This thesis describes the synthesis, characterisation and catalytic testing of multifunctional immobilised metal nanoparticle in metal-organic framework (MOF) materials. Combining the activity of metal nanoparticles with the porosity and Lewis acidity of metal-organic frameworks provides a single catalytic material which can perform multi-step reactions. Strategies to immobilise the metal nanoparticles within the metal-organic frameworks have been investigated. Immobilisation has been achieved by applying three different methodologies. First, deposition of metal nanoparticle precursors within mesoporous MOFs is discussed. Chapter 3 shows the effectivity of the double solvents deposition technique to achieve dispersed and small nanoparticles of around 2.7 nm. The best system combined Pd nanoparticles with MIL-101(Cr). This system was further investigated in tandem reductive amination catalysis, discussed in Chapter 4, to investigate the activity and selectivity provided by these multifunctional catalysts. Another immobilisation technique was performed by coating Pd decorated SiO2 spheres with a MOF layer. Using this technique, MOF was grown cyclically in solution, providing tuneable shell thicknesses of MOF on the metal nanoparticle decorated oxide spheres. While the homogeneity of the MOF shell needs more optimisation, it was determined that the surface charge on the spheres played an important role in the growth of MOF in the desired location. Finally, the third immobilisation technique is the core-shell growth of MOF on colloidal metal nanoparticles. Polymer-capped metal nanoparticles with well-defined shapes were synthesised and characterised. From here, the optimisation of conditions for core-shell growth of UiO-66 and MIL-100(Sc) were investigated. Conditions which provided the desired core-shell morphology were found for both MOF types. These materials were then subsequently used in tandem reductive amination catalysis and a more straightforward styrene hydrogenation. It was shown that the metal nanoparticles remain active catalysts within either MOF shell and the MOF shell stabilises the metal nanoparticle and acts as a Lewis acid catalyst.

abstract: With a recent shift to a more environmentally conscious society, low-carbon and non-carbon producing energy production methods are being investigated and applied all over the world. Of these methods, fuel cells show great potential for clean energy production. A fuel cell is an electrochemical energy conversion device which directly converts chemical energy into electrical energy. Proton exchange membrane fuel cells (PEMFCs) are a highly researched energy source for automotive and stationary power applications. In order to produce the power required to meet Department of Energy requirements, platinum (Pt) must be used as a catalyst material in PEMFCs. Platinum, however, is very expensive and extensive research is being conducted to develop ways to reduce the amount of platinum used in PEMFCs. In the current study, three catalyst synthesis techniques were investigated and evaluated on their effectiveness to produce platinum-on copper (Pt@Cu) core-shell nanocatalyst on multi-walled carbon nanotube (MWCNT) support material. These three methods were direct deposition method, two-phase surfactant method, and single-phase surfactant method, in which direct deposition did not use a surfactant for particle size control and the surfactant methods did. The catalyst materials synthesized were evaluated by visual inspection and fuel cell performance. Samples which produced high fuel cell power output were evaluated using transmission electron microscopy (TEM) imaging. After evaluation, it was concluded that the direct deposition technique was effective in synthesizing Pt@Cu core-shell nanocatalyst on MWCNTs support when a rinsing process was used before adding platinum. The peak power density achieved by the rinsed core-shell catalyst was 618 mW.cm-2 , 13 percent greater than that of commercial platinum-carbon (Pt/C) catalyst. Transmission electron microscopy imaging revealed the core-shell catalyst contained Pt shells and platinum-copper alloy cores. Rinsing with deionized (DI) water was shown to be a crucial step in core-shell catalyst deposition as it reduced the number of platinum colloids on the carbon nanotube surface. After evaluation, it was concluded that the two-phase surfactant and single-phase surfactant synthesis methods were not effective at producing core-shell nanocatalyst with the parameters investigated. / Dissertation/Thesis / M.S.Tech Technology 2012

Híbridos poliuretano-acrílicos foram sintetizados via polimerização em emulsão, utilizando uma dispersão de poliuretano base poliol poliéster como semente para a polimerização dos monômeros acrílicos, no caso, acrilato de butila e ácido metacrílico. As propriedades das dispersões híbridas resultantes foram avaliadas por espalhamento dinâmico de luz, teor de sólidos, pH e potencial Zeta. Os polímeros resultantes da secagem das dispersões aquosas foram caracterizados por cromatografia por exclusão de tamanho, calorimetria exploratória de varredura, análise dinâmico-mecânica, dureza, microscopia ótica do processo de cristalização, microscopia de força atômica, microscopia eletrônica de transmissão. A influência do método de síntese na morfologia dos híbridos foi avaliada. / PU-acrylic hybrids were prepared via emulsion polymerization, using an aqueous polyurethane dispersion as a seed for the acrylic monomers polymerization. Different quantities of acrylic monomers (butyl acrylate and methacrylic acid) were polymerized. The properties of the resulting hybrid dispersions were evaluated through dynamic light scattering, solid content, pH and Zeta potential. The resulting polymers obtained from dried dispersions were characterized via size exclusion chromatography, differential scanning calorimetry, dynamic mechanical analysis, optical microscopy of the crystallization process, atom force microscopy and transmission electron microscopy. The influence of the synthetic method on the morphology of the hybrids was evaluated.

Made available in DSpace on 2016-06-02T20:36:16Z (GMT). No. of bitstreams: 1 2035.pdf: 2216348 bytes, checksum: 3c9eeba4a9f95b09746c4737499e2dde (MD5) Previous issue date: 2008-08-22 / Universidade Federal de Sao Carlos / Some materials can be encapsulated with metals, inorganic solids and biomolecules, in a nanometric scale, to form a nanocomposite which has specific properties that can be open to research and technology works. In the literature, they are represented as core@shell. When silica particles are coated with a luminescent material, as the Eu2O3, the final material will have different properties from the core and the shell material. The silica used as a core in this work is the silica-germania VAD, synthesized by the Vapor-phase Axial Deposition (VAD) technique, which has been given by the PhD. Carlos K. Suzuki from FEM-UNICAMP. The luminescent properties of the Eu3+ ion in the SiO2-GeO2@Eu2O3 material, has been studied to get some information about the environment around this ion during the heat treatment process. The emission spectra of the samples presented the main Eu3+ characteristics 5D0→7FJ ( J= 0,1,2,3, 4) bands. The degradation of the polymeric shell which involves the Eu3+ ions degradation occurs as the temperature increases, causing structural changes around this ion. With its degradation, the Eu3+ ion is incorporated to the silica-germania matrix. The interaction between this ion and the matrix is through Ge-O-Eu linkages, which suppress the Eu3+ luminescence. The same luminescence behavior is observed for the SiO2@Eu2O3 and SiO2@Eu2O3 spherical samples heat treat in the same temperatures. The lifetime curves for these materials when they are excited in its respective maximum of emission and excitation, present a mono-exponential feature and the values are higher than Eu2O3 pure. This material presented some novel optical properties, which makes it in a potential candidate to be used in a photonic area. / Materiais quando encapsulados com metais, sólidos inorgânicos e biomoléculas, em escala nanométrica, formam um nanocompósito com propriedades específicas, que podem ser estendidas para diversas áreas da pesquisa e da tecnologia. Este material, na literatura, é designado como core shell ou core@shell. Quando a sílica é revestida com um material luminescente, como o Eu2O3, este material formado terá propriedades diferentes da sílica que constitui o núcleo e do Eu2O3 que constitui a nanocamada. Neste trabalho, a sílica utilizada no encapsulamento, foi a sílica-cermânia VAD, sintetizada pelo método Deposição por fase de vapor (VAD), que nos foi fornecida pelo Prof. Dr. Carlos K. Suzuki, da FEM - Unicamp. As propriedades luminescentes do íon Eu3+, no material SiO2-GeO2@Eu2O3 obtido, foram estudadas para se obter informações do ambiente em que este íon se encontra durante a calcinação do material. Os espectros de emissão das amostras obtidas apresentaram as bandas referentes às transições 5D0→7FJ (J= 0,1,2,3, 4), características do íon Eu3+. Com o aumento da temperatura, ocorre a degradação da camada polimérica que envolvia o íon Eu3+, causando mudanças estruturais ao seu redor. Com a sua degradação, o Eu3+ é incorporado á matriz de sílica. A interação deste íon com a matriz de sílica-germânia se dá através da formação de ligações Ge-O-Eu, que suprimem sua luminescência. O comportamento da luminescência deste íon foi semelhante ao observado nas amostras de SiO2@Eu2O3 e SiO2@Eu2O3 esférica tratadas nas mesmas temperaturas. As curvas de tempo de vida dos materiais quando excitados em seus respectivos máximos de emissão e excitação, apresentaram um comportamento monoexponencial e os valores são maiores quando comparados com o Eu2O3 puro. Este material apresentou algumas propriedades ópticas interessantes, que o torna um candidato em potencial para ser utilizado na área de fotônica.

Electrospinning or electrostatic fibre spinning employs electrostatic force to draw fibres from a liquid, either a polymeric solution or a polymer melt in the form of a charged jet. The jet solidifies and is deposited on a collector in the form of a non-woven fibrous mat. Electrospun fibres have diameters between several nanometres to a few microns, which is one of the main advantages of the process, as materials at the nanoscale have shown great potential in a wide range of healthcare and energy applications. The initial selection of solvents to dissolve the polymer for production of electrospun defect-free nanofibres has generally been based on experience from similar polymer-solvent systems. The selection of a solvent is important to control the fibre surface morphology that would eventually determine the field of application for the electrospun nanofibrous structures. However, little attempt has been made to study the correlation between the solubility behaviour of the polymer in different solvents and the electrospinnability of the polymer solutions. From this perspective, the first part of this thesis focused on the selection of different solvents for the production of poly (lactic acid) (PLA) nanofibres. Solution properties were measured and the electrospun nanofibrous structures were analysed in terms of morphology and nanofibre diameter. Understanding the molecular interactions between polymer and solvents enables the correct solvent selection to ensure the desired nanofibrous structure. Solubility is not the only criterion for nanofibre formation from a polymer solution. Polymer concentration is one of the main factors affecting electrospinning. For this reason, a relationship between PLA concentration and nanofibre morphology was determined by solution property measurements. A three step systematic methodology has been proposed in this thesis in order to select appropriate solvent and polymer concentration for the production of homogeneous electrospun mats made of defect-free nanofibres. This methodology was validated for PLA nanofibres, but it can be used for a wide range of polymers. It simplifies the solvent selection process and can significantly improve the trial and error approaches used at present. Despite several models for electrospinning having been proposed to predict the behaviour of the electrospun jet, there are no simple methods for a priori prediction of the final morphology of the electrospun mat from the knowledge of solution properties and electrospinning process parameters. Moreover the prediction of nanofibre diameter is still a difficulty and little research has been done on this. For these reasons, the second part of this thesis is dedicated to understanding the effect of some process parameters on the jet electric current and hence on the morphology of PLA nanofibres. The values of current measured were used to verify an equation proposed in the literature for the prediction of the final diameter. The experimental diameter of the PLA nanofibres was compared with the predicted value. In the last chapter coaxial electrospinning was employed to produce PLA nanofibres with a core shell structure for the incorporation of a model hydrophilic drug in the nanofibre core. The large surface area to volume ratio of nanofibres offers the great advantage of higher efficiency of encapsulation and better control of the release profile compared with other drug delivery systems. Even though successful encapsulation of drug and proteins have been reported, it is not clear how to verify the continuous drug distribution in the core throughout the whole length of the fibre. The solution properties of both core and shell strongly affect the outcome of the electrospinning process. For this reason, several techniques have been used to verify the formation of a core shell structure and proper encapsulation of the drug. In addition, the efficiency of drug encapsulation was evaluated and drug release studies were performed.

Nanoligas bimetálicas têm atraído a atenção de pesquisadores nas últimas décadas devido a possibilidade de ajustar suas propriedades físico-químicas, tais como propriedades elétricas, ópticas, magnéticas e de reatividade, por meio da variação do número de átomos, da composição química e do formato geométrico. As nanoligas bimetálicas que combinam Pt com outros metais são especificamente interessantes na área de catálise heterogênea, devido a possibilidade de se obter materiais com propriedades distintas de seus respectivos sistemas unários no que se refere ao surgimento ou aumento da atividade catalítica, à seletividade e, muitas vezes, ao preço reduzido. Esse trabalho tem como objetivo investigar as propriedades estruturais, energéticas, eletrônicas e de estabilidade de nanoligas bimetálicas core-shell de 55 átomos que combinam Pt com metais de transição (MT) pertencentes às séries de transição 3d, 4d e 5d dos grupos de Fe a Zn. Esses sistemas foram estudados utilizando cálculos de primeiros princípios (ab initio) baseados na teoria do funcional da densidade, tal como implementada no código computacional VASP (Vienna Ab initio Simulation Package). As nanoligas putativas de mínimo global energético (pGMC) de composição Pt13MT42 e Pt42MT13 calculadas nesse estudo apresentaram características particulares quanto à geometria e ao arranjo das espécies metálicas na nanoliga. Ao que diz respeito aos arranjos core-shell, foram observados dois arranjos em que a fica Pt no caroço (Pt13Ag42 e Pt13 Au42) e sete arranjos em que a Pt fica na superfície (Pt42Fe13, Pt42Co13, Pt42Ni13, Pt42Cu13, Pt42Ru13, Pt42Rh13 e Pt42Os13). Os mecanismos que levam à formação destas e das demais nanoligas pGMC foram investigados com base em três fatores: raio atômico, energia de superfície e cargas de Bader. Verificou-se que raio e a energia de superfície competem como fator determinante pelas posições preferenciais de cada espécie metálica na nanoliga. Nos casos em que houve divergência, o raio apresentou-se como o fator de maior importância, entretanto, quando o raio das espécies são muitos próximos, a energia de superfície exerce um papel de maior importância. A partir da análise de cargas de Bader, observou-se ocorrência de transferência de carga da região do caroço para a região da superfície para a maioria das nanoligas. No mais, observou-se que as nanoligas core-shell contam com atração coulômbica de maior magnitude do que as demais nanoligas pGMC, como resultado de altas cargas de sinal oposto em cada uma das regiões. / Bimetallic nanoalloys have been attracting attention since the last decades due to the possibility of adjusting their physical-chemical properties, such as electrical, optical, magnetic and reactivity properties, by means of the variation of the number of atoms, chemical composition and geometry. Bimetallic nanoalloys that combine Pt with other metals are especially interesting for heterogeneous catalysis given the possibility of obtaining materials with properties that differ from their respective unary systems regarding the appearance or increase of catalytical activity, selectivity and, in many cases, reduced cost. The aim of this work is the evaluation of the stability and of structural, energetic and electronic properties of 55 atom core-shell bimetallic nanoalloys that combine Pt with transition metals (MT) from the 3d, 4d, and 5d transition periods from Fe to Zn groups. These systems were studied using first principle (ab initio) calculations based on density functional theory, as implemented in the VASP (Viena Ab initio Simulation Package) computer code. The nanoalloys with Pt13MT42 and Pt42MT13 compositions which were observed as putative global minimum configuration (pGMC) presented unique characteristics regarding their geommetry and the arrangement of the different metals within the nanoalloy. Considering the core-shell nanoalloys, two arrangements in which Pt is located in the core were observed (Pt13Ag42 e Pt13 Au42) as well as seven arrangements with Pt in the surface (Pt42Fe13, Pt42Co13, Pt42Ni13, Pt42Cu13, Pt42Ru13, Pt42Rh13 e Pt42Os13). The mechanisms that lead to the formation of these and of the remaining pGMC nanoalloys were investigated considering three factors: atomic radius, surface energy and Bader charges. It was verified that atomic radius and surface energy compete directly for the determination of preferential sites for the atoms in the nanoalloy. When these two factors diverge, the atomic radius is the most important factor. However, when the radii of the species involved are similar, the surface energy becomes the determining factor. In addition, Bader charges analysis showed that, for most nanoalloys, the core is positively charged and the shell accumulates negative charge, indicating that charge is transfered from the atoms in the core to the ones in the surface. Besides, the core-shell nanoalloys have a higher coulombic attraction in comparison with others pGMC, due to high quantities of charge with opposite sign in each region.

L'étude de cette thèse est focalisée sur la compréhension des caractéristiques du transport dans des systèmes granulaires cœur - coquille (cobalt - cobalt oxyde). Nous avons étudié le comportement magnétique et de transport de notre système granulaire ferromagnétique/antiferromagnétique. Les agrégats de cobalt de 4 nm sont fabriqués par une source à pulvérisation magnétron et condensation en phase vapeur. Lorsque les agrégats sont oxydés pendant le dépôt ils adoptent une géométrie en cœur – coquille avec un cœur icosaédrique et une coquille CoO de structure cfc. Après le dépôt, les agrégats sont caractérisés par différentes méthodes. In situ, elles sont caractérisées en fonction de la quantité déposée par le spectromètre à temps vol. Ex situ, elles sont analysées par le SQUID (mesure magnétique) et par les mesures de transport. Plusieurs caractéristiques de nos échantillons ont été mises en évidence lors de l'analyse magnétique. Trois propriétés magnétiques nous intéressent principalement. La première est le couplage d'échange F/AF, étudié sur l'ensemble des agrégats de cobalt avec différents pourcentages d'oxydation (entre 33% de CoO et 95% de CoO). Nous avons constaté que l'effet maximum est obtenu pour l'échantillon le plus oxydé à cause de l'augmentation de la coquille d'oxyde. La deuxième propriété magnétique concerne la présence d'un superparamagnétisme modifié par l'interaction d'échange entre le cœur et la coquille. La troisième est l'effet de traînage qui se manifeste le plus souvent par une diminution du décalage d'échange et du champ coercitif après plusieurs mesures successives. Ce phénomène est dû à une instabilité de la configuration magnétique obtenue lors du refroidissement sous champ mais il est cependant difficile d'identifier l'origine exacte. Les propriétés de transport de notre système sont mises en évidence par l'étude de la résistivité, de la magnétorésistance et de la résistance du Hall en fonction de la température et du champ magnétique appliqué. La variation de la résistivité avec la température présente un minimum et qu'elle varie très peu avec la température. Ce comportent est typique des systèmes transitoires, se situant entre le régime métallique et le régime isolant. La faible magnétorésistance varie très peu avec la température. Son amplitude ne dépasse pas 0.1% dans tous les alliages granulaires mesurés. Le système étudié est caractérisé par une résistivité de Hall extraordinaire positive à toutes les températures de mesure. / This study is focused on understanding the transport properties of granular systems core - shell with emphasis on cobalt - cobalt oxide materials. We studied the magnetic and transport behavior of our granular system ferromagnetic/ antiferromagnetic. The cobalt clusters of 4 nm are obtained by a magnetron sputtering source and vapor phase condensation. The clusters oxidized during deposition adopt a core – shell geometry with icosahedra core and a fcc structure of CoO shell. After deposition, the clusters are characterized by different methods. In situ, they are characterized in terms of the amount of matter deposited by time flight spectrometer. Ex situ, they are analyzed by the SQUID (magnetic measurement) and transport measurements. Several characteristics of our samples have been identified during the magnetic analyses. Three magnetic properties are mainly interest. The first is the exchange bias F/AF, studied on the cobalt clusters with different oxidation percentages (between 33%CoO and 95% of CoO). We found that the maximum effect is obtained for the the oxidized samples due to the increased oxide shell size. The second magnetic property is the presence of superparamagnetism modified by the exchange interaction between the core and the shell. The third is the training effect shown often by a decrease in the exchange bias and coercive field after several successive measurements. This might be attributed to the instability of the magnetic configuration obtained upon cooling under a field, but it is difficult to identify the exact origin. The transport properties of our system are underlined by the study of the resistivity, magnetoresistance and Hall resistance as a function of temperature and applied magnetic field. The variation of resistivity with temperature shows a minimum. In the same time this variation is small as a function of the temperature. This behavior is associated with the transition systems which are found between the metallic and insulator regime. The variation of the magnetoresistance with temperature is small. Its amplitude does not exceed 0.1% in all granular alloys measured. The studied system is characterized by a positive extraordinary Hall resistivity at all temperatures of measurement.

Made available in DSpace on 2015-05-14T13:21:40Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 3260499 bytes, checksum: 5bc01451ca6efdedd221c478c2647b55 (MD5) Previous issue date: 2014-08-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The need to control textile effluents due to contamination of rivers has led CONAMA to regulate and require a more efficient treatment process. Among the methods of treatment, heterogeneous catalysis stands out due to its high efficiency. The most used photocatalyst is TiO2. The combination of this material with other ones has been employed to improve its activity and/or its performance. Several systems have been tested, including the core-shell that constitutes a complete coverage of one material by another. In this work, TiO2@CoFe2O4 was synthesized by the modified-Pechini method with the addition of CoFe2O4 nanoparticles into the polymeric resin containing titanium. A magnetic material was obtained, which was characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), ultraviolet - visible spectroscopy (UV-Vis), specific surface area by the BET method. The materials were applied in the photodiscoloration of an azo dye. The pure TiO2 calcined at 700 °C showed a mixture of phases anatase / rutile in the proportions 77/23%, which was the calcination temperature which led to the highest photocatalytic activity in the discoloration of the solution yellow gold remazol (RNL). A discoloration of 81% in color of the solution was attained after 6 h of exposure to UV light, while 94% was reached after 2 h of irradiation with sunlight. With the core@shell system CoFe2O4@TiO2 synthesized with 90 % of TiO2, a mixture of anatase and rutile of 92 : 8% was obtained for a calcination temperature of 500 °C. This material showed 76% discoloration after 16 h of exposure to UV light under the same conditions used for the test with pure TiO2 / A necessidade do controle de efluentes têxteis devido à contaminação de águas fluviais tem levado órgãos como o CONAMA a regulamentar e exigir um processo de tratamento mais eficiente. Dentre os métodos de tratamento estudados, os Processos Oxidativos Avançados (POA) têm demonstrado grande eficiência, como na fotocatálise heterogênea utilizando materiais semicondutores, sendo o TiO2 um dos mais empregados. A combinação deste material com outros tem sido estudada com o objetivo de melhorar a atividade e/ou performance do mesmo. Para isso vários sistemas têm sido utilizados, dentre eles o core@shell, que consiste na completa cobertura de um material por outro. Neste trabalho o CoFe2O4@TiO2 foi sintetizado pelo método Pechini modificado, com a adição do CoFe2O4 nanoparticulado à uma resina polimérica de titânio, sendo obtido um material magnético, o qual foi caracterizado por difração de raios X (DRX), espectroscopia infravermelho (IV), espectroscopia na região ultravioleta e visível (UV-Vis), análise de área superficial específica pelo método de BET. Os materiais foram testados na fotodegradação de um corante azo. O TiO2 puro calcinado a 700 ºC, apresentou mistura de fases anatase / rutilo com proporção 77 / 23 %, sendo a temperatura de calcinação que levou à maior atividade fotocatalítica na descoloração da solução de amarelo ouro remazol (RNL). Foi obtida 81 % de redução da cor da solução em 6 h de exposição a luz UV e 94 % após 2 h com irradiação de luz solar. Com o sistema core@shell CoFe2O4@TiO2 sintetizado com 90 % de TiO2 foi obtida uma mistura de 92 % de anatase e 8 % de rutilo, para uma temperatura de calcinação de 500 ºC. Este material levou a 76 % de descoloração em 16 h de exposição à luz UV com as mesmas condições utilizadas para o teste com o TiO2 puro

Híbridos poliuretano-acrílicos foram sintetizados via polimerização em emulsão, utilizando uma dispersão de poliuretano base poliol poliéster como semente para a polimerização dos monômeros acrílicos, no caso, acrilato de butila e ácido metacrílico. As propriedades das dispersões híbridas resultantes foram avaliadas por espalhamento dinâmico de luz, teor de sólidos, pH e potencial Zeta. Os polímeros resultantes da secagem das dispersões aquosas foram caracterizados por cromatografia por exclusão de tamanho, calorimetria exploratória de varredura, análise dinâmico-mecânica, dureza, microscopia ótica do processo de cristalização, microscopia de força atômica, microscopia eletrônica de transmissão. A influência do método de síntese na morfologia dos híbridos foi avaliada. / PU-acrylic hybrids were prepared via emulsion polymerization, using an aqueous polyurethane dispersion as a seed for the acrylic monomers polymerization. Different quantities of acrylic monomers (butyl acrylate and methacrylic acid) were polymerized. The properties of the resulting hybrid dispersions were evaluated through dynamic light scattering, solid content, pH and Zeta potential. The resulting polymers obtained from dried dispersions were characterized via size exclusion chromatography, differential scanning calorimetry, dynamic mechanical analysis, optical microscopy of the crystallization process, atom force microscopy and transmission electron microscopy. The influence of the synthetic method on the morphology of the hybrids was evaluated.

Le travail décrit dans cette thèse est basé sur la synthèse et l’étude de nanoparticules cœur-coquille capables de capter du césium radioactif. Ces travaux s’inscrivent dans l’amélioration d’un procédé de sorption du césium déjà existant et utilisant des monolithes de silice poreux fonctionnalisés avec des nanoparticules (NPs) d’Analogue du bleu de Prusse (ABP) ou plus précisément K2CuFe(CN)6 (CuABP). Les nanoparticules issues de cette famille sont très connues pour leur capacité de sorption et leur sélectivité vis-à-vis du césium. Ainsi afin d’éviter l’agrégation des NPs au sein du monolithe et d’augmenter les capacités de sorption, il a été décidé de synthétiser des nanoparticules cœur-coquille avec un cœur d’ABP protégé par une coquille de silice poreuse. La voie de synthèse choisie pour réaliser ce type de nanoparticules est celle qui utilise une microémulsion inverse afin de contrôler la forme et la taille des nanoparticules finales. Ce choix a permis de réaliser la synthèse in situ des NPs d’ABP avec une excellente stabilité des nanoparticules dans les gouttes d’eau dans certaines conditions opératoires. Les microémulsions ont été caractérisées grâce aux SAXS (Small Angle X-ray Scattering). Grâce à des modèles de simulation, des tailles de gouttes d’eau allant de 0.5 à 3 nm de rayon ont été déterminées selon la quantité d’eau introduite. Le paramètre w correspondant au rapport molaire entre l’eau et le tensioactif (w=[H2O]/[tensioactif]) es un bon moyen d’exprimer la quantité d’eau présente dans le système. La croissance de la coquille de silice est réalisée grâce au procédé sol-gel en milieu basique en présence de TEOS. La morphologie des nanoparticules cœur-coquille a ensuite été étudiée grâce à la microscopie électronique (HRTEM/STEM/HAADF) et l’analyse chimique et structurale a été réalisée grâce à la spectroscopie infrarouge (FTIR-ATR) et à la DRX. Ainsi, pour la première fois, des nanoparticules cœur-coquille telles que définies ici ont été synthétisées. Des tests de sorption du césium par ces nanoparticules cœur-coquille ont également été mis en œuvre avec des résultats encourageants (Qmax(NPs cœur-coquille)=125 mg/g). De plus ces nanoparticules ne sont pas seulement utiles pour la décontamination d’effluents aqueux, elles ouvrent aussi de nouvelles portes pour l’auto-irradiation et l’auto-confinement de radioéléments. / The research work described below is based on the synthesis and the study of core-shell nanoparticles able to entrap radioactive cesium. A sorption process of radionuclides on porous silica monoliths has already been described to capture radioactive cesium and to anchor it on a solid phase. Those materials were therefore functionalized with Prussian Blue Analogous (PBA) nanoparticles or more precisely K2CuFe(CN)6 (CuPBA) that are well known to be highly selective towards Cs. However, those materials did not allow optimal Cs sorption because of strong aggregation of PBA nanoparticles within the monoliths. Thereby, the solution developed is the use of core-shell nanoparticles in order to avoid the PBA aggregation. The core of these nanoparticles is made with PBA and protected by a porous silica shell.A reverse microemulsion is chosen as main synthetic route to synthesize and control the size and shape of these nanoparticles. That synthetic route allows in-situ synthesis of CuPBA nanoparticles in the microemulsion with an excellent stability of the particles in the water droplets. Microemulsions, characterized with SAXS, show droplets radius varying from 0.5 to 3 nm with regard to the water content defined by w parameter (w=[H2O]/[surfactant]). The growth of the silica shell is then achieved after the synthesis of CuPBA, using a classical basic conditions sol-gel process. The morphology of the core-shell nanoparticles is controlled with HRTEM/STEM-HAADF and the structural and chemical analysis are followed by XRD and FTIR-ATR. Finally, this study enables, for the first time, the synthesis of these core-shell nanoparticles. Then, recent sorption experiments highlighted that these core-shell nanoparticles can be used to entrap cesium with interesting capacity ((Qmax(core-shell NPs)=125 mg/g)). Moreover, these nanoparticles are useful for decontamination process and they open the way in the study of the self-irradiation and self-containment of radionuclides.