue in aqueous solution. From the experimental results, with the increase of silver sputtering time, the content and the size of silver nanoparticles increased which resulted in enhancement of visible light absorption of the films, but the rate of increase is limited. The silver nanoparticles may combine with the oxygen in the air or with the oxygen of TiO2 films and get oxidized, which reduce the surface plasmon effect of the nano-silver and as a result decrease the visible light absorption of the film. For this reason, SiO2 layers were deposited above and below silver layer to protect from oxidizing. At 30 seconds (Ag30-NT) deposition time of Ag, the distribution of Ag nano-particle size is uniform, so we used this parameter to deposit N-TiO2/SiO2/Ag/SiO2/N-TiO2 multilayer. This structure can provide Ag NPs with good surface plasmon effect and enhance the absorbance of the films in the visible light. However, the film didn’t show significant photocatalytic property. The possible reason is that SiO2 layer is too thick, which makes electron and hole pairs of the film hard to reach the surface of the film and could not exhibit significant photocatalytic property. When the nitrogen flow rate is 20 sccm, N-TiO2 has 16.9 at% of nitrogen content. The phases of the film obtained were anatase, Ti3O5 and TiN. The absorption in the visible light of 20 sccm nitrogen doped with TiO2 (N20T) is 3-4 times higher than TiO2 film. In addition, depositing anatase TiO2 on sample N20T, improved the photocatalytic phenomenon about 80% compared to that of pure TiO2 films. So the catalytic properties of photocatalyst films were affected by the absorbance and surface properties of the films.

碩士
明志科技大學
材料工程研究所
98
Ag and Cu, when used as dopants, are proved immiscible with TaN, which makes the synthesis of TaN -Ag or -Cu nanocomposite thin films possible [5]. Recently, it was reported that the mechanical properties of Ag- or Cu- doped TaN films could be improved after rapid thermal annealing (RTA), due to the formation of metal nanoparticles in the matrix. In a previous study, it was also shown that Ag and Cu particles could form on the surface of TaN, which consequently made these TaN-metal nanocomposite promising antibacterial films. It is found that the anti-bacterial efficiency depends on metal type, emerged particle size, and total exposed metal amount. However, up to date, there is no study on the comparison of TaN-Cu and TaN-Ag against Gram-negative (ex: E. Coli.) and Gram-positive (ex: S. aureus) bacteria. Also, there is no study on the possibility of rejuvenation for these films. Furthermore, there is no study on TaN-(Cu,Ag) composite thin films. The present study makes attempts to (1) compare the anti-bacterial efficiency of TaN-Ag and TaN-Cu against E. coli and S. aureus, (2) study the rejuvenating behavior of TaN-Cu thin films, and (3) study the anti-bacteria and anti-wear behaviors of TaN-(Cu,Ag) thin films. It is hoped that these films would combine the advantages of TaN-Ag and TaN-Cu. TaN-Cu, TaN-Ag and TaN–(Cu,Ag) nanocomposite films were deposited by reactive co-sputtering on Si and tool steel substrates. TaN-Cu and TaN-Ag films were then annealed using RTA (Rapid Thermal Annealing) at 400C for 2, 4, 8, 15 minutes respectively, TaN-(Cu,Ag) films were then annealed using RTA at 200, 250, 300, 350, 400C for 4 minutes respectively to induce the nucleation and growth of metal particles in TaN matrix and on film surface. C-AFM (Conductive Atomic Force Microscopy), FESEM (Field-emission Scanning Electron Microscopy) were applied to characterize the size of metal nano-particles emerged on the surface of these thin films. The effect of annealing on mechanical and anti-bacterial properties of these films was studied. A nano-indenter and a pin-on-disc tribometer were used to study the effect of annealing on the films’ mechanical properties. On the other hand, ICP-MS (Inductively Coupled Plasma Mass Spectrophotometer) was applied to characterize the Cu and Ag ion’s dissolving rate. The samples were tested for their anti-bacterial behaviors against Gram-negative and Gram-positive bacteria. The antibacterial efficiency was correlated with Ag and Cu ion concentrations in buffer solution. Under similar ion concentrations, it is concluded that Ag ion or TaN-Ag is more effective against E. Coli (Gram-negative), while Cu ion or TaN-Cu is more effective against Staphylococcus aureus (Gram-positive). Part of this study is aiming at the rejuvenating behavior of TaN-Cu nanocomposite thin films. After being rejuvenated, TaN-Cu films appear to recover their antibacterial behaviors. However, the mechanical properties of TaN-Cu nanocomposite thin films would deteriorate with the increased number of rejuvention. For the study of TaN-(Cu,Ag) nanocomposite films, the results show that these films could be annealed at a temperature as low as 250℃, and exhibit excellent antibacterial property against E.coli and S.aureus. The antibacterial efficiency may increase with the increase of annealing temperature. Furthermore, hardness may increase with the increase of annealing temperature, while friction coefficient and wear rate decrease with the increase of annealing temperature.

碩士
逢甲大學
纖維與複合材料學系
102
This study is divided into three parts. The first part is the preparation of sodium alginate /polyvinyl alcohol composite films. After the solution with 3 wt% sodium alginate and 15 wt% polyvinyl alcohol was mixed. The FT-IR and VVSEM show there are only hydrogen bond and a good compatibility. The mechanical properties showed SAP82 have the best strength at break 46.8 MPa and it increase 324%. From TGA, the decomposition temperature of films increased from 248.46 ℃to 265.22 ℃with increasing PVA content. The second part is the preparation of the nano silver /sodium alginate film. We use of 3 wt% sodium alginate as a protective agent, silver nitrate as silver nanoparticles reduction by using oxidation-reduction methods in the sodium alginate solution, then obtained the nano silver/ sodium alginate films. By UV-vis, EDS, TEM, SPSA, VVSEM analysis confirmed the presence of nano-silver having an average particle size of all less than 100 nm, The mechanical properties and antibacterial analysis showed Ag1000SA have the best strength at break 80.37 MPa and it increase 180%, and have a degree of antibacterial effect. The rheological analysis results display that with increasing shear rate and temperature, the apparent viscosity of the solution fall. And with nano-Ag content had increased Non-Newton index will decrease first and then increased. The third part is the preparation of the best ratio of nano silver in second part / sodium alginate / polyvinyl alcohol composite film. By adding polyvinyl alcohol, investigate the effect of different amounts of nano silver / sodium alginate / polyvinyl alcohol films. From UV-vis, VVSEM contain silver nanoparticles and particle size are smaller than 100 nm, remained nanoscale. The mechanical properties showed the strength at break of samples containing the best ratio of the silver nanoparticles are better than non-contained samples. With the increase in the proportion of polyvinyl alcohol, to improve the elongation at break 657%.

碩士
國立嘉義大學
電子物理學系研究所
99
Abstract In the experiment, we make use of localized surface plasmon resonance to produce a novel polymer light emitting diodes (PLEDs). Ag film with mass thickness of 2-nm is annealed to be a nano-particles layer and then gallium zinc oxide is deposited on it at substrate temperture of 150℃ by pulsed laser deposition to form a window materials for PLEDs. The PFO coated by spin coating method is used as an emissive layer. The LiF and Al films are used as an electron injection layer and cathode, respectively. From the research results, the larger particles caused from the thicker layer of Ag film after annealing. There are not only an absorption peak appeared but also red shift after GZO were deposited on Ag nano-particles. In electrical characteristics, all resistivities attain 10-4 Ω-cm by Hall measurement that meet the requirements of the literature. The high-current region were increased when GZO were deposited on Ag nano-particles. The luminance-voltage measurements show that the absorption band of the Ag nanoparticles due to the surface plasmon resonance effect increased the general luminescence efficiency of the PLED device by 100%.

博士
國立清華大學
電子工程研究所
92
In this dissertation, two topics are discussed. The first part is concerning the rotational anisotropy SHG studies of the group-III nitride compound films on Si(111) substrates. The symmetry behavior of AlN/Si(111) and GaN/AlN/Si(111) structures grown by molecular beam epitaxy (MBE) have been analyzed by measuring the rotational dependence of the polarized second harmonic generation intensity for different polarized fundamental beams. The crystalline structure has also been checked by reflection high-energy electron diffraction (RHEED), X-ray diffraction and photoluminescence (PL) spectroscopy. Considering various contributions of the nonlinear response from the bulk and interfaces, the interface strain implies an nonuniform inhomogeneous intensity variation of second harmonic generation as functions of the surface azimuthal rotation angle ψ.Therefore, the observation of nonlinear optical effect provides a valuable illustration of the epitaxy quality and growth parameter characterization by a nondestructive method. The second part is about the rotational anisotropy SHG studies of Ag thin films and nanoparticles on Si(111) substrates. The asymmetric distributions of the surface optical second harmonic generation (SHG) through azimuthally angular scans for thin silver films deposited on Si(111) wafers have been detected with different polarizations of output beams. On account of the inversion symmetry of silicon crystals, the SHG for the Ag/Si system is mainly contributed from silver film and silicon surface. In this work, we found that the interface strain implies an asymmetric intensity variation of SHG with respect to the surface azimuthal angle as an ultra thin Ag film is deposited on silicon wafers. This asymmetric behavior is prominent as the deposited silver layer is heated to change from a continuous film to granular nanoparticles. Similar change of the surface asymmetric SHG is observed for a bare Si wafer imposed with an external force or adsorbed with a drop of epoxy glue.

碩士
逢甲大學
紡織工程所
97
In this research, Ag nanoparticles were reduced in pseudo-thermoplastic polyvinyl alcohol (TPVA) solutions by the in-situ chemical reduction method, and then compared to the particle size and dispersibility of TPVA which added market Ag nanoparticles. Moreover the mechanical, antibiotic and acetal properties of reduced Ag nanoparticles/pseudo-thermoplastic polyvinyl alcohol (Ag-TPVA) films were studied. From the experimental results and statistics analysis, the particle size and dispersibility of reduced Ag nanoparticles on TPVA (R-TPVA) were more excellent than market Ag nanoparticles. The tensile test indicates that Ag nanoparticles content increased and the strength decreased, because the defects resulting the stress concentration, and the TPVA films which added 1/100 Ag nanoparticles (R1-TPVA) had still great strength. The antimicrobial activity of R-TPVA films were investigated by JIS L 1902：2002, R-TPVA films had great antibiotic effect. By IR analysis, Ag-TPVA films had an effective acetal formation and the acetal formation was unaffected by Ag nanoparticles. Accroding to the antimicrobial test, the antibiotic effect of R1-TPVA films during acetal formation (R1-CTPVA) less than R1-TPVA films, but R1-CTPVA films had still excellent antibiotic effect. Therefore, R1-TPVA films have great strength (67.78 Mpa) and antibiotic effect for industry application (The sterilization and bacteriostasis values are 5.6 and 3.1, respectively).

Chapter I: This chapter briefly gives an introduction about microorganisms, their varieties, growth, reproduction etc. In particular, about bacterial function. A sincere attempt is made to review this briefly, including an account of the studies already reported in the literature. Chapter II deals with the antimicrobial activity of Ag/agar film on Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Candida albicans (C. albicans). In particular, films were repeatedly cycled for its antimicrobial activity. The antimicrobial activity of Ag/agar film was found to be in the order, C. albicans > E. coli > S. aureus. Chapter III describes the synthesis of Ag@AgI NPs in agarose matrix. A detailed antibacterial studies including repetitive cycles are carried out on E. coli and S. aureus bacteria. EPR and TEM studies are carried out on the Ag@AgI/Agarose and the bacteria, respectively, to elucidate a possible mechanism for killing of the bacteria. The hybrid could be recycled for the antibacterial activity many times and is found to be non toxic towards human cervical cancer cell (HeLa cells). Chapter IV reports the antibacterial efficacy of silver nanoparticles (Ag NPs) deposited alternatively layer by layer (LBL) on chitosan polymer in the form of a thin film over a quartz plate and stainless steel strip against E. coli. AFM studies are carried out on the microbe to know the morphological changes affected by the hybrid film. The hybrid films on aging (3 months) are found to be as bioactive as before. Cytotoxicity experiments indicated good biocompatibility. Chapter V describes the fabrication of carbon foam porous electrode modified with reduced graphene oxide-Ag nanocomposites. The device can perform sterilization by killing pathogenic microbes with the aid of just one 1.5V battery with very little power consumption. Chapter VI Here we have studied in particular a property say the influence of surface defect in the production of ROS by ZnO NPs and in turn the bactericide activity. Secondly, a homogeneous ZnO and ZnO/Ag nanohybrid has been synthesized by employing chitosan as mediator. The synergistic antibacterial effect of ZnO/Ag nanohybrid on bacteria is found to be more effective, compared to the individual components (ZnO and Ag). A possible mechanism has been proposed for the death of bacteria by ZnO/Ag nanohybrid, based on EPR studies and TEM studies.

碩士
國立成功大學
化學工程學系碩博士班
93
In the thesis, Ag nanoparticle-containing AZO colloid solutions were prepared by sol-gel method and further used to form the corresponding transparent conducting films via spin-coating and heat treatment. The elevation of various processes, and the effects of the addition of Ag nanoparticles and heat treatment on the optical property and conductivity of AZO films were studied. 　According to the conductivity, the transparency in visible region, and the uniformity of thin films, various preparation methods were elevated and designed, including alcohol reduction method, organic base-catalyzed reduction method, hydrazine reduction method, and the use of aluminum salts (AlCl3 and Al(NO3)3). It was found that the alcohol reduction method with AlCl3 as the precursor was the most suitable one for the preparation of Ag nanoparticle-containing AZO films. Thus, this process was used for the followed investigations in this study. 　By investigating the effect of the amount of Ag nanoparticles, it was found that the addition of Ag nanoparticles could significantly enhance the conductivity of AZO films. When the Ag content was 0.05 at.% relative to Zn, the electrical resistivity of AZO film was as low as 6.94×10-3 Ω•cm after annealing in air at 600℃ and heat treatment with hydrogen at 400℃. The UV/VIS spectra revealed that the transparency of Ag nanoparticle-containing AZO films has no significant difference from that of pure AZO films. The transmittance of Ag nanoparticle-containing AZO films was higher than 85% in the visible region. However, the addition of Ag nanoparticles might result in the slightly decrease of transmittance around 500 nm due to the optical absorption of Ag nanoparticles. 　From the effect of heat treatment with hydrogen on the properties of AZO films, it was found that the electrical resistivity could be further decreased to 1.72×10-3 Ω•cm when Ag content was 0.10 at.% and the heat treatment with hydrogen was performed at 500℃ and a gauge pressure of 0.4 kg/cm2 . The electrical resistivity was much lower than the reported values of AZO films obtained by sol-gel method in the literature.

碩士
國立成功大學
化學工程學系碩博士班
95
This thesis concerns the preparation of Ag nanoparticle-containing Al-doped zinc oxide (AZO) thin films and AZO@Au nanoparticles. For the former, Ag nanoparticle-containing AZO thin films were prepared by the spin-coating of Ag nanoparticles-containing AZO sol and the followed air and hydrogen heat treatments. The effects of Al/Zn atomic ratio on the conductivity and band gap energy of thin films were investigated. For the latter, AZO nanoparticles were synthesized in 2-methoxyethanol with reflux first and then Au nanoparticles were deposited on the surface of AZO. The optical property of the resultant AZO@Au nanoparticles was investigated to evaluate their application in thin films. For the study on the sol-gel synthesis of Ag nanoparticle-containing AZO thin films, from the effect of Al/Zn atomic ratio (0.5-3.0), it was found that the highest conductivity after calcination in air was obtained at Al/Zn=1.5 at.%. However, after hydrogen heat treatment, the effect of Al/Zn atomic ratio was not significant. This revealed that the conductivity enhancement by hydrogen heat treatment was more effective than by the doping of Al. When Al/Zn=1.5 at.% and the hydrogen heat treatment was improved, the lowest electric resistivity of 5.92×10-4 Ω-cm was obtained. For the preparation of AZO@Au nanoparticles, at first, the well dispersed secondary particles of AZO nanoparticles were synthesized in 2-methoxyethanol with reflux. Their mean diameter was about 143 nm. Secondary, AZO@Au nanoparticles were prepared further. When Au nanoparticles were coated on the surface of AZO by sodium borohydride reduction, the modification of AZO with sodium citrate could avoid the hydrolysis of AZO. When the electroless plating technique was used for the coating of Au on the surface of AZO, the impurity derived from the Sn-based sensitizer was generated and serious hydrolysis was observed. Using few Au nanoparticles on the surface of AZO as the seeds to grow Au nanoparticles by formaldehyde reduction, it was found that the product exhibited an absorption peak around 550 nm, contributed from the Au nanoparticles deposited on the surface of AZO or the aggregates of Au nanoparticles formed in the bulk solution. After the gradual hydrolysis of AZO cores, the deposited Au nanoparticles were aggregated, yielding the absorption from 600-900 nm.

碩士
義守大學
電子工程學系
102
In this study, we deposit Ag nanoparticles (Ag NPs)-doped carbon nanotube (CNT) suspension on metal by spray technique to produce a high current density carbon nanotube field emission electron source substrate. Field emission organic light-emitting diodes (FEOLEDs) are fabricated by combining the CNT field emission electron source with organic light-emitting diodes (OLEDs), which demonstrate a higher luminous efficiency than OLEDs. The study of a CNT field emission electron source substrate is to enhance the field emission characteristics. First, Cu, Ag or Al is evaporated on the glass substrate to form the cathode. Ag NPs-doped multi-walled carbon nanotubes (MWCNTs) are deposited onto cathodes by spray technique. Doping Ag NPs into CNTs can improve the conductivity of CNTs film to further enhance the field emission properties. Experimental results reveal that a current density of 62.5 mA/cm2 at 1.78 V/μm has been obtained when Cu is used as a cathode and 6.6 wt% Ag NPs is doped into CNTs. When the above electron emitting source used as a substrate combines an OLED device to form a FEOLED, the luminance intensity is enhanced from 5857 cd/m2 to 7386 cd/m2 and the luminous efficiency is enhanced from 9.327 cd/A to 11.76 cd/A.

碩士
國立臺灣科技大學
材料科學與工程系
100
Modified multi-walled carbon nanotube (MWNT), MWNT-C2H4COOH, obtained by the reaction of MWNT with succinic acid acyl peroxide (SAAP), reacted sequentially with SOCl2 and PPG-g-FA to afford another modified MWNT, MWNT-C2H4CO-PPG-g-FA (denoted as MWNT-PPG-g-FA). MWNT-C2H4COOH reacted with azide (N3-) ion to yield the third modified MWNT, MWNT-C2H4NH2. The dispersedness and particle size of the three modified MWNTs in water were investigated. The modified poly(ethylene terephathalate, PET) film which could form hydrogen bond with the modified MWNTs was prepared by spin-coating of P4VP on the PET film (called P4VP/PET). The transparent MWNT conductive film decorated with Ag nanoparticles was prepared by dip-coating the modified MWNTs via layer-by-layer assembly on the P4VP/PET and followed by chelating-reducing the Ag+ ions on the MWNT conductive film. The conductivity and the optical transmittance of the film were recorded by 4-point probe and UV-vis spectrometer. The morphology of and the existence of silver on the film were investigated by the scanning electron microscope (SEM) and the X-Ray Photoelectron Spectroscpoe (XPS).

Dissertação de mestrado em Ciências – Formação Contínua de Professores (área de especialização em Física e Química)
Este projeto insere-se numa das linhas de investigação do Grupo de Revestimentos Funcionais (GRF) que tem como objetivo o estudo de propriedades de filmes finos para diversas aplicações óticas. No âmbito desta proposta de tese, pretende-se dar seguimento a um projeto de investigação aprovado pela Fundação para a Ciência e Tecnologia. Produziram-se diversos filmes finos de TiO2(Au) e TiO2 (Ag), usando a técnica de pulverização catódica reativa em magnetrão, com alimentações de corrente contínua, CC. Para se produzir os filmes referidos, utilizou-se um alvo de titânio com 99.9 % de pureza, onde se colocaram pequenos pedaços de ouro ou de prata na superfície do referido alvo. Seguidamente, fez-se a caracterização dos filmes através das técnicas de espectrometria de retrodispersão de Rutherford (RBS) (composição química), difração de raios-X (XRD) (estrutura cristalina) e microscopia eletrónica de varrimento (SEM) (morfologia e espessura), bem como dos coeficientes óticos (transmitância e refletância). Para determinar a resistividade elétrica dos filmes finos produzidos, utilizou-se o método das 4 pontas para as amostras condutoras e o método das 2 pontas para as amostras isoladoras. Finalmente, colocou-se os filmes finos em banhos de suor artificial a diferentes durações, para estudar de que modo a duração e o suor artificial alteram os coeficientes óticos e a resistividade elétrica.
This project belongs to one of the lines of research of the Functional Coatings Group (GRF) that aims to study the properties of thin films for various optical applications. Within this thesis proposal, it is intended to continue a research project approved by the Foundation for Science and Technology. Were produced several TiO2 (Au) and TiO2(Ag) thin films, using the technique of reactive magnetron sputtering, with current power sources, DC. To produce such films, it was used a titanium target with 99.9 % purity, where were placed small pieces of gold or silver on the surface of the referred target. Then, it was made the characterization of the films by Rutherford backscattering Spectrometry (RBS) (chemical composition), X-ray diffraction (XRD) (crystal structure) and scanning electron microscopy (SEM) (morphology and thickness) techniques as well as of the respective optical coefficients (transmittance and reflectance). To determine the electrical resistivity of the thin films produced, it was used the four-point probe method for the conductive samples and the two-point probe method for the insulating samples. Finally, the thin films were placed in artificial sweat baths at different durations, to study how the duration and the artificial sweat alter the optical coefficients and the electrical resistivity.

Dissertação de mestrado em Engenharia de Materiais
As nanopartículas de metais nobres, como o ouro (Au) e a prata (Ag), começaram a ser usados há muitos séculos, proporcionando cores diferentes nas janelas das catedrais medievais e em taças romanas antigas. Hoje em dia, o interesse em materiais nanocompósitos contendo nanopartículas de metais nobres, incorporados em matrizes dielétricas, está relacionado com a sua potencial utilização numa ampla gama de aplicações tecnologicamente avançadas. A investigação deste potencial tem sido direcionada para a deteção ambiental e biológica, e para o desenvolvimento de novas cores para revestimentos funcionais. A maior parte destas aplicações baseiam-se no chamado efeito de ressonância de plasmões de superfície localizados. Este fenómeno físico depende do tipo das nanopartículas de metais nobres, da sua distribuição, do tamanho e forma, bem como das características dielétricas da matriz onde se encontram dispersas. Este trabalho foi desenvolvido no âmbito de um projeto financiado pela Comissão Europeia (Nano4color). Teve como objetivo principal estudar e correlacionar as alterações morfológicas e estruturais, resultantes da incorporação de nanopartículas de Au e/ou Ag, e do tratamento térmico realizado, nas propriedades óticas dos filmes finos de forma a desenvolver uma nova gama de cores para revestimentos funcionais De forma a verificar de que forma as mudanças no tamanho, forma e distribuição das nanopartículas representam parâmetros fundamentais para a otimização das propriedades dos materiais plasmónicos, um conjunto de três sistemas, com diferentes concentrações de Ag, de Au e de Ag / Au disperso(s) em dióxido de titânio (TiO2), foram preparados. Os filmes finos foram depositados por pulverização catódica reativa por descarga magnetrão de corrente contínua. Posteriormente, as amostras depositadas foram submetidas a um tratamento térmico ao ar com o objetivo de promover a aglomeração de nanopartículas de Au, de Ag e de Ag/Au. Demonstrou-se que a concentração de Ag, Au ou de Ag/Au, bem como os tratamentos térmicos realizados, afetam a cor e propriedades óticas dos filmes produzidos.
Nanoparticles of noble metals, such as gold (Au) and silver (Ag), began to be used for centuries, providing different colors on the windows of medieval cathedrals and ancient Roman glasses. Nowadays, the interest in materials nanocomposites containing nanoparticles of noble metals, embedded in dielectric matrices, is related to its potential use in a wide range of technologically advanced applications. The investigation of this potential has been directed to environmental and biological detection, and to develop new colors for functional coatings. Most of these applications are based on the localized surface plasmon resonance. This physical phenomenon depends on the type of nanoparticles of noble metals, their distribution, size and shape, as well as the dielectric characteristics of the matrix where they are scattered. This work was developed under a project funded by the European Commission (Nano4color). Had as main objective study and correlate the morphological and structural changes resulting from the incorporation of Au nanoparticles and/or Ag, and the heat treatment performed in the optical properties of thin films in order to develop a new range of colors for functional coatings in order to check how changes in size, shape and distribution of the nanoparticles represent basic parameters for optimizing material properties plasmónicos , a set of three systems, with different concentrations of Ag, Au and Ag/Au dispersed on titanium dioxide (TiO2), have been prepared. The thin films were deposited by reactive sputtering by DC magnetron discharge. Subsequently the deposited samples were subjected to a thermal treatment in air in order to promote the agglomeration of Au nanoparticles, Ag and Ag / Au. It was demonstrated that a concentration of Ag, Au or Ag/Au, as well as the heat treatments carried out, affect the color and optical properties of films produced.