Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2017-09-27T11:09:10Z No. of bitstreams: 2 Dissertação - Ionara Pereira da Silva Sousa - 2017.pdf: 5120392 bytes, checksum: 786f15ae0e6cf83fa9560a114e84f6a2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-09-27T11:09:36Z (GMT) No. of bitstreams: 2 Dissertação - Ionara Pereira da Silva Sousa - 2017.pdf: 5120392 bytes, checksum: 786f15ae0e6cf83fa9560a114e84f6a2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-09-27T11:09:36Z (GMT). No. of bitstreams: 2 Dissertação - Ionara Pereira da Silva Sousa - 2017.pdf: 5120392 bytes, checksum: 786f15ae0e6cf83fa9560a114e84f6a2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-09-15 / The basic science on cements and concretes has incorporated research related to the understanding of the effects of the addition of nanosilica, and more recently functionalized nanosilicas, on the properties of cement pastes, mortars and concretes. In this context, the aim of this work was to prepare amino-functionalized nanosilicas from a commercial nanosilica (NS), provided as an aqueous colloidal suspension, by employing 3-aminopropiltrietoxissilano (APTS) as reactant, and to evaluate the characteristics of the samples. The functionalization reactions were performed in a biphasic system composed of dichloromethane and water, and employing different APTS/NS molar ratios. The materials were obtained as aqueous suspensions and their characteristics were evaluated at pH 4, 7 e 10. The functionalization of NS was evidenced by the presence of infrared bands associated to the aminopropyl group. Bands associated to silanol (-SiOH) and alcoxide (Si-OCH2CH3) groups were observed indicating that the hydrolysis and condensation reactions were not complete. The 29Si NMR signals of Si-C bonds confirmed the functionalization. The thermogravimetric curves indicated an increase of the amount of aminopropyl groups incorporated on NS as the APTS/NS ratio increased. Transmission electron microscopy images showed an increase in the mean particle sizes after functionalization. The aqueous suspended nanoparticles showed a positive zeta potential at pH 4 (+23 to +27 mV) and at pH 7 (+14 to +29 mV), indicating the presence of protonated amine groups. The zeta potential at pH 10 was weakly negative (-0.10 to -7,6 mV) for the samples prepared from the lower APTS/NS molar ratios (7.1 and 14.2 x 10-2), and still positive (+11 and +15 mV) for those prepared from the higher molar ratios (28.5 and 42.7 x 10-2), suggesting the existence of a higher amount of superficial amino groups within the latter. The mean hydrodynamic radius of the functionalized particles were greater (22 a 281 nm) than that of the NS (12 nm) at all pH values, with superior values for suspended particles at pH 10, particularly for samples prepared from the lower APTS/NS ratios. The amount of aggregates of bigger size (~100 to 2000 nm) was greater for samples prepared from the lower APTS/NS ratios. These variable characteristics are interesting for comparative studies involving the effects of the addition of these suspensions in cement pastes over the microstructure and properties of the resulting materials. / A ciência básica na área de cimentos e concretos tem incorporado pesquisas relacionadas ao entendimento dos efeitos da adição de nanossílica e, mais recentemente, de nanossílica funcionalizada nas propriedades de pastas de cimento, argamassas e concretos. Neste contexto, o objetivo deste trabalho foi preparar nanossílicas funcionalizadas com grupos amina a partir de uma nanossílica comercial (NS), fornecida como uma suspensão coloidal aquosa, empregando-se o reagente 3-aminopropiltrietoxissilano (APTS) e avaliar as características das amostras obtidas. As reações de funcionalização foram realizadas em um sistema reacional bifásico constituído de diclorometano e água, empregando-se diferentes razões molares APTS/NS. Os materiais foram obtidos como suspensões aquosas, cujas características foram avaliadas em pH 4, 7 e 10. A funcionalização da NS foi evidenciada pela presença das bandas relativas ao grupo aminopropil nos espectros de infravermelho, onde também foram observadas bandas dos grupos silanol (-SiOH) e alcóxido (Si-OCH2CH3), indicando que as reações de hidrólise e condensação não foram completas. Os sinais nos espectros de RMN de 29Si característicos de ligações Si-C confirmaram a funcionalização. As curvas termogravimétricas indicaram que houve aumento no teor de grupos aminopropil incorporados à NS com o aumento da razão APTS/NS empregada. As imagens de microscopia eletrônica de transmissão mostraram um aumento do tamanho médio das partículas após a funcionalização. As nanopartículas funcionalizadas em suspensão aquosa apresentaram potencial zeta positivo em pH 4 (+23 a +27 mV) e em pH 7 (+14 a +29 mV), indicando a presença de grupos amina protonados. Já em pH 10, o potencial zeta foi fracamente negativo (-0,10 a -7,6 mV) para amostras preparadas com menor razão APTS/NS (7,1 e 14,2 x 10-2), e positivos (+11 e +15 mV) para aquelas preparadas com razão molar maior (28,5 e 42,7 x 10-2), sugerindo um maior teor de grupos amina superficiais nestas últimas. Os raios hidrodinâmicos médios das partículas funcionalizadas foram maiores (22 a 281 nm) do que o da NS (12 nm) para todos os valores de pH, com valores maiores para partículas suspensas em pH 10. O teor de agregados de maior tamanho (~100 a 2000 nm) foi maior para as amostras preparadas com menor razão APTS/NS. Essas características variadas são interessantes para estudos comparativos dos efeitos de adição dessas suspensões em pastas de cimento, sobre a microestrutura e propriedades dos materiais resultantes.

No description available.

Surface chemical gradients are materials that exhibit continuous, gradually varying chemical or physical properties along and across the length of a substrate. As a result, each point on the gradient surface can represent an individual sample. They are broadly classified as chemical and physical gradients depending upon the properties that the gradient exhibits. A physical gradient involves a continuous variation of physical properties such as surface roughness and film porosity on the micrometer scale. Chemical gradients involve a gradual variation of chemical properties such as polarity, acidity and basicity, etc. Such gradients have found various applications in cell adhesion, nanoparticle absorption, etc. Because of the multitude of potential applications of acid-base gradient materials in separation science and biological applications, the main work of this dissertation work is focused on the preparation and fundamental, molecular level investigation of acid-base gradients on siloxane surfaces. In this work, we focused on the preparation and characterization of surface charge gradients. Charged gradients are gradients that contain charged functional groups that are spatially distributed along the length of the substrate. They can interact with each other or with other species in solution by electrostatic interactions. They can also play a key role in governing the interaction of macromolecules and bacteria on surfaces, the wetting of surfaces, the layer-by-layer (LBL) assembly of thin films, reactions in catalysis, and the separation of charged species in chromatography. Therefore, understanding localized interactions between surface functional groups and charged species in solution are particularly relevant to the development of surfaces resistant to biofouling, antimicrobial surfaces, catalytic surfaces, multi-layered composite thin films, and imprinted surfaces for chemical sensing and separations. Thus, it is of great of interest to develop methodologies to create and study heterogeneous and homogeneous charged surfaces with well-defined properties. There have been several different methods developed for the preparation of charged gradients. First a chemical gradient is prepared and then the chemical gradient is converted to charged gradient by a chemical approach. Silane-based methods for the preparation of chemical gradients are among those that are widely used because of the straightforwardness of the chemistry involved and also the availability of silanes with various chemical functionalities. A few of these silane based approaches such as the vapor-diffusion method and liquid diffusion method have been used for various applications so far. Most of these methods are only able to prepare surface chemical gradients for a specific application mainly because of their limitations in terms of gradient-length scale and chemistry involved. In this work, we used a procedure already developed in our lab to prepare chemical gradients from different functionalized alkoxysilanes; we call this procedure the ‘controlled-rate infusion method (CRI)’. This method can be adapted to different substrates and can form gradients at various length-scales, such as few hundred microns to tens of centimeters. The CRI method involves the infusion of an organoalkoxysilane solution into a container with a substrate mounted vertically so that time-dependent exposure along the substrate forms a gradient in chemical functionality from bottom to the top. The most important attribute of this method is that the local steepness of the gradient can be systematically controlled by simply changing the rate of infusion. The steepness of the gradient can also be changed at predefined positions along its length by programming the rate of infusion. CRI can also be used to prepare gradients containing multiple functionalities, termed multicomponent chemical gradients. The different chemical functionalities can be oriented in different directions to produce gradients where functionalities can be oriented along the same or opposed directions producing aligned and opposed multicomponent chemical gradients, respectively. In this work, the multicomponent gradients were converted to charge gradients via chemical reaction with 30% H2O2. Using controlled rate infusion and this technique, aligned or opposed multicomponent charge gradients containing NH3+, SO3- and SiO- groups were prepared. By infusing 3-aminopropyltriethoxysilane (APTEOS) and 3-mercaptopropyltriethoxysilane (MPTMOS) in the same or opposed direction, gradients containing charged species in different locations relative to each other along the length of the substrate were made. The gradient properties in each case were different and correlated to the way they were prepared i.e., where the gradients were oriented in an aligned or opposed fashion. Surface wettability and local surface charge, etc were found to be entirely different depending on the type of charge gradients (aligned and opposed). In another example, SiO- and NH3+ opposed gradients were prepared by infusing APTEOS on different base layers prepared from tetramethoxysilane (TMOS), phenyltrimethoxysilane (PTMOS), dimethyldimethoxysilane (DMDMOS) or octyltrimethoxysilane (OTMOS) followed by protonation of the surface amines. The gradient profiles and surface wettability were found to be independent of each other and dependent of the type of the base layer. In summary, this dissertation work focuses mainly on the preparation of multicomponent charge gradients and their molecular level characterization by a multitude of different analytical methods including XPS spectroscopy, tapping mode atomic force microscopy (TM-AFM), zeta potential measurement, and SCA and DCA measurements. CRI has incredible flexibility and adaptability, which was confirmed by extending it to different siloxane base films and creating gradients with different functionalities. Multicomponent charge gradients containing acid and base functionalities can be prepared and optimized for and acid base catalysis reactions such Michael addition as well as aldol, Henry, and Knoevenagel condensations.

L’objectif de mon doctorat, réalisé dans le cadre d’une collaboration entre le laboratoire des protéines et nanotechnologies en sciences séparatives (institut Galien Paris-Sud) et le groupe Micro et Nano Système (institut d’électronique fondamentale) était d’étudier l’influence des monocouches autoassemblées, sur l’activité biologique du bio-récepteur dans une perspective de développement de biocapteur. Dans ce projet, nous avons choisi les organo-silanes qui peuvent se lier de manière covalente sur le silicium. Deux silanes (7-octenyl trichlorosilanes et le (3-aminopropyl)triethoxysilane) ont été étudiés, leur impact en terme de nature et de stabilité sur la fonctionnalité du bio-récepteur, des immunoglobulines G de souris, ont été évalué. Dans un premier temps, nous nous sommes intéressés à la fonctionnalité des anticorps greffés sur une mono couche auto-assemblée composée de 7-octenyltrichlorosilane (OTS) présentant à sa surface un groupement carboxylique. Une caractérisation spectroscopique par XPS et infra-rouge à transformé de Fourrier (FTIR) a tout d’abord été effectuée afin de vérifier la présence de ces groupements carboxyliques. L’homogénéité de la surface a été évaluée par AFM. Nous avons ensuite immobilisé ces anticorps, sur ces supports, de manière covalente et une étude topographique par AFM a été menée pour mesurer la répartition de ces anticorps. L’orientation des anticorps greffés a été évaluée à l’aide d’immuno-essais. Ensuite, nous avons comparé l’APTES, permettant l’obtention de plaques de silicium fonctionnalisé avec des groupements aminés à leur surface, avec l’OTS. Nous avons notamment comparé la capacité de capture des anticorps immobilisés sur ces deux types de silanes. Dans la dernière partie, l’impact du vieillissement d’un support immunologique préparé chimiquement en utilisant l’APTES a été évaluée sur le plan physico-chimique et biologique. / The aim of my PhD thesis, conducted as part of a collaboration between the laboratory of protein separation sciences and nanotechnology (Paris-Sud Galen Institute) and the Micro and Nano System (basic electronics institute) group was to study the influence of self-assembled monolayers on the biological activity of bioreceptor toward biosensor development. In this project, we choose the organosilanes that can bind covalently to the silicon. Two silanes (7-octenyl trichlorosilane(OTS) and 3- aminopropyltriethoxysilane (APTES)) were studied., Their impact on the stability and the functionality of bio- receptor , model mouse immunoglobulin G (IgG), were evaluated. Spectroscopic characterization by XPS and infra- red Fourier transformed (FTIR) was first carried out to assess that the silanized surface exhibit carboxylic groups. The homogeneity of the surfaces was measured by AFM. Then, IgG were immobilized on these supports, covalently and a topographic AFM study was conducted to measure the distribution of these antibodies. The orientation of the grafted antibody was investigated by immune-enzymatic assays. We have also evaluated the binding capacity of the IgG immobilized on both surfaces. Then, the impact of aging on APTES surface was evaluated by spectroscopics and biological methods.

Atualmente com o advento da nanociência e nanotecnologia, as nanopartículas magnéticas têm encontrado inúmeras aplicações nos campos da biomedicina, diagnóstico, biologia molecular, bioquímica, catálise, etc. As nanopartículas magnéticas funcionalizadas são constituídas de um núcleo magnético, envolvido por uma camada polimérica com sítios ativos, que podem ancorar metais ou compostos orgânicos seletivos. Estas nanopartículas são consideradas materiais híbridos orgânico-inorgânicos de grande interesse em aplicações comerciais devido à particularidade das propriedades obtidas. Entre as aplicações importantes podemos citar: tratamento por magnetohipertermia, carregadores de fármacos para áreas específicas do corpo, seleção de moléculas específicas, biossensores, melhoria da qualidade de imagens por RMN, etc. O trabalho foi desenvolvido em duas partes: 1) a síntese do núcleo constituído de nanopartículas superparamagnéticas de ferrita de cobalto e, 2) o recobrimento do núcleo por um polímero bifuncional o 3-aminopropiltrietoxissilano. Os parâmetros estudados na primeira parte da pesquisa foram: pH, concentração molar da base, tipo de base, ordem de adição dos reagentes, modo de adição dos reagentes, velocidade de agitação, concentração inicial dos metais, fração molar de cobalto e tratamento térmico. Na segunda parte estudou-se: o pH, a temperatura, o catalisador, a concentração do catalisador, o tempo de reação, a relação H2O/silano, o tipo de meio, o agente umectante e a eficiência do recobrimento em relação ao pH. Os produtos obtidos foram caracterizados pelas técnicas de difratometria de raios-X (DRX), microscopia eletrônica de transmissão (MET), microscopia eletrônica de varredura (MEV), espectroscopia de energia dispersiva (EDS), espectroscopia de emissão atômica (ICP-AES), espectroscopia por infravermelho (FTIR), análises termogravimétricas (TGA/DTGA), calorimetria exploratória diferencial (DSC) e curvas de magnetização (MAV) / Nowadays with the appear of nanoscience and nanotechnology, magnetic nanoparticles have been finding a variety of applications in the fields of biomedicine, diagnosis, molecular biology, biochemistry, catalysis, etc. The magnetic functionalized nanoparticles are constituted of a magnetic nucleus, involved by a polymeric layer with active sites, which ones could anchor metals or selective organic compounds. These nanoparticles are considered organic-inorganic hybrid materials and have great interest as materials for commercial applications due to the specific properties. Among the important applications it can be mentioned: magnetohyperthermia treatment, drugs delivery in specific local of the body, molecular recognition, biossensors, enhancement of nuclear magnetic ressonance images quality, etc. This work was developed in two parts: 1) the synthesis of the nucleus composed by superparamagnetic nanoparticles of cobalt ferrite and, 2) the recovering of nucleus by a polymeric bifunctional 3-aminepropyltriethoxysilane. The parameters studied in the first part of the research were: pH, hydroxide molar concentration, hydroxide type, reagent order of addition, reagent way of addition, speed of shake, metals initial concentrations, molar fraction of cobalt and thermal treatment. In the second part it was studied: pH, temperature, catalyst type, catalyst concentration, time of reaction, relation ratios of H2O/silane, type of medium and the efficiency of the recovering regarding to pH. The products obtained were characterized using the following techniques X-ray powder diffraction (DRX), transmission electronic microscopy (MET), scanning electronic microscopy (MEV), spectroscopy of scatterbrained energy spectroscopy (DES), atomic emission spectroscopy (ICP-AES), themogravimetric analysis (TGA/DTGA), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and magnetization curves (VSM)

[pt] O objetivo deste trabalho foi estudar a funcionalização química de nanotubos de titanato (TTNTs) com 3-aminopropiltrietoxisilano, para uso como reforço de nanocompósitos de matriz náilon-11, com o intuito de melhorar a dispersão e compatibilidade destas nanocargas com a matriz polimérica. Foram sintetizadas duas amostras: TTNTs/H e TTNTs/L, com alto e baixo teor sódio respectivamente, funcionalizadas em uma solução etanol/água 95/5 v/v e água para avaliar o efeito do meio de reação na quantidade de silano enxertada na superfície dos TTNTs, expressa como densidade de grupos aminopropil por nm2 (NR). Os TTNTs funcionalizados foram caracterizados por espectroscopia de infravermelho, análise elementar de CHN, medição da área superficial específica, termogravimetria e microscopias eletrônicas de varredura e de transmissão. Foram fabricados nanocompósitos de matriz náilon-11 por microextrusão-microinjeção, reforçados com TTNTs de partida e funcionalizados em concentrações de 0.5, 1.0 e 2.0 porcento wt. Finalmente, foram avaliadas as propriedades mecânicas, térmicas e microestruturais dos nanocompósitos. Os resultados demonstraram a formação da ligação covalente Ti-O-Si e revelaram um maior valor de NR quando o meio de reação foi etanol/água para ambos os TTNTs. Os nanocompósitos reforçados com TTNTs/H funcionalizados em água e TTNTs/L silanizados em mistura etanol/água, em uma proporção de 2 porcento wt, apresentaram um incremento no módulo de elasticidade de 11 e 13 porcento respectivamente, com um decréscimo das propriedades no escoamento e um aumento na temperatura de degradação, quando comparados com o náilon-11 puro. O nanocompósito que apresentou a melhor dispersão foi o fabricado com 0.5 porcento wt. TTNTs/L silanizados em etanol/agua. / [en] The aim of this work was to study the chemical functionalization of titanate nanotubes (TTNTs) with 3-aminopropyltriethoxysilane for application as a reinforcement of nylon-11 matrix nanocomposites in order to increase the dispersion and compatibility between nanotubes and the polymer matrix. Two samples with high and low sodium content (TTNTs/H and TTNTs/L, respectively) were functionalized in a solution of ethanol/water 95/5 v/v and water to assess the effect of the reaction medium on the amount of silane grafted on the TTNTs surface, expressed as the density of aminopropyl groups per nm2 (NR). The functionalized nanotubes were characterized by infrared spectroscopy, CHN elemental analysis, measurement of the specific surface area, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. Nylon-11 matrix nanocomposites were manufactured by microextrusionmicroinjection and reinforced with 0.5, 1.0 and 2.0 wt. percent of pristine and functionalized nanotubes. Finally, mechanical and thermal properties as well as the microstructure of the nanocomposites were evaluated. The results confirmed the Ti-O-Si covalent bond and showed a higher NR value when the silanization was performed in ethanol/water for both TTNTs. The nanocomposites reinforced with 2 wt. percent of TTNTs/H (silanized in water) and with TTNTs/L (silanized in ethanol/water) presented an enhancement on the Young s modulus of 11 and 13 percent, respectively when compared with the neat nylon-11. The yield properties of these nanocomposites decreased, but the degradation temperature was improved with the incorporation of the functionalized nanotubes. The nanocomposite prepared with 0.5 wt. percent TTNTs/L silanized in ethanol/water showed the best dispersion.

The aim of this study was to investigate rubber toughening of resol type phenol-formaldehyde resin. For this purpose, phenolic resin was first modified by only acrylonitrile butadiene rubber, and then by using nitrile rubber together with 3-aminopropyltriethoxysilane. Test specimens were prepared by mixing and casting of liquid phenolic resin in three groups. In the first one, neat phenolic resin specimens were produced. In the second group, phenolic resin was modified with 0.5, 1, 2, and 3 wt.% nitrile rubber, while in the last group modification was carried out by using 0.5 wt.% nitrile rubber together with 1, 2, and 4wt.% amino silane (with respect to nitrile rubber). All specimens were heat cured in the oven. In order to observe behaviors of the specimens, Three-Point Bending, Charpy Impact, Plane-Strain Fracture Toughness, and Dynamic Mechanical Analysis tests were conducted according to the related ISO standards for all specimens groups. Scanning Electron Microscopy was also used for the fractographic analysis of some samples. It can be concluded that, although there were problems in mixing and casting of liquid resol type phenolic resin, its toughness could be improved by using nitrile rubber and amino silane. Modification by using nitrile rubber and amino silane together was much more effective than by using only nitrile rubber. In this synergistic case for instance, Charpy impact strength and fracture toughness values of the neat phenolic specimens were increased 63% and 50%, respectively. SEM studies indicated that the main rubber toughening mechanism was shear yielding observed as deformation lines especially initiated at the domains of nitrile rubber and amino silane.

Made available in DSpace on 2014-06-11T19:25:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-01-26Bitstream added on 2014-06-13T19:12:22Z : No. of bitstreams: 1 sa_ac_me_ilha.pdf: 1061286 bytes, checksum: b370fdf160f4689709efe584af803c2a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste trabalho esta resumido através de três etapas. 1 - A primeira etapa consistiu em funcionalizar e caracterizar a sílica gel com grupos 3- aminopropiltrietoxisilano. Nesta etapa o material obtido (Si) foi caracterizado por técnicas de Ressonância Magnética Nuclear no estado sólido (24Si e 13C) e espectroscopia vibracional (FTIR). 2- Numa segunda etapa promoveu-se a adsorção de íons de cobre (II) e de cobalto (II) na superfície da sílica (Si). Os materiais obtidos (SiCu e SiCo) foram caracterizados por espectroscopia vibracional e voltametria cíclica. 3- Na terceira etapa reagiu-se os materiais preparados (SiCu e SiCo) com nitroprussiato de sódio para formar os complexos binucleares (SiCuNP e SiCoNP). Estes materiais também foram caracterizados por espectroscopia vibracional e voltametria cíclica. Estes materiais foram utilizados na construção do eletrodo de pasta de grafite e testados na oxidação eletrocatalítica de substâncias biologicamente importantes tais como a hidrazina e N-acetilcisteína sendo empregado para isto a técnica de voltametria cíclica. Observou-se que o eletrodo de SiCuNP apresentam dois pares redox nos potenciais (Em)1 = 0,34 V e (Em)2 = 0,76 V vs Ag/AgCl, O primeiro foi atribuído ao processo de oxidação do par Cu(I)/Cu(II) e o segundo ao processo de oxidação Fe(II)(CN)5NO / Fe(III)(CN)5NO do complexo binuclear. O sistema SiCoNP foram observados dois pares redox distintos com os seguintes potenciais médios (Em); (Em)1 = 0,29 V e (Em)2 = 0,56 V vs Ag/AgCl, o primeiro foi atribuído ao processo redox do par Co(II)/Co(III) e o segundo ao processo redox Fe(II)(CN)5NO / Fe(III)(CN)5NO do complexo binuclear formado. O sistema SiCuNP foi sensível a concentração de hidrazina apresentando um limite de detecção e sensibilidade amperométrica de 3,07×10-4 mol L-1 e 5,84×10-6 A / mol L-1... / The objective of this work is summarized in three stages. 1 - The first stage functionalizes and characterizes the silica gel with 3-aminopropyltriethoxysilane groups. At this stage the material obtained (Si) was characterized by solid state Nuclear Magnetic Resonance techniques (24Si and 13C) and vibrational spectroscopy (FTIR). 2 - The second stage promotes the adsorption of copper (II) and cobalt (II) ions on the surface of the silica (Si). The materials obtained (SiCu and SiCo) were characterized by vibrational spectroscopy and cyclic voltammetry. 3 - The third stage prepares the reaction of the materials (SiCu and SiCo) with sodium nitroprusside to form the binuclear complex (SiCuNP and SiCoNP). These materials were characterized by vibrational spectroscopy and cyclic voltammetry. These materials were used to construct the electrode carbon paste and were tested for electrocatalytic oxidation of biologically important substances such as hydrazine and N-acetylcysteine using the cyclic voltammetry technique. It was observed that the electrode SiCuNP has two redox pairs in the potential (Em)1 = 0.34 V and (Em)2 = 0.76 V vs. Ag/AgCl, the first was attributed to the oxidation process of the pair Cu(I)/Cu(II) and the second to the oxidation process Fe(II)(CN)5NO / Fe(III)(CN)5NO of the binuclear complex. For the SiCoNP system, two distinct redox couples were observed with the following mean potentials (Em); (Em)1 = 0.29 V and (Em)2 = 0.56 V vs Ag/AgCl, the first one was assigned to the redox process of the Co(II)/Co(III) pair and the second one to the redox process Fe(II)(CN)5NO / Fe(III)(CN)5NO of the binuclear complex formed. The SiCuNP system was sensitive to the hydrazine concentration, exhibiting a detection limit and amperometric sensitivity of 3.07×10-4 mol L-1 and 5.84×10-6 A / mol L-1 respectively and was also... (Summary complete electronic access click below)

Atualmente com o advento da nanociência e nanotecnologia, as nanopartículas magnéticas têm encontrado inúmeras aplicações nos campos da biomedicina, diagnóstico, biologia molecular, bioquímica, catálise, etc. As nanopartículas magnéticas funcionalizadas são constituídas de um núcleo magnético, envolvido por uma camada polimérica com sítios ativos, que podem ancorar metais ou compostos orgânicos seletivos. Estas nanopartículas são consideradas materiais híbridos orgânico-inorgânicos de grande interesse em aplicações comerciais devido à particularidade das propriedades obtidas. Entre as aplicações importantes podemos citar: tratamento por magnetohipertermia, carregadores de fármacos para áreas específicas do corpo, seleção de moléculas específicas, biossensores, melhoria da qualidade de imagens por RMN, etc. O trabalho foi desenvolvido em duas partes: 1) a síntese do núcleo constituído de nanopartículas superparamagnéticas de ferrita de cobalto e, 2) o recobrimento do núcleo por um polímero bifuncional o 3-aminopropiltrietoxissilano. Os parâmetros estudados na primeira parte da pesquisa foram: pH, concentração molar da base, tipo de base, ordem de adição dos reagentes, modo de adição dos reagentes, velocidade de agitação, concentração inicial dos metais, fração molar de cobalto e tratamento térmico. Na segunda parte estudou-se: o pH, a temperatura, o catalisador, a concentração do catalisador, o tempo de reação, a relação H2O/silano, o tipo de meio, o agente umectante e a eficiência do recobrimento em relação ao pH. Os produtos obtidos foram caracterizados pelas técnicas de difratometria de raios-X (DRX), microscopia eletrônica de transmissão (MET), microscopia eletrônica de varredura (MEV), espectroscopia de energia dispersiva (EDS), espectroscopia de emissão atômica (ICP-AES), espectroscopia por infravermelho (FTIR), análises termogravimétricas (TGA/DTGA), calorimetria exploratória diferencial (DSC) e curvas de magnetização (MAV) / Nowadays with the appear of nanoscience and nanotechnology, magnetic nanoparticles have been finding a variety of applications in the fields of biomedicine, diagnosis, molecular biology, biochemistry, catalysis, etc. The magnetic functionalized nanoparticles are constituted of a magnetic nucleus, involved by a polymeric layer with active sites, which ones could anchor metals or selective organic compounds. These nanoparticles are considered organic-inorganic hybrid materials and have great interest as materials for commercial applications due to the specific properties. Among the important applications it can be mentioned: magnetohyperthermia treatment, drugs delivery in specific local of the body, molecular recognition, biossensors, enhancement of nuclear magnetic ressonance images quality, etc. This work was developed in two parts: 1) the synthesis of the nucleus composed by superparamagnetic nanoparticles of cobalt ferrite and, 2) the recovering of nucleus by a polymeric bifunctional 3-aminepropyltriethoxysilane. The parameters studied in the first part of the research were: pH, hydroxide molar concentration, hydroxide type, reagent order of addition, reagent way of addition, speed of shake, metals initial concentrations, molar fraction of cobalt and thermal treatment. In the second part it was studied: pH, temperature, catalyst type, catalyst concentration, time of reaction, relation ratios of H2O/silane, type of medium and the efficiency of the recovering regarding to pH. The products obtained were characterized using the following techniques X-ray powder diffraction (DRX), transmission electronic microscopy (MET), scanning electronic microscopy (MEV), spectroscopy of scatterbrained energy spectroscopy (DES), atomic emission spectroscopy (ICP-AES), themogravimetric analysis (TGA/DTGA), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and magnetization curves (VSM)

Les travaux présentés dans ce mémoire concernent la caractérisation par infrarouge à transformée de Fourier (FTIR) et par spectroscopie d’émission optique (SEO) des réactions chimiques entre post-décharges et précurseurs organosiliciés, avec comme exemple le cas du 3-aminopropyltriéthoxysilane (APTES). Le but est d’obtenir la rétention la plus élevée possible de fonctions amine -NH2 dans les revêtements ou dans les nanoparticules synthétisées. Tout d’abord, un état de l’art des post-décharges Ar-N2 et Ar-O2 et leurs applications est présenté ainsi que la cinétique d’interaction de l’APTES dans ces post-décharges, mettant en évidence le rôle des mélanges plasmagènes sur la décomposition du précurseur et sur la nature des films déposés. Ensuite l’étude de la décomposition de l’APTES dans une post-décharge Ar-N2 est réalisée. Les analyses par SEO et par FTIR in situ montrent le rôle des atomes d’azote N dans la formation des différents sous-produits, à savoir HCN, CO et C=O. Les nanoparticules synthétisées contiennent peu d’amine primaire, et présentent une concentration non négligeable d’azote sous forme d’amide secondaire. Dans le cas de l’étude de la décomposition de l’APTES dans la post-décharge Ar-O2 en mode pulsé, une tendance se dessine : les nanoparticules synthétisées en phase gazeuse lorsque les rapports cycliques augmentent ont une composition qui s’appauvrit en azote et en carbone mais s’enrichit en oxygène. Les groupements NH2 initiaux sont fortement convertis en groupement amide. Les nanoparticules synthétisées avec des rapports cycliques élevés ont des compositions différentes de celles des films minces déposés sur les parois, plus proches de la silice et ce en raison de la gravure par l’oxygène atomique qui les affecte davantage. Le comportement spécifique des atomes d’oxygène et d’azote en post-décharge rend difficile la rétention des amines dans les polymères plasmas. Enfin nous avons terminé par une étude de l’hydrodynamique dans le cas de l’interaction entre l’acétylène et une post-décharge Ar-O2 et établi l’importance de l’écoulement sur toute approche visant à faire des mesures FTIR résolues temporellement / The present work deals with the characterization by Fourier transform infrared spectroscopy (FTIR) and by optical emission spectroscopy of chemical reactions between a post-discharge and an organosilicon precursor: the 3-aminopropyltriethoxysilane (APTES). The aim is to keep the highest retention of amine functions -NH2 in coatings or in the synthesized nanoparticles. First, a state of the art of Ar-N2 and Ar-O2 post-discharges and their applications is presented as well as the kinetics of the interaction of APTES in these post-discharges, highlighting the role plasma gases on the decomposition of the precursor and the nature of the deposited films. Then, the study of the decomposition of APTES in an Ar-N2 post-discharge is carried out. Analysis by optical emission spectroscopy (OES) and in situ FTIR show the role of the nitrogen atoms N in the formation of various main by-products, namely HCN, CO and C=O. The synthesized nanoparticles contain few primary amines, and have a significant concentration of nitrogen in the form of secondary amide. In the case of interaction APTES with pulsed Ar-O2 afterglow, there is one main trend: the nanoparticles synthesized in the gas phase when the duty cycle increases have a composition that decreases in nitrogen and carbon but increases in oxygen. The -NH2 groups are efficiently converted into amide groups. The nanoparticles synthesized with high duty cycle exhibit compositions that are different from those of thin films deposited on the walls, the latter being close to silica because of the etching by atomic oxygen, which affects them more. The specific behavior of oxygen and nitrogen atoms in post-discharge makes difficult the retention of a high level of amines in plasma polymers. Finally, we finished with a study of the hydrodynamics in the case of the interaction of acetylene with an Ar-O2 post-discharge and proved the key role of the flow for any approach aiming at getting time-resolved FTIR measurements