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Materiais híbridos orgânico-inorgânico: espécies de interesse farmacológico imobilizadas em hidróxidos duplos lamelares / Organic-inorganic hybrid materials: species of pharmacological interest immobilized into layered double hydroxideCunha, Vanessa Roberta Rodrigues da 20 December 2012 (has links)
A intercalação de espécies com atividade farmacológica em Hidróxidos Duplos Lamelares (HDLs) vem sendo explorada com uma maior freqüência não apenas pelo fato da matriz ser biocompatível, mas também por outros efeitos reportados em estudos recentes como: (i) possível liberação sustentada da droga mediada por alterações no pH, (ii) aumento da solubilidade de substâncias pouco solúveis em água, (iii) aumento da estabilidade química de substâncias frente à luz, ao calor, à umidade, ao oxigênio molecular etc. O principal objetivo deste trabalho é a intercalação de substâncias de interesse medicinal (em suas formas aniônicas) como a pravastatina, Prav (ação anti-hiperlipidêmica) e os antioxidantes ácidos coumárico, Cou, e lipóico, Lip, em HDLs de magnésio-alumínio e zinco-alumínio através da coprecipitação, utilizando diferentes condições experimentais (pH, tratamento pós-síntese e relação molar ânion/Al3+). As amostras sólidas foram caracterizadas por análise elementar (CHN e metais), difratometria de raios X, métodos espectroscópicos (vibracional no infravermelho, Raman e ressonância magnética nuclear de 13C no estado sólido), análise térmica, microscopia eletrônica de varredura, medidas de tamanho de partícula e de potencial Zeta. A ação farmacológica dos HDLs de composição Mg2Al foi investigada através do teste biológico com o corante Sulforodamina B na linhagem celular de melanoma A-375. A utilização de diferentes proporções molares Pravastatina/Al3+ (1, 2 e 3) não alterou significativamente a quantidade de substância orgânica presente no material. O HDL de composição lamelar Zn2+/Al3+ apresentou maior cristalinidade e maior quantidade de orgânico (52 % m/m) que a matriz Mg2+/Al3+ (32 % m/m). A Pravastatina forma uma bicamada na região interlamelar. Os valores de tamanho médio de partícula e do potencial Zeta encontrado para o material Mg2Al1Prav (razão molar Prav/Al3+= 1) são 126 nm e + 22,9 mV, respectivamente. A Pravastatina e o material de Mg2Al1Prav diminuíram o crescimento celular da linhagem A-375 em até 20 % após tratamento. A composição dos HDLs intercalados com íons coumarato é dependente da razão molar Cou/Al3+ empregada na síntese. Observou-se novamente que o emprego da composição lamelar Zn2+/Al3+ contribui para a obtenção de material com maior cristalinidade e quantidade de orgânico intercalado (36 % m/m) comparado ao análogo de Mg2+/Al3+ (32 % m/m). Os ânions orgânicos na forma bivalente, constatados pelos resultados obtidos no espectro Raman, assumem um arranjo de monocamada com inclinação do esqueleto carbônico em relação às lamelas. Dados de análise elementar e análise térmica sugerem que o íon orgânico está enxertado/coordenado às lamelas do HDL. A suspensão aquosa do material Zn2Al3Cou apresenta estabilidade moderada frente à aglomeração (potencial Zeta igual a + 39,6 mV) e tamanho médio de partícula de 226 nm. No caso dos HDLs-Lip, observou-se que o excesso de íons lipoato na síntese, assim como o tempo de agitação pós-síntese , não alterou a cristalinidade e a quantidade de orgânico (39 % m/m) no material. Os ânions orgânicos devem se organizar na forma de uma bicamada interdigitada na região interlamelar. A suspensão aquosa do material Mg2Al1Lip apresenta estabilidade moderada frente à aglomeração (potencial Zeta igual a + 34,3 mV) e tamanho médio de partícula de 110 nm. / The intercalation of species with pharmacological activity in Layered Double Hydroxide (LDHs) has been explored frequently not only because it is biocompatible, but also by others effects as reported in recent studies: (i) sustained release of the drug by changes in pH, (ii) increasing the solubility of poorly water soluble substances, (iii) increase of the chemical stability of substance against light, heat, moisture, molecular oxygen etc. The main goal of this work is the intercalation of substances of therapeutic interest (in their anionic forms) as Pravastatin, Prav (antihyperlipidemic), and the antioxidants coumaric acid, Cou, and lipoic acid, Lip, in LDHs of magnesium-aluminum and zinc-aluminum by coprecipitation using different experimental conditions (pH, post-synthesis treatment and molar ratio anion/Al3+). Solid samples were characterized by elemental analysis (CHN and metals), X-ray diffraction, spectroscopic methods (Vibrational Infrared, Raman and Nuclear Magnetic Resonance of 13C in solid state), thermal analysis, scanning electron microscopy, measurements of particle size and Zeta potential. The pharmacological activity of LDHs of Mg2Al composition was investigated by the biological assay with the dye Sulforhodamine B in the melanoma cell line A-375. The usage of different molar ratio Pravastatin/Al3+ (1, 2 and 3) did not significantly alter the amount of organic substance present in the inorganic carrier. The LDH of composition Zn2+/Al3+ promoted an increase in the crystallinity of the material and in the amount of organic (52 % w/w) compared to the Mg2+/Al3+ material (32 % w/w). Pravastatin forms a bilayer into the interlayer region. The mean particle size and Zeta potential of the Mg2Al1Prav (molar ratio Prav- /Al3+= 1) are 126 nm and + 22.9 mV, respectively. The Pravastatin and the material Mg2Al1Prav decreased cell growth of strain A-375 melanoma by 20 % after treatment. The composition of the LDH intercalated with coumarate ions is dependent of the molar ratio anion/Al3+ used in the synthesis. The composition Zn2+/Al3+ promoted an increase in the crystallinity and amount of the organic (36 % w/w) compared to Mg2+/Al3+ material (32 % w/w). The organic divalent anions, visualized by the Raman spectra results, assume a monolayer arrangement with the inclination of the carboxylate group related to the layer. Elemental and thermal analysis suggest the grafting/coordination of the organic ions into the layers of LDH. The aqueous suspension of the Zn2Al3Cou shows moderate stability against agglomeration (Zeta potential value + 39.6 mV) and particle size of 226 nm. In the case of LDHs-Lip, it was observed that excess of lipoate ions from the synthesis, as well as, the stirring time pos-synthesis did not alter the crystallinity and the organic amount (39 % w/w) material. The organic anions are organized in an interdigitated bilayer into the interlayer region. The aqueous suspension of the Mg2Al1Lip material shows moderate stability against the agglomeration (zeta potential value equal to + 34.3 mV) and a particle size of about 110 nm.
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Preparação e caracterização de hidróxidos duplos lamelares intercalados com espécies macrocíclicas metaladas / Preparation and characterization of layered double hydroxides intercalated with metallated macrocyclic speciesBarbosa, César Augusto Sales 08 July 1999 (has links)
O presente trabalho tem como objetivo a síntese e caracterização de hidróxido duplo lamelar (HDL) do tipo hidrotalcita intercalado com metaloftalocianinas (CuPcTs e CoPcTs) e metaloporfirina (CoTPhsP) aniônicas. Como rota sintética, três métodos foram testados: (i) coprecipitação do hidróxido duplo em solução contendo o macrociclo; (ií) reconstituição estrutural da mistura de óxidos obtida pela decomposição térmica de HDL na forma carbonato e (ííi) decomposição térmica do carbonato intercalado empregando um meio contendo poliol. A influência do método de intercalação nas propriedades texturais do material e o efeito da imobilização dos macrociclos na região interlamelar foram avaliados através da caracterização textural (difração de raios-X e medidas de área superficial), espectroscópica (vibracional no infravermelho, eletrônica no UV/visível e ressonância paramagnética eletrônica) e das análises elementar (C, H, N e metais) e termogravimétrica. Avaliou-se a influência das propriedades texturais dos compósitos e do arranjo dos intercalados na reatividade e estabilidade dos macrociclos confinados no espaço interlamelar através da reação de decomposição do peróxido de hidrogênio. A síntese por coprecipitação dos hidróxidos duplos lamelares do tipo hidrotalcita mostrou-se eficiente para a obtenção de produtos puros e de alta cristal inidade. Entretanto, os materiais obtidos a partir da intercalação dos macrociclos nas matrizes de HDL através dos diferentes métodos sintéticos resultaram em sólidos com baixa cristalinidade. Os estudos mostraram que a obtenção de materiais contendo apenas uma fase é dependente do método de intercalação empregado. Os resultados de análise elementar indicaram um alto grau de intercalação dos macrociclos nos HDLs. Os espectros vibracionais no infravermelho apresentaram bandas que podem ser atribuídas à presença de íons carbonato no espaço interlamelar dos sistemas HDL-macrociclos. A incorporação completa do macrociclo foi observada para a CoPcTs intercalada no HDL via método da coprecipitação. Por outro lado, o método do poliol, utilizado para a intercalação da CuPcTs e CoPcTs, resultou em materiais com baixo grau de intercalação. A intercalação dos macrociclos nos HDLs foi confirmada através dos resultados obtidos por difração de raios-X, que indicaram um aumento substancial do espaçamento basal, que aumentou de aproximadamente 8A nas matrizes precursoras contendo CO32- para cerca de 23A nas matrizes contendo os macrociclos intercalados. As medidas de área superficial sugerem que não houve a formação de microporos nos HDLs incorporados com os macrociclos, pois estes não apresentaram valores de área superficial significativamente maior que os das matrizes de HDL na forma carbonato. A intercalação da CoPcTs e da CoTPhsP aumenta tanto a estabilidade térmica dos HDLs em relação à matriz com carbonato, quanto a dos próprios macrociclos. Em relação aos HDLs contendo a CuPcTs, observou-se comportamento térmico distinto. A intercalação da CuPcTs também aumenta a estabilidade térmica do HDL mas o confinamento do macrociclo provoca a sua decomposição em temperatura menor que aquela observada quando livre. Os espectros de absorção eletrônica mostraram que as metaloftalocianinas quando intercaladas nos HDLs apresentaram menor grau de agregação às espécies livres. Porém, os espectros de RPE indicaram que as espécies CuPcTs agregados são dominantes nas amostras intercaladas uma vez que apresentam apenas valor de g isotrópico (g=2,06). Os sistemas com a CoPcTs também apresentaram agregados mas em menor extensão que aqueles com os análogos de Cu(II). Com relação ao comportamento catalítico dos diferentes materiais sintetizados na decomposição do peróxido de hidrogênio, os três macrociclos estudados apresentaram comportamentos distintos. A CuPcTs suportada e intercalada no HDL não apresenta atividade catalásica embora a forma livre promova a dismutação do H2O2. Os materiais com a CoPcTs e CoTPhsP são mais ativos que o macrociclo livre na decomposição do peróxido de hidrogênio. Os HDLs com a CoTPhsP são mais resistentes ao ataque oxidativo do peróxido de hidrogênio que a porfirina livre. As ftalocianinas metaladas em meio homogêneo ou heterogêneo não são degradadas pelo H202. Preparation and characterization of layered double hydroxides intercalated with macrocyclic metallated species / The aim of the present work is to synthesize and characterize layered double hydroxides (hydrotalcite-like compounds) intercalated with anionic metallophthalocyanines (CuPcTs and CoPcTs) and metalloporphyrin (CoTPhsP). Three preparative methods were tested to isolate the intercalated materiais: (i) double hydroxide coprecipitation in the presence of the macrocycle, (ii) structure reconstruction of the mixed oxides obtained by thermal decomposition of layered double hydroxide (LDH) phase containing volatile ion; (iii) thermal decomposition of carbonate-containing phase in a polyol media. The influence of the intercalation method in the material textural properties and the effect of the macrocycle immobilization in the interlayer region were evaluate through the textural characterization (x-ray diffraction analysis and surface area measurements), vibrational (IR) and electronic (UV-visible) spectroscopy, elementary analysis and thermogravimetry. The effect of the composites textural properties and the intercalated species arrangement in the LDH gallery was evaluate carrying out the hydrogen peroxide decomposition reaction. The LDHs preparation by coprecipitation was an efficient method to obtain pure and crystalline products. However the macrocycle intercalated materiais isolated by the three methods mentioned above were poorly crystallized phases. The experimental data also showed that the isolation of materiais containing only one phase depends on the synthetic approach. The extension of intercalated macrocycle species in LDHs was broad as judged by elementary analysis data. The IR vibrational spectra showed some bands that can be attributed to the presence of carbonate ions in the interlayer of LDH macrocycle systems. Material containing approximately 100% of macrocycle in the LDH gallery was isolated by the double hydroxide coprecipitation in a solution containing CoPcTs. On the other hand, polyol method rendered materiais with small amount of intercalated metallophthalocyanines. The macrocycle intercalation between LDHs layers was confirmed by the x-ray diffraction patterns: the basal spacing of the carbonate precursor (ca. 8A) increases to approximately 23A in the matrices intercalated with phthalocyanines or porphyrin. The surface area data suggested that the macrocycle intercalated solids do not have microporous owing to the fact that as the surface area values are not higher than that obtained for the LDH precursor. CoPcTs and CoTPhsP intercalation increases the thermal stability of HDLs in relation to the carbonate phase as much as the macrocycle stability. CuPcTs systems showed a particular behaviour: the thermal stability of LDH structure is increased but the phthalocyanine decomposition occurs in a lower temperature than that observed to the macrocycle free form. The electronic absorption spectra revealed a decrease in the metallophthalocyanine aggregation when the species are intercalated in LDHs However the EPR spectra showed only the isotropic g value (g=2.07) evidencing that the CuPcTs aggregated species are dominant in the LDH samples. CoPcTs systems are also aggregated but in a less extension than the Cu(lI) compound. The catalase-like activity of the intercalated materiais was distinct for each macrocycle system tested. CuPcTs intercalated or supported in LDHs is not active in the hydrogen peroxide dismutation in despite of the free form shows activity. CoPcTs and CoTPhsP materiais exhibit better catalytic performance than the free macrocycles. LDHs containing CoTPsP are more resistant to the oxidative attack of hydrogen peroxide than the free porphyrin. Metallophthalocyanines species in homogeneous or heterogeneous media are not degraded by H202.
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O papel da argila na estabilização termica de nanocompositos : um estudo da ordem locale a média distância / Rôle de l’argile dans la stabilisation thermique de nanocomposites : étude de l’ordre local et de l’ordre à moyenne distance / Role of clays in the thermal stabilization of nanocomposites : study at the short and medium range orders.Pereira de Carvalho, Hudson Walace 26 March 2012 (has links)
Une des manières d'augmenter la stabilité thermique de polymères consiste à leur ajouter de faibles quantités d'argile dispersées dans échelle nanométrique. De tels matériaux sont appelés de « nanocomposites ». Il existe plusieurs explications à ce phénomène, comme les effets de barrière de diffusion et la formation de charbon. D’autres sont en cours de vérification, comme les effets de piégeage de radicaux par les ions qui participent à des réactions de type Fenton. Notre objectif a été de suivre in situ des transformations chimiques de la phase argile, afin de mieux comprendre comment ces nanostructures lamellaires retardent la décomposition de polymères. Pour ce faire, trois types de nanocomposites ont été préparés: i) Poly(méthylméthacrylate)-co-Poly(trimetoxysilil propyl méthacrylate) et argiles montmorillonite (MMT) du type Cloisite (PMMA-co-PTMSM-Cloisite); ii) PMMA-argiles montmorillonites naturelles contenant différents taux d’ions Fe3+ dans les couches octaédrique (PMMA-MMT); iii) PMMA-hydroxydes doubles lamellaires (HDL), avec différentes proportions d’ ions Zn2+ , Cu2+ et Fe3+ PMMA-HDL. La thermo-décomposition des argiles primitives et de leurs nanocomposites ont été suivies par des analyses thermiques, de diffusion de rayons X (SAXS et WAXS) et par spectroscopie d'absorption de rayons X (EXAFS). Les effets de l'atmosphère, de la composition chimique des lamelles, et de la quantité d'argile employée dans l'obtention des nanocomposites ont été évalués. L'étude des nanocomposites, PMMA-co-PTMSM-Cloisite a mis en évidence deux mécanismes de stabilisation. Elle a montré que l'addition d’argiles résulte en une stabilisation plus importante sous atmosphère d'air, que sous atmosphère de N2, et est aussi plus importante selon la quantité d'argile dispersée dans le polymère. La formation de charbon a aussi été observée seulement sous l'atmosphère d'air. La stabilité thermique des nanocomposites PMMA-MMT est aussi proportionnelle à la quantité d'argile employée dans l'obtention de la nanocomposite. Pour de faibles quantités d’argile, 0.3-1 % en masse, la stabilité thermique des nanocomposites est proportionnelle à la quantité de ions Fe3+ présents dans l'argile. Le suivi de l'environnement chimique des ions Fe3+ par EXAFS en fonction de la température, a montré que quand la phase argile est dispersée dans le PMMA, les ions Fe3+ sont réduits à Fe2+, ce qui ne se vérifie dans les phases primitives. Ces mécanismes de stabilisation indiquent que la phase argile stabilise le PMMA par des mécanismes de barrière de diffusion et par le piégeage des radicaux. Les nanocomposites PMMA-HDL contenant des ions Fe3+ sont plus stables que ceux qui contiennent des ions Cu2+. L’étude in situ de 'évolution de l'ordre local à moyenne distance en fonction de la température a montré que les phases HDL stabilisent le PMMA également par les mécanismes de barrière de diffusion et le piégeage de radicaux. L’ion Cu2+, induisant des distorsions dans l'ordre local, rend les lamelles moins stables : elles se décomposent à des températures inférieures, et l'effet de barrière de diffusion est alors réduit. Par contre, les ions Cu2+ et Fe3+ piègent des radicaux de la phase polymérique qui se décomposent et ralentissent le phénomène. Cette thèse démontre que les argiles peuvent agir comme des particules réactives ou inertes, c'est-à-dire, à travers des réactions chimiques avec le polymère ou comme barrière physique. La stabilisation thermique des polymères dépend d’une combinaison de mécanismes, parmi eux la barrière de diffusion, la formation de charbon et le piégeage de radicaux. / One way to increase thermal stability of polymers consists by mixing them with a few amount of clays (< 1 % w/w), spread at a nanometric scale. Such materials are called ‘nanocomposites’. Many explanations of the phenomenon have been given, as diffusion barrier effects, the formation of char. Others being checked, as the effects of radical trapping by the ions involved in Fenton-type reactions. In this work, the main objective was to follow in situ the chemical transformations of the clay phase, in order to better understand how these lamellar nanostructures retard the polymer decomposition. Three types of nanocomposites were prepared : i) Poly(methyl methacrylate)-co-Poly(trimetoxysilil propylmethacrylate) and montmorillonite clay (MMT) type Cloisite (PMMA-co-PTMSM-Cloisite); ii) natural PMMA-montmorillonites clay with different proportion of ions Fe3+ in octahedral layers (PMMA-MMT); iii) PMMA- double-layered hydroxides (HDL), with different rate of ions Zn2+, Cu2+ and Fe3+ PMMA-HDL. The thermal decomposition of primitive clay and of its respective nanocomposites were followed by thermal analysis, X-ray scattering (SAXS and WAXS) and X-ray absorption spectroscopy (EXAFS). The effects of atmosphere, the chemical decomposition of layers and the clay amount employed to obtain the nanocomposites were evaluated. The study of nanocomposites, PMMA-co-PTMSM-Cloisite showed that the addition of clay, under air, results in a greater stabilization than under N2 atmosphere, which is also higher according to the amount of clay spread in the polymer. The formation of char has been observed only under air atmosphere. It highlighted two stabilization mechanism: char formation and diffusion barrier. The thermal stability of nanocomposites PMMA-MMT is also proportional to the amount of clay used in obtaining the nanocomposite. For small amount of clay, 0,3 – 1wt%, the thermal stability of nanocomposites is proportional to the quantity of ions Fe3+ in the clay. The monitoring of the chemical environment of the ions Fe3+ by EXAFS in function of the temperature showed that, when the inorganic phase is spread in the PMMA, the ions Fe3+ are reduced to Fe2+. This was not verified in the pristine phases. The stabilization mechanisms revealed in this study, indicate that the clay phase stabilizes the PMMA by diffusion barrier mechanisms and radical trapping. The nanocomposites PMMA-HDL with ions Fe3+ are more stable than those containing ions Cu2+. The in situ study of the evolution of the local order at middle-range distance in function of temperature showed that the HDL phases stabilize also the PMMA by diffusion barrier mechanisms and the radical trapping. The ion Cu2+ , leading to distortions at the local order, makes layers less stable; they decompose at lower temperature and the diffusion barrier effect is then reduced. On the other hand, the ions Cu2+ and Fe3+ trap radicals in the polymer phase which breaks down and slow the phenomenon. This PhD work demonstrates that clay can act as reactive or inert particles, i.e. through chemical reaction with the polymer or as physical barrier. The thermal stabilization of polymers relies on a mechanism combination; whom the diffusion barrier, the char formation and the radical trapping.
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Composition, structure et comportement électrochimique d'Hydroxydes Doubles Lamellaires au cobalt : vers des applications en tant que matériaux d'électrodes / Composition, Structure and electrochemical behaviour of cobalt-containing Layered Double Hydroxides : towards applications as electrode materialsVialat, Pierre 02 October 2014 (has links)
Les Hydroxydes Doubles Lamellaires (HDL) sont des matériaux en couches à forte potentialité pour de nombreux domaines d’applications, cependant, leur caractère d’isolants électriques limite les possibilités d’applications en électrochimie. Il est donc intéressant de chercher des moyens d’améliorer leurs propriétés conductrices. Dans ce but, trois approches ont été envisagées : - l’insertion de cations de métaux de transition 3d dans les feuillets, - l’intercalation de médiateurs redox entre les feuillets ou - l’ajout de percolant électronique dans le système afin d’obtenir des HDL « électroactifs ». Même si les combinaisons possibles de cations divalents et trivalents dans le feuillet HDL sont nombreuses, toutes les études ont été centrées sur le rôle d’un élément principalement, le cobalt. La composition chimique des matériaux ainsi que leurs propriétés physico-chimiques en termes de morphologie et de structure globale et locale ont été étudiées par le couplage de différentes techniques d’analyse (DRX, IRTF, MEB, ATG, XAS, PDF, XPS) avant de réaliser la caractérisation des propriétés électrochimiques par voltammétrie cyclique et spectroscopie d’impédance électrochimique. Ces analyses ont alors montré les potentialités applicatives de certaines compositions des matériaux HDL choisis. Les propriétés capacitives des phases CoIICoIII-CO3 ont été étudiées pour une utilisation en tant que matériaux d’électrodes de supercondensateurs alors que la présence d’un médiateur redox ainsi que les propriétés d’immobilisation d’enzymes de la phase hybride Co2Al-ABTS ont permis d’élaborer des bioélectrodes potentiellement adaptables dans une biopile. / Layered Double Hydroxides (LDH) are lamellar materials with strong potentiality for numerous fields of application, however, their insulating electric character limits the possibilities for electrochemical applications. It is thus necessary to investigate for ways to improve their conductive properties. In this purpose, three approaches were envisaged: - insertion of cations of 3d transition metals into the lamellar sheets, - insertion of redox mediators between the layers or - addition of electronic percolants in the system to obtain “electroactive” LDH. Even if the possibilities of combination of divalent and trivalent metal cations within the LDH layer are tunable, all the studies were centered on the role of an element mainly, the cobalt. The chemical compositions of materials as well as their physico-chemical properties, in terms of morphology and global and local structure, were then studied by coupling various analytical techniques before realizing the characterization of the electrochemical properties by cyclic voltammetry and electrochemical impedance spectroscopy. These analyses then showed the application potentialities of certain type of LDH materials. The capacitive properties of CoIICoIII-CO3 phases were studied as supercapacitor electrode materials while the presence of a redox mediator as well as the immobilization properties for enzymes of the hybrid phase Co2Al-ABTS allowed constructing bioelectrodes potentially applicable in biofuel cell.
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Síntese e caracterização de nanocompósitos do tipo polímero/silicatos lamelares com propriedades anisotrópicas via polimerização RAFT em emulsão / Synthesis and characterization of polymer/layered silicate nanocomposites with anisotropic properties via RAFT emulsion polymerizationSilva, Rafael Caetano Jardim Pinto da 27 September 2013 (has links)
Nos últimos anos, a incorporação de partículas inorgânicas em uma matriz polimérica com a finalidade de se obter sistemas híbridos orgânico/inorgânico utilizando diferentes técnicas de polimerização tem recebido grande atenção. Neste sentido, preservar e controlar as propriedades físico-químicas das partículas inorgânicas torna-se essencial para manter a integridade destas em nanoescala, bem como para obtenção de dispersões uniformes, magnificando os efeitos de reforço e demais ganhos de propriedades desejadas para a matriz polimérica. Quando se utiliza partículas inorgânicas anisotrópicas tais como a montmorilonita, silicato lamelar mais utilizado para obtenção de nanocompósitos do tipo polímero/silicato lamelar, este controle apresenta-se como um problema particularmente desafiador. Nesse contexto, a polimerização radicalar controlada (PRC) vem se destacando como uma importante via para atingir os objetivos mencionados acima, encontrando-se na literatura diversas estratégias de síntese em meio a solventes orgânicos na qual a efetiva nanoencapsulação de partículas inorgânicas dá-se por meio do crescimento de cadeias poliméricas na superfície destas estruturas inorgânicas. Entretanto, poucos trabalhos são encontrados envolvendo rota de obtenção semelhante em meio aquoso, tais como suspensão, emulsão e miniemulsão, processos estes que possuem grande interesse industrial, ambiental e viabilidade real de ampliação de escala quanto à produção.Desta forma, o objetivo deste projeto de pesquisa concentra-se na síntese e na caracterização de nanocompósitos do tipo polímero/silicato lamelar via polimerização radicalar controlada em emulsão. As polimerizações radicalares controladas de estireno em emulsão, via mecanismo de transferência reversível de cadeia por adição-fragmentação (RAFT), foram conduzidas na presença de argila montmorilonita (MMT) e mediadas por dois macroagentes de transferência de cadeia com grupo funcional tri-tioéster, sendo o primeiro constituído de cadeia polimérica não iônica de monoetil éter de poli(etilenoglicol) (MPEG-CPP) e outro derivado do MPEG-CPP contendo adicionalmente um bloco ionizável de poli(ácido metacrílico) incorporado à cadeia polimérica (MPEG-b-PMAA-CPP). Foram avaliados inicialmente os parâmetros de adsorção dos macroagentes MPEG-CPP e MPEG-b-PMAA-CPP na superfície da MMT bem como a influência das variáveis do processo de polimerização na adsorção dos macroagentes na MMT e na estabilidade coloidal dos complexos macroagente RAFT / MMT formados. Posteriormente foram avaliados os efeitos do pH, das concentrações dos macroagente RAFT e de MMT, bem como do tipo de iniciador na cinética de polimerização em emulsão \"ab-initio\" de estireno, conduzidas na ausência de surfatantes. As técnicas utilizadas nos estudos de adsorção e para a caracterização das argilas, dos látices híbridos e dos materiais nanocompósitos incluem: espectroscopia de UV-vis, espalhamento dinâmico de luz (DLS), espalhamento eletroforético de luz (ELS), cromatografia de permeação em gel (GPC), análise termogravimétrica (TGA), calorimetria diferencial de varredura (DSC) e microscopia eletrônica de transmissão (TEM). / In recent years, the incorporation of inorganic particles in a polymer matrix in order to obtain hybrid organic/inorganic systems using different polymerization techniques have received great attention. In this sense, preserve and manage the physical and chemical properties of inorganic particles is essential to maintain its integrity at the nanoscale, as well as to obtain uniform dispersions of them, magnifying the effects of reinforcement and other desired properties into the polymer matrix. When using anisotropic inorganic nanoobjects such as montmorillonite, the most used layered silicate to obtain polymer / layered silicate nanocomposites, this control is presented as a particularly challenging problem. In this context, the controlled radical polymerization (CRP) has been highlighted as an important way to achieve the goals mentioned above, several strategies of organic solvent-borne synthesis can be found in literature in which the effective nanoencapsulation of inorganic particles is given by through the growth of polymer chains on the surface of these inorganic structures. However, few works are found involving obtaining similar route in water-borne, such as suspension, emulsion, miniemulsion, these procedures have great interest in industrial, environmental and actual feasibility of expanding scale in manufacture. Thus, the objective of this research project focuses on the synthesis and characterization of nanocomposite-type polymer / layered silicate via controlled radical polymerization in emulsion media. The controlled radical polymerizations in emulsion, via transfer mechanism for the reversible addition-fragmentation chain (RAFT) have been conducted in the presence of montmorillonite clay (MMT) and mediated by two macroRAFT agents with functional tri-thioesters groups, being the first one constituted by a nonionic poly(ethylene glycol) methyl ether polymeric chain (MPEG-CPP) and the second on being MPEG-CPP derived but containing additionally an ionizable block of poly(methacrylic acid) inserted to its polymeric chain. The parameters of adsorption of MPEG-CPP and MPEG-b-PMAA-CPP agent on the surface of MMT as well as the influence of the polymerization process variables on the adsorption of PEO-RAFT in MMT and colloidal stability of the complex formed macroRAFT agents / MMT were firstly evaluated. Subsequently, the influence of pH, macroRAFT agents and MMT concentrations as well as the type of initiator on the kinetics of RAFT emulsion polymerization were equally evaluated. The techniques used the for adsorption studies and characterization of clays, latexes of hybrid materials and nanocomposites include: UV-vis spectroscopy, dynamic light scattering (DLS), electrophoretic light scattering (ELS), gel permeation chromatography (GPC), thermogravimetric analysis (TGA), dynamic scanning calorimetry (DSC) and transmission electron microscopy (TEM).
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Hidr?xidos duplos lamelares aplicados ? obten??o de biodieselAlves, Aline Ara?jo 14 August 2009 (has links)
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Previous issue date: 2009-08-14 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In this paper, the Layered Double Hydroxides (LDH s) type hydrotalcite were synthesized, characterized and tested as basic heterogeneous catalysts for the production of
biodiesel by transesterification of sunflower oil with methanol. The synthesis of materials Layered Double Hydroxides (LDH s) by co-precipitation method from nitrates of magnesium
and aluminum, and sodium carbonate. The materials were submitted to the variation in chemical composition, which is the amount of Mg2+ ions replaced by Al3+. This variation
affects the characteristic physico-chemical and reaction the solid. The molar ratio varied in the range of 1:1 and 3:1 magnesium / aluminum, and their values between 0.2 and 0.33. This study aims to evaluate the influence of variation of molar ratio of mixed oxides derived from LDH s and the influence of impregnation of a material with catalytic activity, the KI, the rate of conversion of sunflower oil into methyl esters (biodiesel) through transesterification by
heterogeneous catalysis. .The catalysts were calcined at 550 ? C and characterized by X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectroscopy of X-ray (SEM / EDS), thermogravimetric analysis (TG) and test basicity. The transesterification reaction was performed for reflux is a mixture of sunflower oil and methanol with a molar
ratio of 15:1, a reaction time of 4h and a catalyst concentration of 2% by weight. The physical-chemical characterization of sunflower oil and biodiesel obtained by the route methyl submitted according NBR, EN, ASTM. Subsequently, it was with the chromatographic and thermogravimetric characterizations of oils. The results of
chromatographic analysis showed that the catalysts were effective in converting vegetable oil into biodiesel, in particular the type hydrotalcite KI-HDL-R1, with a conversion of 99.2%, indicating the strong influence of the chemical composition of the material, in special due to presence of potassium in the structure of the catalyst / Neste trabalho, hidr?xidos duplos lamelares tipo hidrotalcita foram sintetizados, caracterizados e testados como catalisadores heterog?neos b?sicos para a produ??o de
biodiesel por transesterifica??o de ?leo de girassol com metanol. A s?ntese dos materiais de hidr?xidos duplos lamelares (HDLs) procedeu-se pelo m?todo de co-precipita??o, a partir de nitratos de magn?sio e de alum?nio, carbonato de s?dio e hidr?xido de s?dio. Os materiais
foram submetidos ? varia??o na propor??o qu?mica, que equivale ? quantidade de ?ons Mg2+ substitu?dos por Al3+. Essa varia??o afeta as propriedades f?sico-qu?micas do material. A raz?o molar variou na propor??o de 1:1 e 3:1 de magn?sio/alum?nio, estando seus valores entre 0,2 e 0,33. Realizou-se um estudo de impregna??o de iodeto de pot?ssio na estrutura dos HDLs, a fim de verificar se ocorre um aumento da basicidade nesses materiais. Os catalisadores obtidos foram calcinados ? 550 ?C e caracterizados por difra??o de raios X (DRX), microscopia eletr?nica de varredura e espectroscopia por energia dispersiva de raios X (MEV/EDS), an?lise termogravim?trica (TG) e teste de basicidade. A rea??o de transesterifica??o foi realizada refluxando-se uma mistura de metanol e ?leo de girassol com uma raz?o molar de 15:1, tempo de rea??o de 4h e uma concentra??o de 2% em massa de catalisador. A caracteriza??o f?sico-qu?mica do ?leo de girassol e dos biodieseis obtidos atrav?s da rota met?lica apresentou-se de acordo com as normas da NBR, EN, ASTM.
Realizaram-se tamb?m as caracteriza??es cromatogr?ficas e termogravim?tricas dos biocombust?veis obtidos. Os resultados das an?lises cromatogr?ficas mostraram que os
catalisadores foram eficientes na convers?o de ?leo vegetal em biodiesel, em especial o tipo hidrotalcita KI-HDL-R1, com uma convers?o de 99,2%, indicando a forte influ?ncia da
composi??o qu?mica do material, particularmente com a presen?a do iodeto de pot?ssio na estrutura do catalisador
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Evolutions moléculaires au cours de la dégradation biotique et abiotique de polymères bio-sourcés (PLA et PBS) et fossiles à l’aide de la viscoélasticité à l’état fondu / Molecular evolutions during biotic and abiotic degradation of bio-based polymers (PLA and PBS) and fossil polymers thanks to melt viscoelasticityRamoné, Audrey 11 December 2015 (has links)
Pour limiter la production de déchets, la voie de polymères biodégradables est largement explorée. La biodégradation en compost est un phénomène complexe qui dépend de la température, de l’humidité, du soleil et du polymère lui-même. Dans un premier temps, les effets de ces différents paramètres sur la biodégradation de l’acide polylactique (PLA) sont étudiés à l’aide de la viscoélasticité à l’état fondu. Il en résulte que l’échantillon lui-même n’a que peu d’influence sur sa dégradation, mais les conditions de dégradation influencent d’avantage les phénomènes mis en jeu. Dans un deuxième temps, le PLA est associé au poly(butylène succinate) (PBS), un polymère plus favorable à la biodégradation afin d’améliorer la dégradation du PLA. Après s’être intéressée à la biodégradation de polymères « compostables », cette étude se tourne vers la biodégradation d’un polymère non-biodégradable : le polypropylène (PP). Afin d’initier un processus de bio assimilation, des charges sont ajoutées au PP pour dégrader préalablement le polymère et ainsi favoriser l’action des micro-organismes sur les chaines plus courtes. Les hydroxydes doubles lamellaires induisent bien une dégradation mais ce n’est pas assez pour permettre l’assimilation du polymère. Finalement, ce travail aborde la biodégradation de différents polymères dans le but de comprendre ce phénomène et d’améliorer la biodégradation des polymères étudiés. / Nowadays, to minimize our waste production, many studies are focused on environmentally friendly polymers. Degradation in compost is a complex phenomenon with unclear mechanism depending on temperature, micro-organism population, humidity and polymer it-self. In a first hand, these different parameter effects on poly(lactic acid)(PLA) biodegradation are studied with melt viscoelasticity to assess the molecular evolution of the materials during biodegradation. In a second hand, PLA is mixed with a polymer more biodegradable, poly(butylene succinate), to improve PLA biodegradation. After the biodegradation of a compostable polymer, a non biodegradable polymer is studied: polypropylene(PP). To achieve the initiation of its bio-assimilation, fillers are added to promote its degradation and therefore improve its assimilation by micro-organisms. Layered double hydroxides induce degradation but not enough to observe polymer biodegradation.
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Développement de biocapteurs ampérométriques pour la détermination de l’activité de la transcétolase et pour la détection d’inhibiteurs de cette enzyme / Development of amperometric biosensors for the determination of the activity of transketolase and for the detection of inhibitors of this enzymeTouisni, Nadia 13 December 2013 (has links)
Depuis peu, des travaux ont montré que chez l’Homme, la transcétolase (TK, EC 2.2.1.1.) dont le cofacteur est la thiamine diphosphate (forme active de la vitamine B1), est une enzyme impliquée dans de nombreuses maladies telles que, le diabète, certains cancers, ou encore des maladies neurologiques, comme le syndrome de Wernicke-Korsakoff et la maladie d’Alzheimer. Pour des applications thérapeutiques, des inhibiteurs spécifiques de cette enzyme sont actuellement conçus et synthétisés dans les milieux académiques et industriels. Afin de déterminer l’activité de la TK (dans un but de diagnostic) d’une part, et de détecter des inhibiteurs potentiels de cette enzyme (dans un but thérapeutique) d’autre part, il est nécessaire de disposer de tests alliant rapidité, sensibilité et faible coût. Nous avons envisagé d’utiliser des biocapteurs ampérométriques qui combinent l’ensemble de ces avantages, et qui, de plus, n’ont jamais été mis en oeuvre avec la TK. Pour la détermination de l’activité des TK d’E. coli et humaine libres en solution, nous avons tout d’abord élaboré un premier biocapteur à galactose oxydase (GAOx, EC 1.1.3.9), dans lequel cette enzyme est immobilisée sur la laponite. Puis, dans le but de detecter des inhibiteurs de la TK, avec un système réutilisable, nous avons developpé un biocapteur à GAOx-TK d’E. coli, les deux enzymes étant co-immobilisées à la surface de l’électrode. Pour cela la TK a été immobilisée dans des Hydroxydes Doubles Lamellaires (HDL). Ce biocapteur bicouche et bi-enzymatique GAOx-TK, nous a permis d’évaluer l’effet d’inhibiteurs, tels que différents analogues du cofacteur et de substrats pris comme modèles. / Some recent studies have shown that human transketolase (TK, EC 2.2.1.1.), which thiamine diphosphate (active form of vitamin B1) is the cofactor, is involved in numerous disease such as diabete, some cancers and neurodegenerative diseases as Alzheimer’s disease and Wernicke-Korsakoff syndrome. For therapeutic purposes, TK inhibitors have been designed and synthesized in both academic and industrial fields. To determine TK activity (diagnostic) on the one hand, and to detect potential inhibitors of this enzyme (therapeutic) on the other hand, it is necessary to develop fast, sensitive and low cost assays. In this context, we designed some original amperometric biosensors that combine these advantages and were never studied with TK from now. We performed a first galactose oxidase (GAOx, EC 1.1.3.9) biosensor for E. coli and human TK activities detection. For that purpose, GAOx was immobilized on laponite matrix. Then, we designed a GAOx-TK biosensor by co-immobilization of GAOX and TK on the electrode surface that enabled the detection TK inhibitors with a reusable system. Thence, TK was immobilized in Layered Double Hydroxides (HDL). This bilayer and bi-enzymic biosensors, allowed us to determine the inhibitor potencies of several cofactors and substrates analogues as model compounds.
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Electrochemical Advanced Oxidation Processes for removal of Pharmaceuticals from water : Performance studies for sub-stoichiometric titanium oxide anode and hierarchical layered double hydroxide modified carbon felt cathode / Procédés électrochimiques d'oxydation avancée pour l'élimination des composés pharmaceutiques de l'eau : Etude des performances d'une anode d'oxyde de titane sous-stoechiométrique et feutre de carbone modifie par double couche d'hydroxideGaniyu, Soliu 02 December 2016 (has links)
AbstractLes polluants émergents que sont les résidus de produits pharmaceutiques sont devenus une problématique majeure de par leur persistance et leur accumulation continue dans les différents compartiments de l’environnement. Leur élimination est un des challenges majeurs de ce siècle. Les procédés électrochimiques d’oxydation avancée (PEOA) tel que l’oxydation anodique (AO) et l’électro-Fenton (EF) ont démontré leur efficacité pour la dégradation et la minéralisation complète de cette classe de polluant. Un oxyde de titane sous-stœchiométrique déposé par plasma sur un alliage de titane a été étudié comme anode alternative peu coûteuse, stable et efficace au cours des procédés d’OA et d’EF pour la dégradation et la minéralisation de deux pharmaceutiques, l’amoxicilline (AMX) et le propanolol (PPN). Une excellente minéralisation de ces deux composés a été atteinte avec l’anode Ti4O7 comparé à l’utilisation d’une anode dimensionnellement stable (ADS) et d’une anode de platine (Pt) avec des conditions expérimentales similaires, mais une plus faible efficacité a été observé par comparaison à une anode de diamant dopé au bore (DDB) au cours du procédé d’OA. Une quasi-total minéralisation (96%) du PPN a été atteinte avec l’anode Ti4O7 au cours du procédé EF après 8 h d’électrolyse à 120 mA. Plusieurs intermédiaires aromatiques, bicycliques et autres ont été identifiés et quantifiés au cours du traitement électrochimique des deux composés pharmaceutiques, ainsi que des acides carboxyliques à chaîne courte et des ions inorganique comme produits finaux de dégradation. Des voies plausibles de dégradation ont été proposées à partir des intermédiaires identifiés, des ions inorganiques libérés ainsi que des données obtenues sur les acides carboxyliques et le COT. La solution initiale d’AMX a mené à une relativement forte inhibition de la bactérie V. fisheri, qui a ensuite augmenté au cours des premiers stades de l’électro-oxydation de par la formation d’intermédiaires cycliques plus toxiques que la molécule mère, avant de diminuer nettement au cours des étapes suivantes de l’électrolyse. Puisque le Ti4O7 est produit principalement à partir du TiO2, un matériau bon marché et abondant, ce matériau d’anode pourrait être une alternative intéressante pour le traitement des eaux usées industrielles par oxydation électrochimique. Par ailleurs, une cathode de feutre de carbone modifiée par des composés hydroxydes à double couche CoFe (CoFe-LDH/CF) et synthétisée par un procédé solvothermique a été étudiée come catalyseur/électrode pour la dégradation du polluant organique Acide Orange II (AO7) par le procédé EF sur une gamme large de pH. Une excellente minéralisation de ce colorant a été atteinte pour des pH allant de 2 à 7.1, avec une élimination du COT largement supérieure à celle atteinte en utilisant le procédé EF avec une cathode de feutre de carbone brut, quel que soit le pH étudié. La cathode préparée a montré une bonne capacité de réutilisation et peut constituer une alternative pour le traitement des eaux usées à des valeurs de pH naturel / Pharmaceuticals residues as emerging pollutants have become a major concern due to their persistence and continuous accumulation in various environmental compartments and their removal is one the major challenges of this century. Electrochemical advanced oxidation processes (EAOPs) such as anodic oxidation (AO) and electro-Fenton (EF) have shown to be efficient techniques for complete degradation and mineralization of this class of pollutants. A substoichiometric titanium oxide (Ti4O7) deposited on titanium alloy by plasma elaboration was investigated as an alternative stable and efficient low cost anode materials for application in AO and EF for degradation of pharmaceuticals amoxicillin (AMX) and propranolol (PPN) and mineralization of their aqueous solutions. Excellent mineralization of both pharmaceuticals was achieved with Ti4O7 anode compared to dimensional stable anode (DSA) and platinum (Pt) anodes at similar experimental conditions, but less efficient when compared with boron doped diamond (BDD) anode during AO treatment. Almost complete mineralization (96%) was attained with Ti4O7 anode in EF degradation of PPN at 120 mA after 8 h of electrolysis. Several aromatic, bicyclic and other intermediate byproducts were identified and quantified during the electrochemical treatment of both pharmaceuticals, with the final end products in the treated solutions being short-chain carboxylic acids and inorganic ions. Plausible mineralization pathways for both pharmaceuticals were proposed based on the identified intermediates, released inorganic ions and carboxylic acids as well as TOC data. Initial AMX solution shows relatively high inhibition to V. fischeri bacteria, which further increased at the early stage of electrooxidation due to formation of cyclic intermediates more toxic than mother molecules but sharply decreased at the later stage of electrolysis. Since the Ti4O7 is produced mainly from TiO2 which is very cheap and highly abundant material, this anode material could be an interesting alternative electrode in industrial wastewater treatment by electrochemical oxidation. On the other hand, CoFe-layer double hydroxide modified carbon-felt (CoFe-LDH/CF) cathode synthesized by solvothermal process was studied as a heterogeneous catalyst/electrode for degradation of organic pollutant Acid Orange II (AO7) over a wide pH range. Excellent mineralization of this azo dye solution was achieved in pH range 2 – 7.1, with TOC removal much higher than corresponding homogeneous EF with raw carbon-felt (CF) at all pH studied. The prepared cathode exhibited good reusability and can constitute an alternative for the treatment wastewater effluents at neutral pH values
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Preparação e caracterização de hidróxidos duplos lamelares intercalados com espécies macrocíclicas metaladas / Preparation and characterization of layered double hydroxides intercalated with metallated macrocyclic speciesCésar Augusto Sales Barbosa 08 July 1999 (has links)
O presente trabalho tem como objetivo a síntese e caracterização de hidróxido duplo lamelar (HDL) do tipo hidrotalcita intercalado com metaloftalocianinas (CuPcTs e CoPcTs) e metaloporfirina (CoTPhsP) aniônicas. Como rota sintética, três métodos foram testados: (i) coprecipitação do hidróxido duplo em solução contendo o macrociclo; (ií) reconstituição estrutural da mistura de óxidos obtida pela decomposição térmica de HDL na forma carbonato e (ííi) decomposição térmica do carbonato intercalado empregando um meio contendo poliol. A influência do método de intercalação nas propriedades texturais do material e o efeito da imobilização dos macrociclos na região interlamelar foram avaliados através da caracterização textural (difração de raios-X e medidas de área superficial), espectroscópica (vibracional no infravermelho, eletrônica no UV/visível e ressonância paramagnética eletrônica) e das análises elementar (C, H, N e metais) e termogravimétrica. Avaliou-se a influência das propriedades texturais dos compósitos e do arranjo dos intercalados na reatividade e estabilidade dos macrociclos confinados no espaço interlamelar através da reação de decomposição do peróxido de hidrogênio. A síntese por coprecipitação dos hidróxidos duplos lamelares do tipo hidrotalcita mostrou-se eficiente para a obtenção de produtos puros e de alta cristal inidade. Entretanto, os materiais obtidos a partir da intercalação dos macrociclos nas matrizes de HDL através dos diferentes métodos sintéticos resultaram em sólidos com baixa cristalinidade. Os estudos mostraram que a obtenção de materiais contendo apenas uma fase é dependente do método de intercalação empregado. Os resultados de análise elementar indicaram um alto grau de intercalação dos macrociclos nos HDLs. Os espectros vibracionais no infravermelho apresentaram bandas que podem ser atribuídas à presença de íons carbonato no espaço interlamelar dos sistemas HDL-macrociclos. A incorporação completa do macrociclo foi observada para a CoPcTs intercalada no HDL via método da coprecipitação. Por outro lado, o método do poliol, utilizado para a intercalação da CuPcTs e CoPcTs, resultou em materiais com baixo grau de intercalação. A intercalação dos macrociclos nos HDLs foi confirmada através dos resultados obtidos por difração de raios-X, que indicaram um aumento substancial do espaçamento basal, que aumentou de aproximadamente 8A nas matrizes precursoras contendo CO32- para cerca de 23A nas matrizes contendo os macrociclos intercalados. As medidas de área superficial sugerem que não houve a formação de microporos nos HDLs incorporados com os macrociclos, pois estes não apresentaram valores de área superficial significativamente maior que os das matrizes de HDL na forma carbonato. A intercalação da CoPcTs e da CoTPhsP aumenta tanto a estabilidade térmica dos HDLs em relação à matriz com carbonato, quanto a dos próprios macrociclos. Em relação aos HDLs contendo a CuPcTs, observou-se comportamento térmico distinto. A intercalação da CuPcTs também aumenta a estabilidade térmica do HDL mas o confinamento do macrociclo provoca a sua decomposição em temperatura menor que aquela observada quando livre. Os espectros de absorção eletrônica mostraram que as metaloftalocianinas quando intercaladas nos HDLs apresentaram menor grau de agregação às espécies livres. Porém, os espectros de RPE indicaram que as espécies CuPcTs agregados são dominantes nas amostras intercaladas uma vez que apresentam apenas valor de g isotrópico (g=2,06). Os sistemas com a CoPcTs também apresentaram agregados mas em menor extensão que aqueles com os análogos de Cu(II). Com relação ao comportamento catalítico dos diferentes materiais sintetizados na decomposição do peróxido de hidrogênio, os três macrociclos estudados apresentaram comportamentos distintos. A CuPcTs suportada e intercalada no HDL não apresenta atividade catalásica embora a forma livre promova a dismutação do H2O2. Os materiais com a CoPcTs e CoTPhsP são mais ativos que o macrociclo livre na decomposição do peróxido de hidrogênio. Os HDLs com a CoTPhsP são mais resistentes ao ataque oxidativo do peróxido de hidrogênio que a porfirina livre. As ftalocianinas metaladas em meio homogêneo ou heterogêneo não são degradadas pelo H202. Preparation and characterization of layered double hydroxides intercalated with macrocyclic metallated species / The aim of the present work is to synthesize and characterize layered double hydroxides (hydrotalcite-like compounds) intercalated with anionic metallophthalocyanines (CuPcTs and CoPcTs) and metalloporphyrin (CoTPhsP). Three preparative methods were tested to isolate the intercalated materiais: (i) double hydroxide coprecipitation in the presence of the macrocycle, (ii) structure reconstruction of the mixed oxides obtained by thermal decomposition of layered double hydroxide (LDH) phase containing volatile ion; (iii) thermal decomposition of carbonate-containing phase in a polyol media. The influence of the intercalation method in the material textural properties and the effect of the macrocycle immobilization in the interlayer region were evaluate through the textural characterization (x-ray diffraction analysis and surface area measurements), vibrational (IR) and electronic (UV-visible) spectroscopy, elementary analysis and thermogravimetry. The effect of the composites textural properties and the intercalated species arrangement in the LDH gallery was evaluate carrying out the hydrogen peroxide decomposition reaction. The LDHs preparation by coprecipitation was an efficient method to obtain pure and crystalline products. However the macrocycle intercalated materiais isolated by the three methods mentioned above were poorly crystallized phases. The experimental data also showed that the isolation of materiais containing only one phase depends on the synthetic approach. The extension of intercalated macrocycle species in LDHs was broad as judged by elementary analysis data. The IR vibrational spectra showed some bands that can be attributed to the presence of carbonate ions in the interlayer of LDH macrocycle systems. Material containing approximately 100% of macrocycle in the LDH gallery was isolated by the double hydroxide coprecipitation in a solution containing CoPcTs. On the other hand, polyol method rendered materiais with small amount of intercalated metallophthalocyanines. The macrocycle intercalation between LDHs layers was confirmed by the x-ray diffraction patterns: the basal spacing of the carbonate precursor (ca. 8A) increases to approximately 23A in the matrices intercalated with phthalocyanines or porphyrin. The surface area data suggested that the macrocycle intercalated solids do not have microporous owing to the fact that as the surface area values are not higher than that obtained for the LDH precursor. CoPcTs and CoTPhsP intercalation increases the thermal stability of HDLs in relation to the carbonate phase as much as the macrocycle stability. CuPcTs systems showed a particular behaviour: the thermal stability of LDH structure is increased but the phthalocyanine decomposition occurs in a lower temperature than that observed to the macrocycle free form. The electronic absorption spectra revealed a decrease in the metallophthalocyanine aggregation when the species are intercalated in LDHs However the EPR spectra showed only the isotropic g value (g=2.07) evidencing that the CuPcTs aggregated species are dominant in the LDH samples. CoPcTs systems are also aggregated but in a less extension than the Cu(lI) compound. The catalase-like activity of the intercalated materiais was distinct for each macrocycle system tested. CuPcTs intercalated or supported in LDHs is not active in the hydrogen peroxide dismutation in despite of the free form shows activity. CoPcTs and CoTPhsP materiais exhibit better catalytic performance than the free macrocycles. LDHs containing CoTPsP are more resistant to the oxidative attack of hydrogen peroxide than the free porphyrin. Metallophthalocyanines species in homogeneous or heterogeneous media are not degraded by H202.
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