Dissertations / Theses: 'Graphene silver nanocomposite films'

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Stone, D'Arcy S. "Tribological investigation of nanocomposite thin films of transitional metal nitrides with silver inclusions." OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/768.

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In this tribological study, a temperature dependent inquiry of the changes in chemistry and crystal structure of two selected double metal oxides is undertaken. It is known that chameleon coatings of Mo2N/Ag/MoS2 produce a friction coefficient of 0.1 from wear testing at 600 °C for 300,000 cycles. The low friction is attributed to the formation of silver molybdates layers, a lubricious double-metal oxide, in the coating. Double-metal oxides consisting of a group 6 transitional metal and silver (silver molybdate (Ag2Mo2O7) and silver tungstate (Ag2WO4)) were used for this investigation. Thin films and powders were investigated using high temperature x-ray diffraction, high-temperature Raman spectroscopy and differential scanning calorimetry in tandem with sliding tests from 25 to 600 °C. Our results were compared to external ab-initio molecular dynamic simulations performed elsewhere to qualify experimental results. The layered atomic structure of silver molybdate facilitates sliding, resulting in a low coefficient of friction (<0.2) from 300-500 °C. Unlike Ag2Mo2O7, however, Ag2WO4 does not possess a layered atomic structure and produced coefficients of friction (>0.4) in all temperature ranges between room temperature and 500 °C. Applying the knowledge gained from prior studies of the intrinsic properties of double metal oxides of group 6, chameleon coatings consisting of group 5 transitional metal nitrides (vanadium nitride, niobium nitride, and tantalum nitride) with silver inclusions were created using unbalanced magnetron sputtering to investigate their potential application as adaptive, friction reducing coatings. The coatings were tribotested against a Si3N4 counterface in the 22 to 1000 °C temperature range. In-situ Raman Spectroscopy measurements were taken during heating and wear testing at 700 °C to identify the evolution of phases in the coatings' surfaces and in the wear track. The chemical and structural properties of the coatings were also characterized before and after wear testing using x-ray diffraction. At higher temperatures, oxygen, silver and the transition metals react on the surface to form potentially lubricious double oxide phases (silver vanadate, silver niobate and silver tantalate). All coatings performed similarly up to 750 °C. The VN/Ag coating, however, had a lower coefficient of friction at 750 °C comparatively to TaN/Ag and NbN/Ag, likely due to its reported lower melting temperature (450 °C) and its layered crystal structure.

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Abelard, Joshua Erold Robert. "Silver-Polyimide Nanocomposite Films: Single-Stage Synthesis and Analysis of Metalized Partially-Fluorinated Polyimide BTDA/4-BDAF Prepared from Silver(I) Complexes." W&M ScholarWorks, 2010. https://scholarworks.wm.edu/etd/1539626900.

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Sass, Danielle. "Nano silver-Iron-reduced graphene oxide modified titanium dioxide photocatalyst for the remediation of Organic dye in water systems." University of the Western Cape, 2018. http://hdl.handle.net/11394/6274.

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Magister Scientiae - MSc (Chemistry)
Drinking water with high concentrations of inorganic and organic contaminants can cause adverse health defects. Specifically methyl orange dye is an organic water contaminant that has been known (along with others like methyl blue etc.) to have an increase in our water systems over the past few years due to increasing demand in industrial processes. It is therefore of utmost importance to remediate organic contaminants and ultimately enable prevention. The contaminants can be removed by photocatalysis. Anatase TiO2 is known for its photocatalytic degradation of environmental pollutants and photoelectro-chemical conversion of solar energy. However its application is limited since it is a wide band gap semiconductor, (Eg = 3.2 eV). The following study deals with the enhancement of the photocatalytic properties of TiO2 for remediation of organic water contaminants. The study was carried out to produce the two nanocomposites AgFe-TiO2 and AgFe-TiO2-rGO photocatalyst which purpose is to be cheap and easy to apply, with improved (fast and effective) photocatalytic degradation of methyl orange. The main objective was to decrease the band gap and to introduce intra-band gap states to absorb visible light. Modification of the TiO2 with small bandgap semiconductor, graphene and Ag- Fe nanoalloy reduced the bandgap energy for visible light absorption and photocatalytic degradation of methyl orange dye. The two composites were synthesised using sonication and chemical synthesis methods. A photocatalytic study (degradation of methyl orange dye) was carried out using a system incorporating an UV lamp source to determine the degradation of methyl orange catalysed by the synthesised photocatalysts AgFe-TiO2-rGO and AgFe-TiO2 along with UV-vis Spectroscopy. Morphological studies were carried out using HRSEM and HRTEM which determined the spherical agglomerated nature of AgFe-TiO2 and the sheet-like nature of AgFe-TiO2-rGO containing spherical agglomerants but that also contained pockets formed by the sheets of the rGO. XRD served as confirmation of the phase of TiO2 in both composites to be anatase. Analysis confirmed the formation and elemental determination of both composites. It was observed that the Band gap of TiO2 degussa decreased from 2.94 eV to 2.77 eV in the composite AgFe-TiO2. The photocatalytic reactivity of AgFe- TiO2 was an improvement from TiO2 and AgFe-TiO2-rGO based on the photocatalytic study. Therefore concluding that AgFe-TiO2 was the best catalyst to convert the dye (Orange II) into free radicals and ultimately remove the contaminant from the water compared to AgFe-TiO2-rGO.

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Kaouk, Ali [Verfasser]. "Plasma Enhanced Chemical Vapour Deposition of Graphene-Hematite Nanocomposite Films as Photoanodes in Water-Splitting Reactions / Ali Kaouk." München : Verlag Dr. Hut, 2016. http://d-nb.info/1100967753/34.

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Sass, Danielle Thandi. "Nano silver-iron-reduced graphene oxide modified titanium dioxide photocatalyst for the remediation of organic dye in water systems." University of the Western Cape, 2018. http://hdl.handle.net/11394/6410.

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Magister Scientiae - MSc (Chemistry)
Drinking water with high concentrations of inorganic and organic contaminants can cause adverse health defects. Specifically methyl orange dye is an organic water contaminant that has been known (along with others like methyl blue etc.) to have an increase in our water systems over the past few years due to increasing demand in industrial processes. It is therefore of utmost importance to remediate organic contaminants and ultimately enable prevention. The contaminants can be removed by photocatalysis. Anatase TiO2 is known for its photocatalytic degradation of environmental pollutants and photoelectro-chemical conversion of solar energy. However its application is limited since it is a wide band gap semiconductor, (Eg = 3.2 eV). The following study deals with the enhancement of the photocatalytic properties of TiO2 for remediation of organic water contaminants.
2021-12-31

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Pugliara, Alessandro. "Elaboration of nanocomposites based on Ag nanoparticles embedded in dielectrics for controlled bactericide properties." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30324/document.

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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

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Ly, Kally Chein Sheng 1992. "Fabricação e caracterização de filme fino regenerável hidrofóbico." [s.n.], 2017. http://repositorio.unicamp.br/jspui/handle/REPOSIP/330349.

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Orientador: Antonio Riul Júnior
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
Made available in DSpace on 2018-09-02T14:50:41Z (GMT). No. of bitstreams: 1 Ly_KallyCheinSheng_M.pdf: 2442128 bytes, checksum: 86716c6c19fa3a9db425b32c36463141 (MD5) Previous issue date: 2017
Resumo: Materiais biomiméticos são inspirados em estruturas biológicas para a obtenção de propriedades e funcionalidades específicas. Dentre os materiais biomiméticos, os que são capazes de se regenerar (self-healing) despertaram grande interesse pelo potencial de aplicação em diversas áreas. Para ilustrar, alguns materiais autorregeneráveis poliméricos apresentam regeneração múltipla, necessitando apenas de água para que a regeneração ocorra em alguns minutos, aumentando consideravelmente a proteção mecânica da superfície contra desgastes, danos mecânicos entre outros. Entretanto, múltiplas imersões em água ou em meios aquosos pode degradar o material e neste contexto este projeto visa incorporar a hidrofobicidade a um sistema regenerável. Desta forma, o material regenerável hidrofóbico, durante sua regeneração imersa em água, poderá diminuir a interação da superfície não danificada com a água, reduzindo corrosões e degradações devido a meios aquosos. Estudamos a nanoestruturação de materiais através da técnica de automontagem por adsorção física (LbL, do inglês Layer-by-Layer) utilizando os polieletrólitos poli(etileno imina) (PEI) e poli(ácido acrílico) (PAA), a fim de produzir revestimentos capazes de se regenerar a danos mecânicos micrométricos. Adicionalmente, foram incorporados a estes dois materiais nanofolhas de óxido de grafeno reduzido (rGO) funcionalizados com poli(cloridrato de alilamina) (GPAH) e poli(estireno-sulfonato de sódio) (GPSS), com o intuito de verificarmos um aumento de resistência a abrasão do material e alterações nas propriedades elétricas na nanoestrutura formada para aumentar o potencial de aplicação em eletrônica flexível. A arquitetura molecular (GPAH-PEI/GPSS-PAA)60 foi caracterizada com espectroscopia Raman, medidas de ângulo de contato, microscopia de força atômica, medidas elétricas e nanoindentação. Foi observada boa regeneração do material após 15 minutos de imersão em água a temperatura ambiente em um dano mecânico da ordem de 10 micrômetros. Também observamos boa hidrofobicidade do filme LbL (GPAH-PEI/GPSS-PAA)60 ( teta = 136º), e medidas de microscopia de força atômica e perfilometria indicaram, respectivamente, rugosidade superficial de 55 nm em uma área de (2 ?m x 2 ?m) e espessura de filme de 30 ?m. A análise Raman apontou para uma forte interação das nanofolhas de rGO com os polímeros, corroborando o tem caráter elétrico isolante do filme (GPAH-PEI/GPSS-PAA)60, que apresentou função trabalho ~ 5,2 eV e condutividade elétrica da ordem de 10-7 S/cm, que acreditamos resultar das fortes interações das nanofolhas com os polímeros. Por fim, medidas de nanoindentação indicaram que a incorporação de nanofolhas de GPSS e GPAH aumentou em 10 vezes a dureza do nanocompósito formado, sem comprometer a regeneração
Abstract: Biomimetic materials are inspired in biological structures to obtain specific properties and functionalities and among them, those capable of self-healing brought great interest due to high potential of application in different areas. To illustrate, some polymeric self-healing materials present multiple regeneration in the presence of water, with the regeneration occurring within a few minutes, increasing considerably the mechanical protection of a surface against wear and mechanical damage among others. Nevertheless, multiple immersions in water or in aqueous media can degrade the material and in this context this project aims the incorporation of hydrophobicity to a self-healing system. In this way, the self-healing, hydrophobic material during its immersion in water may decrease the interaction of the damaged surface with water, reducing corrosion and degradation due to aqueous media. We study the nanostructuration f materials through the layer-by-layer (LbL) technique using poly(ethylene imine) (PEI) and poly(acrylic acid) (PAA) in order to produce self-healing coatings from micrometric mechanical damages. In addition, we also incorporate to these materials reduced graphene oxide (rGO) functionalized with poly(allylamine hydrochloride) (GPAH) and poly(styrene-sodium sulfonate) (GPSS), with the purpose of verifying an increase in the mechanical abrasion resistance of the material and changes in the electrical properties of the nanostructures formed to increase the potential application in flexible electronics. The molecular architecture (GPAH-PEI/GPSS-PAA)60 was characterized by Raman spectroscopy, contact angle measurements, atomic force microscopy, electrical measurements and nanoindentation. It was observed good self-healing capacity after 15 min f immersion in water at room temperature in a mechanical scratch of the order of 10 micrometers. It was also observed good hydrophobicity in the (GPAH-PEI/GPSS-PAA)60 LbL film ( teta = 136º) and atomic force microscopy and perfilometer indicate, respectively, surface roughness of 55 nm in a (2 ?m x 2 ?m) area and film thickness of 30 ?m. Raman analysis pointed out to a strong physical interaction between the rGO nanoplatelets with the polymeric materials, corroborating the strong insulating nature of (GPAH-PEI/GPSS-PAA)60 film that displayed a work function of 5.2 eV and electrical conductivity of 10-7 S/cm, which we believe results from the strong interactions of the nanosheets with the polymers. Finally, nanoindentation measurements indicated that the incorporation of GPAH and GPSS nanoplatelets increased hardness by 10 times, without compromising the regeneration
Mestrado
Física
Mestra em Física
1543078/2015
CAPES

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8

Cheviron, Perrine. "Nanostructuration de films nanocomposites amidon / argent et amidon / argent / montmorillonites par procédé de « chimie verte » : influence des voies de génération des nanoparticules métalliques sur la structure et les propriétés de transport." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10047/document.

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Des films nanocomposites amidon / argent ont été préparés par deux voies de génération vertes de nanoparticules d'argent. La première voie, dite ex situ, consiste à préparer tout d'abord une solution colloïdale d'argent qui est ensuite redispersée dans une matrice amidon plastifiée glycérol. Les nanoparticules d'argent colloïdales sont synthétisées en solution aqueuse par réduction du nitrate d'argent par du glucose en présence d'amidon stabilisant. La seconde voie, dite in situ, consiste à disperser le nitrate d'argent dans le film amidon plastifié et le réduire directement dans le film par traitement thermique en présence ou non de réducteur. L'influence du taux de glucose réducteur, du temps de synthèse et de la température a été étudiée en termes de taille, distribution de taille et dispersion des nanoparticules d'argent dans les films nanocomposites ex situ et in situ. Tout en gardant des paramètres de procédé comparables, les deux voies de nanostructuration des films amidon/argent ont également été comparées en termes de structure, de propriétés thermiques et de transport. Enfin, l'incorporation de charges montmorillonites a également été étudiée dans les deux voies de génération des nanoparticules métalliques. L'ensemble des travaux a permis de valider les deux voies de génération vertes menant à des nanoparticules d'argent dispersées de manière homogène et de tailles moyennes inférieures à 30 nm. La voie in situ à 85°C se distingue par des nanoparticules d'argent cristallines et de très petites tailles (inférieures à 10 nm) avec une interface amidon/argent cohésive particulière qui permettent d'améliorer les propriétés barrières aux gaz et à l'eau avec une diminution de perméabilité observée jusqu'à 90%
The present work reports a strategy involving the preparation of silver nanoparticles in a biodegradable polymer stemming from either an ex situ or an in situ method, using in both cases a completely green chemistry process. The influence of the reducing agent concentration and the silver nanoparticles generation route is investigated on the structure, the morphology and the properties of the nanocomposite films. In both routes, silver nanoparticles with a diameter below 30 nm were highlighted in the nanocomposite films. For all nanocomposite films, no modification on the crystalline structure of the starch matrix is observed in the presence of silver. The in situ generation route allowed to obtain the smallest silver nanoparticles with a diameter below 10 nm. Crystalline silver nanoparticles were obtained only from the in situ generation route at the temperature of 85°C. The introduction of montmorillonites in both generation routes was also studied. The decrease of the water sorption and the improvement of water and oxygen barrier properties were found to be not dependent on the reducing agent concentration but mainly on the presence of the crystalline structure of the silver nanoparticles. Thus, significant enhancement of the barrier properties were finally obtained for the in situ nanocomposite films thanks to an efficient interaction between the crystalline silver nanoparticles and the starch matrix

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Neella, Nagarjuna. "Development of Graphene Metal Nanocomposite Resistive Films for Flexible Sensors and Body Warmer Applications." Thesis, 2018. http://etd.iisc.ac.in/handle/2005/4263.

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Mankind’s desire is to replicate the nature’s creation provided an impetus and inspiration to the rapid advancements, especially progress made in the sensors and other devices for next generation technologies from nanoscience and engineering. Generally, human being has five basic sensory organs, which helps to perform routine tasks in normal life. This clearly signify the importance of basic sensory organs in a human life. In a similar way, sensors and other devices are very important for most of the scientific and engineering applications. The aim of the present thesis work is to explore the application possibilities of graphene and its derivative based films deposited on a flexible substrate for the development of sensors and other devices. Different types of flexible/rigid substrates such as Kapton, Cotton Cloth and Stainless Steel were chosen for different applications. Drop casting and Dip coating techniques were adopted for the deposition of graphene and its derivative based films onto the above-mentioned substrates. The necessary process parameters were optimized to achieve good quality films. To explore the applications in sensors and other devices have been developed by utilizing the direct transformation of graphene and its derivative nanomaterial-based films deposited on flexible/rigid substrates by above mentioned techniques. These devices include temperature sensor for measurement of environmental parameters, heating element devices on cotton cloth for wearable body warmer (in clod places). On the other hand, using piezoresistive effect of graphene and its derivative nanomaterial film strain gauges for force sensor have also been developed. This includes, a film nanomaterial of graphene and its derivatives was used for tensile test of force sensor/device, which work as a load cell. The present thesis work is divided into the following six chapters.

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Zhang, Kai Chun, and 張凱鈞. "Fabrication and Characterization of Graphene/Epoxy Nanocomposite Films." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/14076032421550644071.

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碩士
元智大學
機械工程學系
104
Graphene nanoplatelets (GNP) with excellent mechanical and thermal properties have been considered as ideal reinforcements. In this investigation, various contents of graphene nanoplatelets (MWCNT) ranging from 0.3 % ~1.0 % wt. were added to the epoxy to fabricate the nanocomposites. Nanocomposite films with thickness of 0.3 mm were deposited on the aluminum substrate using the spin coating. The Young’s modulus of the nanocomposite film was determined by the three-point bending test and nanoindentation test. The stress distribution and load carrying capability of the nanocomposite film subjected to tensile and bending loads were derived basing on the shear lag model and Bernoulli beam theory. Three-point and four-point bending tests were conducted to determine the interfacial fracture toughness of mode I and II, respectively. Experimental test results show that the Young’s modulus, load carrying capability and fracture toughness of the nanocomposite film are increasing with the increase of the content of GNPs In the case of nanocomposite film with 1.0 % wt. GNPs, the Young’s modulus, load carrying capability and fracture toughness are increased by 39%, 34% and 44% compared with neat epoxy, respectively. In addition, the dispersion of GNPs in the epoxy based matrix was examined using the scanning electronic microscope (SEM). The SEM images depict that GNPs are well dispersed resulting in the enhancement of the mechanical properties of the nanocomposite films.

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Huang, Siao-Yuan, and 黃孝源. "Biosensor based on graphene/nafion/horseradish peroxidase nanocomposite films." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/26498664472275109350.

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碩士
國立中興大學
化學工程學系所
102
This study successfully graphene/nafion/horseradish peroxidase nanocomposite film modified on glassy carbon electrode to prepared biosensor. By atomic force microscopy to observe the graphene / nafion/ horseradish peroxidase nanocomposite films is dispersed situations to cyclic voltammetry and amperometric detection.By cyclic voltammetry in 0.1M phosphate buffer solution (pH 7) to scan can observe the graphene / nafion/ horseradish peroxidase nanocomposite films of electrochemical reaction and in this experiments by different scan rates that confirmed this nanocomposite films is surface-controlled reactions.Reused amperometric observe the graphene / nafion/ horseradish peroxidase nanocomposite films nanocomposite films to detect the concentration of hydrogen peroxide, can get a sensitivity of 7.17x10-4(A/M-1cm2), detection limit of 15.63mM, the linear range of 30-120mM. From the experiments confirm this biosensor have been successfully to avoid interference of ascorbic acid 、 uric acid 、 glucose,and this nanocomposite films can be used to make specifically detection of hydrogen peroxide.

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Chen, Yi-Shiang, and 陳奕翔. "Preparation and characterization of MnOx/graphene oxide nanocomposite thin films." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/38751880443947495543.

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碩士
大同大學
材料工程學系(所)
101
This research mainly manganese oxide / graphene oxide as a composite material, the use of graphene oxide with high specific surface area in order to enhance the reaction of manganese oxide. Scan using SEM EDS mapping graphene oxide of manganese in the distribution of the surface, namely that the addition of potassium permanganate different weight ratio will be 125% coverage is wide. The XRD and EPR, respectively, adding that the high proportion of potassium permanganate is obtained when a larger proportion of manganese (IV) and capacitance value is higher. Add different weight ratios of carbon black with different weight ratios of potassium permanganate prepared electrode potentiostat (Jiehan 500 electrochemical workstation) for cyclic voltammetry tests find its capacitance value. The results showed that the addition of different weight ratio of 40% to 100% of carbon black and potassium permanganate test strip has a higher capacitance value 58.809 F / G.

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Li, Wei-Ting, and 李偉廷. "Silver Nanoparticle/Boron-doped Graphene Nanoribbon Nanocomposite for Effective Surface Enhanced Raman Scattering." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/17210541373657573312.

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碩士
國立臺灣科技大學
化學工程系
105
Surface-enhanced Raman scattering (SERS) provides high sensitivity and selectivity on molecule detection, making it attractive for biomedical and chemical detections. Generally there are two mechanisms to influence the SERS enhancement: electromagnetic mechanism (EM) created by the metals with surface plasmon resonance (SPR) property and chemical mechanism (CM) caused by several possible aspects. The development of synthetic method to produce nanostructures with controllable EM and CM properties will lead to important advances on both fundamental study and innovative applications for SERS-based biomedical detections. Graphene nanoribbons (GNRs) represent a unique structure of carbon nanomaterials with controlled electronic properties by tuning their widths, making them can be potentially useful as the SERS-active substrate and used in other applications including energy, composites, biomedical and electronics. Here we report a rational design to develop a SERS-active nanocomposite with improved EM and CM properties. Toward this goal, we prepared silver nanoparticle (AgNP)/Boron-doped GNR (B-GNR) composites using a sequential reaction route. First we synthesized GNRs with averaged width around 4 to 5 nm by chemical unzipping the singled-walled carbon nanotubes (SWCNTs). Additionally, the prepared GNRs were doped with B atoms by a controlled carbonthemic reaction under argon (Ar) flow at atmospheric pressure and the B dopant concentration was about 1.4 atomic percentage (atom%) according to the X-ray photoelectron spectroscopy (XPS) analysis. Ag NPs with 10 nm averaged size were decorated onto the B-GNRs surface through an atmospheric-pressure microplasma-assisted redox reaction. Detailed materials characterizations including transmission electron microscopy and UV-Vis spectroscopy show that Ag/B-GNR composites were successfully synthesized in our experiment. We further systematically studied the Raman response of the AgNP/B-GNR composite using Rhodamine 6G (R6G) as the Raman probe molecules. The result indicates that the AgNP/GNR composite shows superior SERS performance with low detection concentration of 10-12 M of R6G and high enhancement factor (EF) of 1.9×1012. We further systematically studied the CM enhancement via different probing molecules and substrates. Results show that SERS performance is strongly influenced by the laser alignment resonance effect and the substrate surface adsorption ability. To demonstrate the feasibility of using AgNP/B-GNR as the SERS substrate for detecting the folic acid (FA) molecule, we perform a series of SERS measurements under different FA concentrations. The result indicated that the as-produced nanohybrid can reach 10 nanomolar-level detection. Overall, our study provide the conception to design the applicable SERS substrates.

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Fang, Guo-Cyuan, and 方國權. "Graphene/Cyclic Olefin Copolymer Nanocomposite Films as High-Performance Moisture Barriers." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/u66dby.

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碩士
國立臺灣大學
材料科學與工程學研究所
106
Gas barrier has gained much attention in recent year, it dominates a variety of application ranging from food industry to electronic devices as a means of preventing them from moisture and dust to extend the life-time of perishable goods and electronic devices. Graphene is the strongest and thinnest material ever known with ultra-large aspect ratio, and therefore it has been shown to yield greatly enhanced mechanical properties in graphene/polymer nanocomposites. Moreover, it has also been shown that graphene is impermeable to oxygen, water and even helium. The dispersion of graphene elongates the diffusion path of water molecules and thus improves water vapor barrier property. This promises the realization of gas barriers from graphene/polymer nanocomposites, as long as pristine graphene can be uniformly and orderly dispersed in the polymer matrix. However, the strong π-π interactions between pristine graphene sheets make them difficult to disperse in most media, thereby greatly limiting the gas-barrier performance of graphene/polymer nanocomposites. In this study, by systematically testing solvents with various surface properties (including surface energy and Hansen solubility parameter and conditions of the solution blending process. We successfully dispersed pristine graphene uniformly in cyclic olefin copolymer (COC). The result of COC/graphene nanocomposite exhibited low water vapor permeability (0.00276 g·mm/m^2·day·atm) and interesting thermo-mechanical properties.

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15

Chang, Chin-Wen, and 張謹文. "Moisture Barrier and Anticorrosion Properties of Polyimide/Graphene Oxide and Poly(amide-imide)/Graphene Oxide Nanocomposite Films." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/00669101768888879373.

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碩士
國立勤益科技大學
化工與材料工程系
101
The main studies of this dissertation are divided into two parts: (1) preparation and appraisal of the Graphene Oxide (GO)；(2) synthesize and characterize of the Polyimide/Graphene Oxide (PI/GO) and Poly(amide-imide)/Graphene Oxide (PAI/GO) nanocomposite films. The Graphene Oxide (GO) can be produced by the Hummer’s method and through exfoliation at high temperature by strong oxidizers Potassium Permanganate (KMnO4)、Sodium Nitrate (NaNO3) and Sulfuric acid (H2SO4) solution. Besides, the composite films are synthesized from 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), trimellitic anhydride chloride (TMAC) and 4,4'-oxydianiline (ODA) via polymerization method,which change molar ratio of anhydride monomer TMAC and BTDA, the contents of GO, and then a series of composite films characteristic analysis. The nanostructure of GO is characterized with X-ray diffraction spectrometer (XRD), Raman spectrometry, Fourier transform infrared spectroscopy (FTIR) and High-resolution electron spectrometer (XPS). The graphite has been successfully oxidation by heavily oxygenated compounds bear carboxylic acid groups (carboxylic acid groups,-COOH) and hydroxyl group (hydroxide groups,-OH). The TEM micrographs could be also observed that the dispersion extent of PI-1-TMAC/10 is better than PI-0.5-TMAC/10 nanocomposites and PI/10. As for the results, the reason should be ascribed to increase of TMAC content will enhance the intermolecular attraction of GO. From the dynamic mechanical analysis (DMA), it is indicated that the storage modulus of PI/GO and PAI/GO nanocomposite films series can be achieved up to 3152.4 MPa、tanδ is reduced to 0.15 and the glass transition temperature (Tg) is over 297℃ when GO content is within 20 wt%. The thermogravimetric analysis (TGA) shows the 5% weight loss of hybrid film is around 473℃. The water vapor transmission rate (WVTR) of series of PI-1-TMAC/GO films are the lowest one compared with series of PI-0.5-TMAC/GO and PI/GO films, respectively. A significant decrease in WVTR by 92.7%, from 65.15 to 4.75 g-m/m2-day, was observed upon the addition of 10 wt% of GO in PI-1-TMAC matrix. The the strong interfacial adhesion between GO and PI-1-TMAC matrix, distribution of GO with the features of high aspect ratio and high speciﬁc surface area in PI-1-TMAC matrix could effectively extend the path of the water vapor passing through the thin ﬁlm, thus signiﬁcantly improved water vapor barrier property. In electrochemical corrosion measurements of PI/GO and PAI/GO nanocomposites. The CRS coated with PI/5 and PAI/5 shows the best anti-corrosion than those coated with pure PI, PAI and uncoated CRS. Especially, PI/5-coated CRS electrode exhibited a high the corrosion inhibition efﬁciency (ηp) of 97.4 %, but the effect of preservative is greatly reduced when GO content is within 10 wt%. Furthermore, through high resistance measurement, surface resistivity of the PI-1-TMAC/10 composite film can be reduced to 5.39 × 108 Ω, therefore a bridging the flow or through of electrons formed increases in the structure, thereby reducing the effect of anticorrosion. However, comparing PI / GO and PAI / GO series composite films of anti-corrosion data, this results was opposite to the WVTR, we thought that poor anti-voltage of the N-H functional group in PAI, therefore prone to degradation in the electrochemical reaction.

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16

Yang, You-Hao. "Processing and Gas Barrier Behavior of Multilayer Thin Nanocomposite Films." Thesis, 2012. http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11685.

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Thin films with the ability to impart oxygen and other types of gas barrier are crucial to commercial packaging applications. Commodity polymers, such as polyethylene (PE), polycarbonate (PC) and polyethylene terephthalate (PET), have insufficient barrier for goods requiring long shelf life. Current gas barrier technologies like plasma-enhanced vapor deposition (PECVD) often create high barrier metal oxide films, which are prone to cracking when flexed. Bulk composites composed of polymer and impermeable nanoparticles show improved barrier, but particle aggregation limits their practical utility for applications requiring high barrier and transparency. Layer-by-layer (LbL) assemblies allow polymers and nanoparticles to be mixed with high particle loadings, creating super gas barrier thin films on substrates normally exhibiting high gas permeability. Branched polyethylenimine (PEI) and poly (acrylic acid) (PAA) were deposited using LbL to create gas barrier films with varying pH combinations. Film thickness and mass fraction of each component was controlled by their combined charge. With lower charge density (PEI at pH 10 and PAA at pH 4), PEI/PAA assemblies exhibit the best oxygen barrier relative to other pH combinations. An 8 BL PEI/PAA film, with a thickness of 451 nm, has an oxygen permeability lower than 4.8 x 10^-21 cm^3 * cm/cm^2 * s * Pa, which is comparable to a 100 nm SiOx nanocoating. Crosslinking these films with glutaraldehyde (GA), 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide methiodide (EDC) or heating forms covalent bonds between PEI and/or PAA. Oxygen transmission rates (OTR) of 8 BL films crosslinked with 0.1M GA or 0.01M EDC show the best oxygen barrier at 100% RH. Graphene oxide (GO) sheets and PEI were deposited via LbL with varying GO concentration. The resulting thin films have an average bilayer thickness from 4.3 to 5.0 nm and a GO mass fraction from 88 to 91wt%. Transmission electron microscopy and atomic force microscopy images reveal a highly-oriented nanobrick wall structure. A 10 BL PEI/GO film that is 91 nm thick, made with a 0.2 wt% GO suspension, exhibits an oxygen permeability of 2.5 x 10^-20 cm^3 * cm/cm^2 * s * Pa. Finally, the influence of deposition time on thin film assembly was examined by depositing montmorillonite (MMT) or laponite (LAP) clays paired with PEI. Film growth and microstructure suggests that smaller aspect ratio LAP clay is more dip-time dependent than MMT and larger aspect ratio MMT has better oxygen barrier. A 30 BL PEI/MMT film made with 10 second dips in PEI has the same undetectable OTR as a film with 5 minute dips (with dips in MMT held at 5 minutes in both cases), indicating LbL gas barrier can be made more quickly than initially thought. These high barrier recipes, with simple and efficient processing conditions, are good candidates for a variety of packaging applications.

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17

Wu, Wei-chi, and 吳唯齊. "Synthesis of Silver Nanowires for Transparent Conductive Films and Graphene-based Supercapacitors." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/12685455566241226154.

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碩士
國立臺南大學
材料科學系碩士班
101
In recently, the 3C technology is developing very fast. Therefore the performance of energy storage dvice (such as batteries and capacitors) and conductivity of the conductive film is extremely important in the development of products. The study of supercapacitors at the present time is foucused on improving the performance of electrode material. Carbon-based materials seem to play an important role in the development of electrochemical device. At present the most common material in the transparent conductive films is the tin doped indium oxide (ITO). Silver nanowire films emerge as a promising material for transparent conductive films in recent years. Silver nanowires have excellent electrical and thermal properties, and it also has a good ductility. Therefore, silver nanowires are attracting great attention in the field of transparent conductive films. Therefore, this paper is divided into two parts, i.e., the synthesis of silver nanowire and conductive thin films, and their applications in grapheme-based supercapacitors. However, we try to add the silver nanowire to the supercapacitors to promote their performance. In the synthesis of silver nanowire, we prepared silver nanowires by the polyol synthesis, with an aim to prepare silver nanowires in a more efficient scheme. For, we tried to use different precursors for seeds to make silver nanowires, and we added potassium bromine to decrease the diameter of silver nanowire in several reaction systems. Finally, we used the silver nanowires to make conductive films by spin coating. SEM and UV-Vis spectra have been employed to characterize the silver nanowires. We successfully prepared the films of silver nanowires with a transparency of 69.7 ％ and a sheet resistance of 95.4 Ω/sq. In the part of graphene supercapacitors, the Hummer’s method is used to prepare the graphite oxide, and hydrazine is used to obtain reduced graphene oxide solution. In the experiment, first we prepared the supercapacitors with both graphene oxide and reduced graphene oxide. Then we changed the composition of electrolyte in the supercapacitor device, and tried to add ZnO nanoparticles into the supercapacitors to improve their capacitance. Electrochemical workstation and UV-Vis spectra have been employed to characterize the graphene supercapacitors. Finally, We obtained transprant soildstate graphene supercapacitors with a transparency of 83.7 ％ and a capacitance of 617 F/g in this study. In the end of this thesis, we tried to add the silver nanoparticles and nanowires into supercapacitors in order to improve the conductivity and capacitance of supercapacitor. We obtain the transprant soildstate supercapacitors with a transparency of 88.6 ％ and a capacitance of 562.6 F/g in this study.

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18

Tsai, Yu-Wei, and 蔡育維. "Preparation and Properties of Silver-filled Multi-Wall Carbon Nanotubes / Poly (amide-imide) Nanocomposite Films." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/07923352321410178879.

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碩士
國立勤益科技大學
化工與材料工程系
97
This study was mainly focused on the acid pre-treatment of Multi-wall Carbon Nanotube (MWCNT) and the synthesis of the hybrid film. The opening and purification of Multi-wall Carbon Nanotube was acquired from the acid pre-treatment by applying sulfuric and nitric acid solution. Through the capillary phenomenon, the Ag particles were inserted during the purification process. After sintering at high temperature, the Ag-filled multi-wall carbon nanotubes were obtained. Besides, the hybrid film is synthesized from 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 4,4'-oxydianiline (ODA) and trimellitic anhydride chloride (TMAC) via polymerization method. The nanostructure of MWCNT is characterized with field-emission scanning electron microscope (FESEM), Raman spectrometry and Fourier transform infrared spectroscopy (FTIR). The morphology of Ag-filled MWCNT was investigated with High-Resolution Transmission Electron Microscopy (HR-TEM) and Energy Dispersive Spectrometer (EDS). For the hybrid film, the degree of polycondensation was successfully identified with Fourier transform infrared spectroscopy (FTIR). From the dynamic mechanical analysis (DMA), it is indicated that the storage modulus of PAI/Ag-CNT-X series can be achieved up to 3152.4 MPa and the glass transition temperature (Tg) is over 280℃ when Ag content is within 2.5 wt.%. The thermogravimetric analysis (TGA) shows the 5% weight loss of hybrid film is around 520℃. Furthermore, the surface resistivity of 1.5 wt.% Ag-MWCNT hybrid film could be drastically decreased and kept at 109 Ω. As compared to pure-PAI, the thermal conductivity of 1.5 wt.% Ag-MWCNT hybrid film can be increased by 62.7 % and the value is up to 0.135 W/mK.

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19

Chiang, Jen-Chi, and 江仁吉. "Study on the Preparation of Multi-Walled Carbon Nanotubes/Boron Nitride/Graphene/Polyimide Nanocomposite Films." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/63441507421055626059.

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碩士
國立勤益科技大學
化工與材料工程系
100
This paper aims to explore the multi-walled carbon nanotubes (CNT) and the functional groups of carbon nanotubes (m-CNT,g-CNT) and boron nitride (BN), graphene (TrG) and surface modification of graphene Preparation and thermal properties of the polyimide (Polyimide, PI) composite films. Part I: Preparation of polyimide /carbon nanotube composite thin films and ResearchIn this study, successful use of free radical polymerization (free in radical polymerization) methacrylamide MAM and glycidyl methacrylate GMA covalent bonding grafted CNT surface, the system of functional groups of carbon nanotubes to explore its Poly amide formation of the thermal conductivity of the composite thin film properties and related characteristics of Experimental results show that the Raman analytical grade carbon nanotubes D / G band integral area ratio of 1.08. Respectively, grafted onto the carbon nanotubes of the MAM and the GMA D / G band integral area ratio of 1.10 and 1.15, indicating that its addition can be effectively modified carbon nanotubes, but also to maintain the structural integrity of the carbon nanotubes. SEM patterns, the study found that the functional groups of carbon nanotubes have better dispersion than the unmodified carbon nanotubes. Functional groups of carbon nanotubes (g-CNT)) / polyimide composite films show the most outstanding thermal conductivity (the thermal conductivity, k) 0.13W/mK (pure polyimide) increased to 0.44W/mK (2wt%g-CNT), 238% increase. Part II: Preparation of polyimide / boron nitride composite films and ResearchIn this study the traditional, high heat resistant polyimide monomer combination of changes in the mechanical and thermal properties of boron nitride in a polyimide composite films made of the analysis to add different size combinations of unmodified, and further compare Add a titanium coupling agent (2 - ((2-aminoethyl) amino) ethoxy) (isopropoxy) titanium) modification of boron nitride (Ti-BN) influence. The results show that adding 50wt% in two different BN particle size (4m and 15m) polyimide composite membranes, will be able to achieve a very low coefficient of thermal expansion (coefficient of the thermal expansion, the CTE, 14 ppm/oC ) and the high value of k 0.75W/mK, BN particle combinations if more contained in the composite membrane after modification, may be even lower CTE (12 ppm / oC) and higher values of k ( 0.86 W / mK), the increase in force between the PI and modified BN composite film has excellent dimensional stability and thermal conductivity, the composite membrane with sufficient mechanical strength and heat resistance. Part III: Preparation and study of the polyimide / graphene composite filmsChemical to restore the rule of law prepared by graphite-ene (Graphene) required by the oxidation of natural graphite (Graphite), in order to reduce between graphite layers where have Waal forces, preparation of oxidation of graphite ene (Graphene Oxide, GO), by heat restore Prepared graphene to explore the preparation and identification of graphene, and functional groups of grafted GMA graphene oxide and graphene surface, can contribute to the compatibility between Graphene and polyimide film, the more uniform graphene dispersed in the polyimide, the results show that in addition with 10wt% graphite oxide-ene (GO) k value 0.3W/mK functionalization of graphene oxide (g-GO) k enhance the value of 523 % (0.81W/mK). But restored graphene add the amount of 2wt%, graphene (TrG) k is the the 0.35W/mK functionalization of graphene (g-TrG) and k enhance the value of 300% (0.52W/mK); compared to add the same content of the modified carbon nanotubes (g-TrG) and about 25% higher. Show modified graphene increase the PI thermal conductivity between the network closer to increase the thermal conductivity to reduce the interface thermal group. Part IV: polyimide / carbon nanotube / boron nitride / graphene hybrid filmsThe fourth part of this study is to explore the blended filler formula (hybrid filler) in the optimal thermal conductivity in polyimide hybrid films. Blended filler filler boron nitride (sheet), high aspect ratio and high fever - borne one-dimensional structure of carbon nanotubes (tubular) and large surface area of the base and high heat transfer nature two-dimensional structure of graphite ene (flake), supplemented by the effective thermal conductivity of the network structure in the case of low add content. One-dimensional carbon nanotubes and two-dimensional graphene and boron nitride (4 m and 15m) between the filler Association into effect in the system. The results showed that the boron nitride surface with a better dispersion of the titanium coupling agent modified polyimide composite film. To Add 10wt% of functional groups of boron nitride with 1wt% of functional groups of carbon nanotube thermal conductivity of about 1.26W/mK, its thermal conductivity is greater than the addition of 50wt% modification of boron nitride / polyimide amine system (0.86W / mK), the composite formula can replace a single BN formula; about 1.41W/mK add 10wt% functionalization of boron nitride with 1wt% functionalization of graphene thermal conductivity, thermal conductivity greater than the functional groups of carbon nanotube / functional boron nitride / polyimide thin-film systems above 12 percent, the highest values of k up to 2.11W/mK composite film can reduce costs and enhance the workability of the PI.

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20

Lai, Yi-Ting, and 賴怡廷. "High performance flexible transparent conductive films based on reduced graphene oxides and silver nanowires." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/19964776613070757817.

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碩士
國立清華大學
材料科學工程學系
102
This work demonstrates an one-step process to synthesize uniformly dispersed hybrid nanomaterial containing silver nanowires (AgNWs) and p-type reduced graphene (p-rGO). The hybrid nanomaterial was coated onto a polyethylene terephthalate (PET) substrate to prepare high performance flexible transparent conductive films (TCFs). The p-rGO plays the role of bridging discrete AgNWs, providing more electron holes, and lowering the resistance of the contacted AgNWs, which enhances the electrical conductivity without sacrificing too much transparence of the TCFs. In addition, the p-rGO also improves the adhesion between AgNWs and substrate by covering the AgNWs on substrate tightly. The study shows that coating of the hybrid nanomaterials on the PET substrate demonstrates exceptional optoelectronic properties with a transmittance of 94.68% (at a wavelength of 550 nm) and a sheet resistance of 25.0 ohm/sq. Furthermore, no significant variation in electric resistance can be detected even though the film was subjected to a bend loading with a radius of curvature of 5.0 mm or the film was loaded with a reciprocal tension or compression for 1000 cycles. The study shows that the fabricated flexible TCFs have the potential to replace indium tin oxide film in the optoelectronic industry.

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21

Chen, Hsiang Hung, and 陳相宏. "Preparing Graphene/Silver nanowires/ Polyvinyl alcohol complex thin films for Electromagnetic Interference Shielding Application." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/35608660030997527555.

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碩士
國立清華大學
化學工程學系
103
As electronic devices become popular in the application of military, industrial, communications, biomedical, and in space, some noise pollution, radio frequency interference (RFI), radio radiation, electromagnetic interference (EMI) problems are more serious. These problems will not only interfere with equipment but damage to human health. Therefore, in order to prevent these disturbances become more serious, developed with technology or electromagnetic shielding material is very important. This study wishing graphene as an electrically conductive filler, blended with water soluble polyvinyl alcohol. We make use of the good film-forming properties of polyvinyl alcohol, to prepared a composite film with electromagnetic shielding properties. This process does not use organic solvent, in line with concept of environmental protection. Furthermore, in order to achieve good graphene dispersion in polyvinyl alcohol substrate, we using dispersant to disperse graphene to achieve a better degree of conductivity, and have better electromagnetic shielding effects. On the other hand, silver nanowires have well conductivity and good stability. Therefore, in order to build a better electrically conductive network, this study added silver nanowires as second filler material. We also used glutaraldehyde to crosslink PVA to enhance the water resistance of composite. Finally, at ASTM-D4935-99 test specification, using vector network analyzer to detect the electromagnetic shielding effect of composite film to give a electromagnetic shielding effect, excellent workability, and nontoxic PVA / graphene / silver nanowires composite film.

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22

Qiu, Tai-jie, and 邱泰傑. "Synthesis and Characteristics of Silver Nanowires and Reduced Graphene Oxide for Transparent Conductive Films." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/76937535086318555447.

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碩士
國立臺南大學
材料科學系碩士班
99
At present the most common material in the transparent conductive films is the tin doped indium oxide (ITO), because ITO has the high transmittance as well as good electrical property. However, ITO has certain problems, mainly centered on its scarcity of supply. Researchers have tried to develop new transparent conductive materials to replace ITO, such as carbon nanotube, graphene, and silver nanowires. In our study, the aim is to prepare and evaluate the films of silver nanowires, graphene, and their mixtures for the application as transparent conductive films. This paper will be divided into two major parts: the synthesis of silver nanowires, graphene and their hybrid materials, and the preparation and characterization of transparent conductive thin films both on the glass and flexible substrates. First, we used the polyol method to synthesize silver nanowire with sodium chloride (NaCl) as the precursor for seeds. The experimental results show that the different seeds used, the concentration of reactants, and the addition rate of silver nitrate will affect the growth characteristics of silver nanowires. SEM, UV-vis spectra and XRD have been employed to characterize the silver nanowires. This study successfully prepared silver nanowires with a diameter of 100 nm and a length of 17 μm, and the films prepared using the nanowires can have a transparency of 83 % and a sheet resistance of 11 Ω/sq. Next, the Hummer’s method is used to prepare the graphite oxide, and hydrazine is used to obtain reduced graphene oxide solution. We further varied the solid concentration and deposition density to prepare graphene thin films, and then improved the conductivity of thin films by a heat treatment step. We obtain graphene films with a transparency of 80 % and a sheet resistance of 90 kΩ/sq. And then, we mixed the silver nanowire and graphene suspensions to form hybrid materials with different ratios. The obtained films show a transmittance of 77.6 %and a sheet resistance of 17.8 Ω/sq. Finally, this study further used polyvinyl alcohol(PVA), polyamide acid(PAA) and polydimethyl siloxane(PDMS) as substrates to prepare flexible transparent conductive films. The hybrid thin films prepared on the PVA flexible substrates can have a transparency of 78.2 % and a sheet resistance of 18.8 Ω/sq.

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23

XIAO, PU-JIN, and 蕭譜晉. "Optical and electrical properties of silver nanoparticles/graphene conductive films with different polyethylene glycol concentrations." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/88dc2n.

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碩士
國立高雄科技大學
機械工程系
107
In this research, the electronic and optical properties of glasses spin-coated with graphene solution added with different concentration of silver nanoparticles and Polyethylene glycol as dispersant. At first, Taguchi technique is used. Silver nanoparticle concentration, polyethylene glycol concentration, ethanol concentration, spin speed, time of coating, processing temperature, and time of heating are chosen as control factors. In this step, four greater influential factors are picked as control factors for second step. Secondly, Silver nanoparticle concentration, polyethylene glycol concentration, ethanol concentration, spin speed are chosen as control factors to calculate optimized parameters. A confirmation experiment is conducted with optimized parameters to verify the correction of Taguchi technique. The optical properties, resistance, surface morphologies, and element on the surface of TCEs were characterized. The influences of different concentration Polyethylene glycol to optical and electrical properties of solution-processed electrodes was investigated. The result shows that TCEs Processed with optimized parameters of 1%wt silver nanoparticle concentration, 3ml polyethylene glycol concentration, 10ml ethanol concentration, and 500rpm spin speed, exhibited 316Ω resistance with ~98% transparency.

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24

HUANG, YI-WEI, and 黃益偉. "The Study of Characteristics About Polyvinyl Alcohol-Silver Nitrate Conductive Films Adding Multi-Layer Graphene." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/684vt3.

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碩士
國立雲林科技大學
環境與安全衛生工程系
106
This study is produced environmental, flexible conductive film by polyvinyl alcohol with characteristics that has malleable, can be widely decomposed by microorganisms. Then silver nitrate is reduced by the functional groups rich in polyvinyl alcohol to form conductive silver nanoparticles. Finally, a multi-layered graphene is added to the conductive film in a physically mixed manner, and the graphene surface is rich in positive electricity, which helps the silver particles form a silver floe. Preparation of conductive film samples with different ratios of silver nitrate and multilayer graphene, and make a treatment with heat. And through a variety of instrument detection include: Field emission scanning microscope (FE-SEM), UV-VIS spectrometer (UV-VIS), Fourier transform infrared spectrometer (FT-IR), X-ray diffraction analyzer (XRD), heat Heavy loss analyzer (TGA) and four-point probes were used to compare the differences in surface characteristics, transmittance, characteristic functional groups, crystal structure, thermal stability, and conductivity between the samples. This study concluded that the addition of silver nitrate and multilayer graphene will cause the transmittance of the conductive film to decrease, but increasing the amount of silver nitrate and multilayer graphene can increase the conductivity of the conductive film. It was found from the TGA analysis that the addition of silver nitrate resulted in a decrease in the thermal stability of the polyvinyl alcohol, which could be improved by the addition of multilayer graphene.

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25

Hung, Yu-Heng, and 洪彧珩. "Preparation of Superhydrophobic Surface, High Conductivity and Intelligent Senor for Carbon Black/ Graphene / Polyurethane Nanocomposite Films by Electrospinning." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/6w8x79.

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碩士
國立臺灣科技大學
材料科學與工程系
105
The main purpose of this study is to prepare for making polyurethane (PU) nanofiber film by electrospinning method. The fiber membrane with high specific surface area can be obtained in the process. PU is an insulating polymer material and therefore we use different dimensions of carbon materials to modify surface and blend them into fiber. The formation of conductive polymer fiber film is used in the sensor components to measure body signals. This study is divided into two parts. The first part is the preparation of polyurethane nanofiber thin film by electrospinning method. The surface is coated solution using star oil-soluble polymer dispersant dispersed carbon black (Carbon Black, CB), Graphene in toluene. We put the fiber film into dispersed CB/PML solution, and then the micron / nano dispersion and aggregation phenomenon can mimic the structure of the lotus leaf surface to improve the roughness and hydrophobicity of the film surface. In addition, it can increase electrical conductivity through the carbon materials. In the second part, the carbon nanofiber film is prepared by electrospinning. The carbon black solution dispersed with the dispersant is mixed into the low concentration of PU, and directly form the conductive Polymer film. It thereby is compared with the conductive film formed by surface coating in terms of conductivity, hydrophobicity and its mechanical and thermal properties. The experimental results show that the hydrophobic angle of the film can reach more than 150 degrees, while the surface resistance is less than 1,000 ohms. This film not only has flexibility of the PU and is also very light. Therefore, it can be successfully used in human sensing electrode materials owing to the change to its feature of insulation. Furthermore, it can be applied to the smart clothes using electrocardiogram to measure body signals.

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26

MonsaludEbuen, Anna Sophia, and 游安純. "Study of Piezo-related and Photoelectrochemical Properties of Pristine Bi4Ti3O12 and Bi4Ti3O12-Reduced Graphene Oxide Nanocomposite Thin Films." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/w9az4m.

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碩士
國立成功大學
材料科學及工程學系
106
Bi4Ti3O12 films and Bi4Ti3O12/rGO composites on FTO substrates were fabricated using a facile sol-gel method and were investigated regarding its piezo-related capabilities, photocatalysis, and PEC properties. UV-illumination and a hydrothermal approach were employed to reduce GO to rGO, which was ascertained through XRD, Raman and XPS. The bonding between Bi4Ti3O12 and rGO was also ascertained through XPS because of the presence of the Ti-O-C peak on the samples of Bi4Ti3O12/rGO (UV) and Bi4Ti3O12/rGO (hydro). The piezo-related studies of the pristine Bi4Ti3O12, Bi4Ti3O12/rGO (UV), and Bi4Ti3O12/rGO (hydro) indicated minor piezotronic and piezophototronic effects, which was attributed to poor inducement of piezopotential because of random distribution of Bi4Ti3O12 crystals instead of well aligned morphology. However, the photocatalytic and piezophotocatalytic properties of the samples were promising, wherein Bi4Ti3O12/rGO (hydro) sample exhibited the best performance with k of approximately 24  10-3/min-1, which was 4~5 times higher than that of the pristine Bi4Ti3O12. In addition, the excellent photoelectrochemical performance of composite samples was preliminarily determined from the observation of an enhancement in its photocurrent density under visible light illumination. The photocatalytic properties were consistent with the deduced energy band diagram, which showed that a more negative conduction band positions than the formation potential of superoxide radicals (O2/•O2-) was ideal for photodegradation applications, and that the conduction and valence band edge potentials straddled the hydrogen and oxygen redox potentials was excellent for overall photoelectrochemical water splitting.

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27

Liu, Bo-Cheng, and 劉柏成. "Preparation and Optoelectronic Properties of Transparent Conductive Hybrid Films Based on Reduced Graphene Oxide Conjugated with Silver Nanowires." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/rnqed2.

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碩士
國立高雄應用科技大學
化學工程與材料工程系博碩士班
105
In this study, transparent conductive hybrid films (TCFs) based on reduced graphene oxide (rGO) conjugated with silver nanowires (Ag NWs) were fabricated by spin coating method and thermal treatment. Various feature parameters (i.e., line length (L), line diameter (D) and the aspect ratio (L/D)) of Ag NWs were synthesized by polyol process. Ag NW-rGO composites were further prepared by combined Ag NWs with rGO in one-step process, where rGO was prepared by modified Hummers method. Effects of reaction conditions of polyol process (i.e., stirring speed, feed rate and PVP concentration), purification methods (i.e., traditional centrifugal and selective precipitation method) and rGO layer on the feature parameters, conducting networks, sheet resistance and transmittance of Ag NW-rGO TCFs are characterized. Results showed that, at appropriate reaction conditions of polyol process, the synthesized Ag NWs exhibits the average line length (Lavg.) is 5.8 μm, the line diameter (Davg.) is 112 nm and the aspect ratio ((L/D)avg.) is 51.8. As compared with the traditional centrifugal method, the selective precipitation method provides the most of non-conductive PVP layer, which on the surface of Ag NWs, and the growing incomplete Ag NPs can be effectively removed. The reduction of the electron transfer resistance and light scattering phenomenon can be achieved by the removal of Ag NPs. The structural defects of Ag NWs networks which caused by uneven dispersion can be improved by the Ag NW-rGO conductive composites. At coating quantities 150 μL, Ag NW-rGO TCF exhibits the best optoelectronic properties, the sheet resistance is 167 Ω/sq and transmittance is 50% (at 550 nm). The optoelectronic properties of Ag NW-rGO TCF are markedly affected by their morphology and structure of Ag NW-rGO conductive networks.

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28

Peng, Shih-Liang, and 彭士樑. "WO3 / reduced graphene oxide nanocomposite films were fabricated by combining one-pot polyol process with metal organic decomposition method for NO2 sensing at room-temperature." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/s98t2w.

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碩士
中國文化大學
化學系應用化學碩士班
103
One-pot polyol process was combined with metal organic decomposition (MOD) method to fabricate a room-temperature NO2 gas sensor based on tungsten oxide and reduced graphene oxide (WO3/RGO) nanocomposite films. X-ray diffractometry (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the structure and morphology of the fabricated films. Comparative gas sensing results indicated that the sensor that was based on the WO3/RGO nanocomposite film had much more response than that based on pure WO3 film in detecting NO2 gas at room temperature. Microstructural observations revealed that RGO was embedded in the WO3 matrix. Therefore, a model of potential barriers to electronic conduction in the composite material was used to reveal that the high response was associated with the stretching of the two depletion layers at the surface of the WO3 film and at the interface between the WO3 film and the RGO when detected gases are adsorbed at room temperature. The sensor that was based on a nanocomposite film of WO3/RGO responded strongly to low concentrations of NO2 gas at room temperature and its use is practical because of it is easy to fabricate.

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29

CHIANG, PIN-HSUAN, and 江品璇. "Preparation and Optoelectric Properties of Few-Layer Reduced Graphene Oxide Conjugated with Self Welding Silver Nanowire Junctions as Flexible Transparent Conducting Hybrid Films." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/m676a4.

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碩士
國立高雄應用科技大學
化學工程與材料工程系博碩士班
106
In this study, flexible transparent conducting hybrid films (TCFs) based on few layer reduced graphene oxide (FrGO) conjugated with hydrolyzed-polyethylene terephthalate (H-PET)-based self-welding (SW) commercial silver nanowires (AgNWs) were fabricated by water-bath assisted dipping coating method. H-PET-based SW-AgNW networks were controlled by the mirror silver reaction with different reaction rates and followed by dip-coated on the H-PET film. Few layer graphene oxide (FGO) were prepared by modified Hummers and low speed centrifuge method. FrGO/SW-AgNW TCFs were further prepared by reduced under sodium borohydride and followed by dip-coated on the H-PET-based SW- AgNWs. Effects of mirror silver reaction rate and FrGO layer on the conducting networks, surface morphology, sheet resistance and transmittance of FrGO/SW-AgNW TCFs are systematically studied. The interaction between AgNWs and FrGO was also further discussed. Results showed that SW-AgNW TCFs can be successfully prepared by water-bath assisted dip-coated and mirror silver reaction. As for optical and electrical characteristics analysis, the gain value of transmittance (GPS) can reach 1.88% (the transmittance is slightly increased from 76.06% to 77.49% ) which induced by the self-welding effect. However, GPS value is decreased with increasing the mirror silver reaction temperature and time. The Gain values of sheet resistance (GES) exhibit mostly negative in nature, the maximum value of GES can remark reduce to 61.06%, confirm the truth of mirror silver reaction with the excellent self-welding effect, as well GES value is also decreased with decreasing the mirror silver reaction temperature and time. Furthermore, the results revealed that FrGO/SW-AgNW TCFs can be successfully prepared by water-bath assisted dip-coated. As for optical and electrical analysis, the gain value of transmittance (GPF) can reach 1.92% (the transmittance is slightly increased from 70.80% to 72.16%). The gain value of sheet resistance (GEF) can remark reduce to 59.9% (the sheet resistance dramatically dropped from 123.6 Ω/sq to 49.5 Ω/sq). For Raman and XPS analysis, the charge transfer behavior between FrGO and SW-AgNWs is observed, which attributed to the bridging effect between FrGO and SW-AgNWs, leading to the increase the number of conductive paths in the networks.

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30

(8085995), Tahrima Binte Rouf. "Design and Mechanistic Understanding of Zein Nanocomposite Films and Their Implementation in an Amperometric Biosensor for Detection of Gliadin." Thesis, 2019.

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Zein is a major storage protein of corn, with unique amphiphilic film forming properties. It is insoluble in water, but soluble in 70% ethanol and acetic acid, and has been declared ‘generally recognized as safe’ (GRAS) by the FDA. Due to new advances in food nanotechnology, zein is being investigated for various applications such as biodegradable packaging, oral delivery of proteins and peptides, scaffold for tissue engineering, as well as biodegradable sensor platforms. The time consuming and highly complicated methods for toxin and allergen analysis in the food industry necessitates the need for a rapid, selective, compact and easy-to-use method of detection for analytes. In the scope of this dissertation, we investigated the feasibility of functional zein nanocomposite films and formation of a zein nanocomposite sensor assembly for rapid and highly selective electrochemical measurements of food toxins and allergens. Fabrication of a zein based electrochemical amperometric sensor assembly was studied, first through the comparison of various zein film characteristics changes with the application of Laponite®, graphene oxide and carbon nanotube nanoparticles, followed by a proof-of-concept study by detecting the gluten allergen protein gliadin.

To mechanistically study the functional zein nanocomposite films, Laponite®, a silica nanoparticle, was added in the presence of 70% ethanol solvent and oleic acid plasticizer. The films were studied using various characterization techniques like transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), water contact angle measurements etc. Through Si-N bond formation between Laponite® and zein, fabricated zein nanocomposite films showed increase in surface hydrophobicity, water vapor barrier properties, tensile strength and Young’s modulus. Graphene oxide (GO), a carbon nanoparticle, was also incorporated into zein through the solvent casting process. Uniform dispersion of GO nanoparticles within zein matrix were confirmed up to 1% GO loading, and covalent and hydrogen bonding mechanisms were proposed. Similar to zein-Laponite® (Z-LAP) nanocomposites, zein-GO (Z-GO) showed increase in hydrophobic tendencies, rougher surface and a 300% improvement in Young’s modulus and 180% improvement in tensile strength at only 3% GO loading. Both nanoparticles increased tensile strength, thermal stability and water vapor barrier property of the films, indicating a potential for food packaging as an alternative application for the nanocomposite films.

Finally, the research focused on the fabrication of an electrochemical amperometric sensor, capable of detecting the protein gliadin, which is responsible for the allergic reaction with people having celiac disease. Novel biodegradable coatings made from zein nanocomposites: zein-graphene oxide, zein-Laponite® and zein-multiwalled carbon nanotubes (Z-CNT) using drop casting technique were tested for fabricating the electrochemical sensors using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV) techniques. As Z-CNT produced the strongest signals compared to other nanomaterials, the active tip of the electrochemical sensor was functionalized through a sequence of layer by layer deposition of Z-CNT nanocomposite, antibody and target analyte. Here, Z-CNT acts as a natural linker molecule with large number of functional groups, that causes immobilization of capture antibody and target, to ensure high sensor performance. Both CV curves and SWV curves indicated successful sequential immobilization of gliadin antibody onto the Z-CNT coated electrode. The Z-CNT biosensor was successfully able to give CV signals for gliadin toxins for as low as 0.5 ppm and was highly specific for gliadin in the presence of other interfering molecules, and remained stable over a 30-day period. The low-cost, thin, conductive zein films offered a promising alternative for protein immobilization platforms used in sensors and can be extended to other matrices in biosensors as well as other functional film applications

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31

Ghosh, Somnath. "Investigation On Ag And ZnO Based Nanohybrids As Bactericides For The Purification Of Water And Elucidation Of Possible Mechanisms For Their Bio-activity." Thesis, 2012. https://etd.iisc.ac.in/handle/2005/2492.

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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.

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32

Ghosh, Somnath. "Investigation On Ag And ZnO Based Nanohybrids As Bactericides For The Purification Of Water And Elucidation Of Possible Mechanisms For Their Bio-activity." Thesis, 2012. http://hdl.handle.net/2005/2492.

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Abstract:

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.

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