The thesis discusses how to utilize Sol-gel method to prepare nano-sized TiO2 films of photoelectrodes and the their use in Dye-Sensitized Solar Cells. The main goal is the study on the production of TiO2 photoelectrodes. When making nano-sized TiO2 films of photoelectrodes, we have to first produce TiO2 sol via the Sol-gel method optical thin films are then made by spin coating. After its spin coating, we study the crystalline phase and morphology of nano-sized TiO2 films of photoelectrodes in terms of two ways: Supercritical drying and oven drying. Among the Dye-Sensitized Solar Cells that are made with different drying methods, owing to higher porosity and surface area, the nano-sized TiO2 films of photoelectrodes made by supercritical drying adsorb more dye molecules and are thus more efficient.

The pyroelectric ceramic thin films and detectors based on PbTiO3 that exhibits a low dielectric constant and a high pyroelectric coefficient were fabricated by a sol-gel method in this thesis. The lanthanum (La) and calcium (Ca) were adopted as dopants. The PLT and PCT thin films were deposited on Pt/SiO2/Si substrates by spin coating. 1,3 propanediol was used as solvent to minimize the number of cycles of spin coating and drying processes to obtain the desired thickness of thin film. By changing the dopant content and the heating temperature, the effects of various processing parameters on the thin films growth are studied. The effects of various dopant contents on the response of pyroelectric detectors are also discussed. Experimental results reveal that the dopant contents will influence strongly on the characteristics of thin films such as microstructure, dielectricity, ferroelectricity and pyroelectricity. With the increase of dopant content, the grain size, the coercive field (Ec) and the remanent polarization (Pr) of thin films decrease. The relative dielectric constant (£`r) and the pyroelectric coefficient (g) of thin films increase with increasing the dopant content. In addition, the results also show that the PLT(10) and the PCT(25) thin films exhibit large figures of merit Fv for voltage responsivity (Rv) and Fm for specific detectivity (D*) at the heating temperature of 700¢J. In the pyroelectric properties of thin film detectors, Rv and D* increased with an increase of dopant content. However, Rv and D* decreased when La and Ca content exceeded 10 mol% and 25 mol%, respectively. The PLT(10) and the PCT(25) pyroelectric thin film detectors exist both the maximums of Rv and D*. The results are consistent with the evaluations of Fv and Fm of thin films.

Este trabalho descreve o desenvolvimento e caracterização de novos materiais catalíticos para a oxidação de metanol em aplicações em células a combustível de metanol direto. Os materiais foram preparados utilizando o método sol-gel pela incorporação de diversas quantidades de metais, tais como: Ru, Ir, Ce, Mo e Pb sobre amostras de pó de Pt/C da E-Tek (10% Pt). Na maioria dos casos, o compósito resultante estava formado pelos referidos óxidos metálicos como observado nas medidas de caracterização física. Os sistemas estudados incluíram as seguintes misturas binárias: (Pt0,50-(RuO2)0,50/C, Pt0,50-(IrOx)0,50/C, Pt0,50-(CeO,sub>2)0,50/C, (PtOx)0,50-(PbOx)0,50/C, Pt0,50-(Môo3)0,50/C) e as misturas ternárias: (Pt0,25(RuO2-IrOx)0,75/C, Pt0,50 (RuO2-IrOx)0,50/C, Pt0,75(RuO2-IrOx)0,25/C, Pt0,25(RuO2-CeO2)0,75/C, Pt0,50 (RuO2-CeO2)0,50/C, Pt0,75(RuO2-CeO2)0,25/C, (PtOx)0,25(RuO2- PbOx)0,75/C, (PtOx)0,50 (RuO2-PbOx)0,50/C, (PtOx)0,75(RuO2-PbOx)0,25/C, Pt0,25(RuO2- Môo3)0,75/C, Pt0,50(RuO2-MoO3)0,50/C e Pt0,75(RuO2-MoO3)0,25/C). Medidas de difratometria de raios-X, mostraram que todos os metais incorporados às amostras de Pt/C sintetizam-se como óxidos (RuO2, IrO2, Ir2O3, CeO2, Pb3O4 e MoO3), enquanto que a platina manteve-se como Pt metálica com exceção nos compósitos contendo chumbo, nos quais na sua composição final mostraram Pt, assim como, PtO e PtO2. Os compósitos preparados pelo método sol-gel foram de tamanho nanométrico (2,8- 3,5 nm) como observado por microscopia eletrônica de transmissão assim como por difração de raios-X, enquanto que, medidas de energia dispersiva de raios-X mostraram que os compostos apresentam composições próximas aos valores usados na preparação experimental. A oxidação de metanol foi estudada em todos os compósitos por voltametria cíclica seguida pelas curvas de polarização em estado quase-estacionário com os correspondentes diagramas de Tafel e finalmente pelos testes cronoamperométricos com análise por cromatografia dos principais produtos na solução. x Os valores do coeficiente angular obtidos nos diagramas de Tafel (b) são um indicativo que a etapa determinante da velocidade da reação (rds) de eletro-oxidação de metanol sobre os catalisadores contendo Ir é a quebra de uma das ligações C-H na molécula de CH3OH com a transferência do primeiro elétron (b = 120 mV dec-1). Entretanto, para os outros catalisadores estudados os valores de (b estão em torno de 90 mV dec-1, indicando que a rds nesses casos pode ser à remoção oxidativa do COads pelos intermediários adsorvidos provenientes da oxidação da molécula de água (R-OH.). Por outro lado, análises cromatográficos dos produtos formados em solução durante os testes cronoamperométricos mostraram que o compósito Pt0,25(RuO2-IrOx)0,75/C apresentou o melhor desempenho catalítico para oxidação de metanol. Isto devido a que, sobre este catalisador, não foi observado acúmulo de formaldeído em quanto que o ácido fórmico remanescente foi menor do que o observado sobre os outros catalisadores estudados, usando cargas elétricas equivalentes. Isto é um forte indicativo de que a oxidação de metanol em este material é eficiente, oxidando também moléculas de formaldeído e ácido fórmico até CO2 sem a formação de intermediários solúveis na solução. Portanto, este estudo mostra claramente que os melhores catalisadores para a oxidação de metanol são: Pt0,25(RuO2-IrOx)0,75/C, Pt0,50(RuO2-IrOx)0,50/C e Pt0,75(RuO2-IrOx)0,25/C, confirmando que a combinação de Pt, Ru e Ir é promissora para esta aplicação. / The preparation and the physical and electrochemical characterization of several binary and tertnary new composite catalytic materials for the direct oxidation of methanol in fuel cell systems are described here. The materials were prepared using the sol-gel method for the incorporation of variable amounts of metals such as Ru, Ir, Ce, Mo and Pb onto commercial samples of Pt/C powder from E-Tek (10% Pt). In most cases, the resulting composite was formed by the corresponding metal oxides as indicated by the subsequent physical characterization measurements. The systems studied included the following binary mixtures: Pt0,50-(RuO2)0,50/C, Pt0,50-(IrOx)0,50/C, Pt0,50-(CeO,sub>2)0,50/C, (PtOx)0,50-(PbOx)0,50/C, Pt0,50-(Môo3)0,50/C and the ternary ones: Pt0,25(RuO2-IrOx)0,75/C, Pt0,50 (RuO2-IrOx)0,50/C, Pt0,75(RuO2-IrOx)0,25/C, Pt0,25(RuO2-CeO2)0,75/C, Pt0,50 (RuO2-CeO2)0,50/C, Pt0,75(RuO2-CeO2)0,25/C, (PtOx)0,25(RuO2- PbOx)0,75/C, (PtOx)0,50 (RuO2-PbOx)0,50/C, (PtOx)0,75(RuO2-PbOx)0,25/C, Pt0,25(RuO2- Môo3)0,75/C, Pt0,50(RuO2-MoO3)0,50/C and Pt0,75(RuO2-MoO3)0,25/C X-ray diffraction measurements revealed that all metals incorporated to the Pt/C samples appeared as oxides (e.g. RuO2, IrO2, Ir2O3, CeO2, Pb3O4 e MoO3) while platinum remained metallic except for the composites containing lead where the final composition showed metallic Pt as well as PtO and PtO2. The sol-gel prepared composites were nanometric in size (2.8 - 3.5 nm) as shown by electronic transmission microscopy as well as by X-ray diffraction while energy dispersive Xray measurements indicated that the composites have compositions values very close to those of the experimental preparation. Methanol oxidation was studied on all composites by cyclic voltammetry followed by quasi steady-state polarization curves with the corresponding Tafel plots and, finally, by chronoamperometric tests with analyses of the main products in solution by chromatography. xii The measured values of the Tafel coefficient (b) are an indicative that the ratedetermining- step (rds) for methanol oxidation on catalysts containing Ir is the rupture of one of the C-H bonds in the CH3OH molecule with the transference of one electron (CH3OH = ~120 mV dec-1). For the other composites studied the b values are around 90 mV dec-1 indicating that the rds in those cases could be the oxidative removal of COads by the adsorbed intermediates of the water molecule oxidation (R-OH.). On the other hand, the chromatographic analyses of the products formed in solution during the chronoamperometric tests seem to point out that the Pt0,25(RuO2-IrOx)0,75/C composite is the one with the best catalytic performance for methanol oxidation. This is because for that material an accumulation of formaldehyde was not observed while the remnant formic acid was lower than for the other tested composites using equivalent electric charges. This is a strong indicative that the oxidation of methanol on that material efficiently also oxidizes the formaldehyde and the formic acid molecules to CO2 not leaving soluble intermediates in solution. Therefore, the present studies clearly show that the best catalysts for methanol oxidation are: Pt0,25(RuO2-IrOx)0,75/C, Pt0,50(RuO2-IrOx)0,50/C e Pt0,75(RuO2-IrOx)0,25/C, thus confirming that a proper combination of Pt, Ru and Ir is very promising for such application.

The lithium tantalite [LiTaO3, abbreviated to LT] thin films were deposited on Pt/Ti/SiO2/Si substrates by spin coating with sol-gel technology and various rapid thermal processing in this thesis. By changing the annealed layers and heating temperature(500~800¢J), the effects of various thermal treatments on the thin films growth and the related properties are studied. Besides, the dynamic response of pyroelectric IR detector using LiTaO3 films was studied. In addition, the detector with back side etching was achieved by the anisotropic wet etching of back silicon substrate. The comparisons of detectors with and without backside etching were also investigated. Experimental results reveal that the annealed layers will influence strongly on grain size, dielectricity, ferroelectricity and pyroelectricity of LT thin films. With the increase of the annealed layers, the grain size of LT thin film increases slightly, and highly c-axis orientated LT films can be obtained for the twelve annealed layers. From 4 to 12 annealed layers, the relative dielectric constant of LT thin film increases from 35 up to 65, the dielectric loss (tand) decreases from 0.00637 to 0.00324, the coercive field (Ec) decreases from 84.79KV/cm to 46.23KV/cm, the remnant polarization (Pr) increases from 2.54 mC/cm2 to 7.36 mC/cm2, and the pyroelctric coefficient (g) increases from 2.18´10-8 C/cm2K up to 5.71´10-8 C/cm2K. In addition, the results also show that the LT thin film possesses the largest figures of merit Fv (3.02¡Ñ10-10 Ccm/J) and Fm (4.08¡Ñ10-8 Ccm/J) at heating temperature of 700¢J with twelve annealed layers. The voltage responsivities (Rv) measured at 70 Hz exists a largest value of 8398 V/W with twelve annealed layers. The specific detectivity (D*) measured at 200 Hz has the maximum value of 1.1¡Ñ108 cmHz1/2/W with twelve annealed layers. The results show that LT12 pyroelectric thin film detector exists both the maximums of voltage responsivity and specific detecivity. Therefore, optimizing the conditions of this study, LT12 thin film will be the most suitable for IR detector application. Finally, the voltage responsivities (Rv) of LT thin film increases from 8398 V/W to 9537 V/W, and the specific detectivity (D*) increases from 1.1¡Ñ108 cmHz1/2/W to 2.67¡Ñ108 cmHz1/2/W after backside etching. The results show that the detectivity can be improved after backside etching.

Metal coordinated polymer nanocomposites have gained great attention due to their superior characteristics. Polymethylmethacyrlate (PMMA) is the most commonly used polymer since it is easily processed. In this study, modified TiO2 nanoparticles prepared by insitu and exsitu methods were embedded into PMMA in order to improve its thermal stability and the effects of TiO2 nanoparticles on thermal characteristics of PMMA were investigated by direct pyrolysis mass spectrometry. The insitu method which is a sol gel method, TiO2/SiO2 nanoparticles were synthesized by mixing titanium(IV) tetraisopropoxide, TTIP, with silane coupling agent, 3-(3-methoxysilyl)methylmetacrylate, MSMA in absolute ethanol. In exsitu method, TiO2 powder was directly mixed with silane coupling reagent. TiO2/SiO2 nanoparticles were embedded into the PMMA by direct mixing resulting in exsitu and insitu TiO2/SiO2/PMMA nanocomposites. The synthesized TiO2/SiO2/PMMA nanocomposites were characterized by TEM, ATR-FT-IR and analyzed for the investigation of their reaction mechanism and thermal characteristics by pyrolysis mass spectroscopy. iv TEM images confirmed the formation of TiO2/SiO2 nanoparticles and TiO2/SiO2/PMMA nanocomposites and indicated that the average particle size of TiO2/SiO2 nanoparticles was around 6 nm whereas average particle size of SiO2/TiO2/PMMA nanocomposites were around 25 nm. The increase in the size of nanoparticles is associated with incorporation of TiO2/SiO2 nanoparticles into PMMA matrix. ATR-FTIR spectrum of 5% TiO2/SiO2/PMMA nanocomposites showed the formation of TiO2/SiO2 nanopartciles clearly. Pyrolysis mass spectrometry analysis revealed that incorporation of TiO2/SiO2 nano- particles into PMMA resulted in higher thermal stability only for low weight percentage insitu TiO2/SiO2/PMMA. At high weight percentages a decrease in thermal stability was detected. On the other hand, in case of exsitu TiO2/SiO2/PMMA, contrary to our expectations a decrease in thermal stability was detected. The decrease in thermal stability was attributed to evolution of methacrylic acid during thermal degradation of silane groups.

The Ta-modified niobate lithium [LiNb1-xTaxO3, abbreviated to LNT] thin films were deposited on Pt/Ti/SiO2/Si substrates by spin coating with sol-gel technology and rapid thermal processing in this thesis. 1,3 propanediol was used as solvent to minimize the number of cycles of spin coating and drying processes to obtain the desired thickness of thin film. By changing the Ta content (x=0~1), the effects of various processing parameters on the thin films growth are studied. The effects of various Ta content on the response of pyroelectric IR detector devices are studied also. Experimental results reveal that the Ta content will influence strongly on grain size, dielectricity, ferroelectricity and pyroelectricity of LNT thin films. With the increase of Ta content, the grain size of LNT thin film decreases slightly, and highly c-axis orientated LNT films have been obtained for x=0.2. With the increase of Ta content, The relative dielectric constant of LNT thin film increases from 33 up to 62. The dielectric loss (tand) increases from 0.00374 to 0.00686,Coercive Field (Ec) decreases from 81.09KV/cm to 32.07KV/cm, and Remanent polarization (Pr) decreases from 8.48 mC/cm2 to 2.2 mC/cm2, pyroelctric coefficient (g) increases from 2.76´10-8 C/cm2K up to 4.51´10-8 C/cm2K with an increase of Ta content. In addition, the results also show that the LNT thin film possesses the largest figures of merit Fv (2.66¡Ñ10-10 Ccm/J) and Fm (2.57¡Ñ10-8 Ccm/J) at the heating temperature of 700¢J and Ta content of 20mol%. The voltage responsivities (Rv) measured at 70 Hz has a largest value of 7020 V/W with the Ta content of 20mol%. The specific detectivity (D*) measured at 200 Hz has the maximum value of 7.76¡Ñ107 cmHz1/2/W with the Ta content of 20mol%. The results show that LNT(20) pyroelectric thin film detector exists both the maximums of voltage responsivity and specific detecivity. Therefore, optimizing the conditions of this study, LNT(20) thin film will be the most suitable for IR detector application.

Orientador: Gustavo Rocha de Castro / Banca: Cláudio Luiz Carvalho / Banca: Ademir dos Santos / Resumo: Nas ultimas décadas, muitos dos trabalhos científicos estão relacionados à qualidade das águas naturais, como por exemplo, na identificação e quantificação de contaminantes orgânicos e inorgânicos. Dentre as espécies inorgânicas os metais potencialmente tóxicos são os mais estudados e, devido à baixa concentração em que algumas espécies são encontradas no ambiente, torna-se necessário a utilização de equipamentos sofisticados para sua quantificação segura. O uso de materiais como sílicas organofuncionalizadas para aplicação em extração em fase sólida (SPE) possibilita a pré-concentração desses íons e garante uma quantificação com maior segurança mesmo em equipamentos mais simples como espectrômetros de absorção atômica com atomização por chama. Neste contexto, o presente trabalho consistiu na síntese da sílica pelo método sol-gel, sua organofuncionalização com o ligante 4-amino-2-mercaptopirimidina (AMP), caracterização e aplicação do material na extração de íons Cu(II), Cd(II) e Pb(II) em meio aquoso. Os espectros de FTIR evidenciaram o ancoramento do ligante na sílica com a identificação de bandas em 1582 e 1541 cm-1 referente aos grupos NH e 3347 cm-1 referente aos grupos NH2 presentes na molécula do ligante. O ancoramento do ligante resultou no decréscimo das medidas de área superficial de 737 m2 g-1 para 399 m2.g-1, o qual esta relacionado a obstrução dos poros pelo ancoramento das moléculas orgânicas. Os espectros de RMN de 13C e 29Si confirmaram a presença ligações covalentemente entre a superfície da sílica e o grupo orgânico. Com os dados da análise elementar estimou-se uma quantidade de 3,619 10-4 mols do ligante por grama de SG-AMP. O sistema de pré-concentração foi otimizado utilizando o método univariado e os valores para a vazão da amostra e do eluente... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In the last decades, many scientific works are related to the quality of natural waters, such as the identification and quantification of organic and inorganic contaminants. Among the inorganic species potentially toxic metals are the most studied and, because of the low concentration of some species are found in the environment, it becomes necessary to use sophisticated equipment to secure its quantification. The use of materials such as silica organofuncionalized for application in solid phase extraction (SPE) allows preconcentration of these ions and provides quantification more safely even in the simplest equipment as atomic absorption spectrometers in flame module. In this context, this work was the synthesis of silica by sol-gel method, its organofuncionalization with the ligand 4-amine-2- mercaptopyrimidine (AMP), characterization and application of the material in the extraction of Cu (II), Cd (II ) and Pb (II) in aqueous means. The material was analyzed by FTIR showed the anchoring of the ligand on the silica by the identification of bands in 1582 and 1541 cm-1 on the NH groups and 3347 cm-1 on the NH2 groups present in the ligand molecule. The anchoring of the ligand resulted in the decrease of the measures of surface area of 737 m2 g-1 for 399 m2.g-1, which is related to clogged pores by anchoring of organic molecules. The NMR spectra of 13C and 29Si confirmed the presence of covalent bonds between the surface of silica and organic group. The data from elemental analysis to estimate an amount of 3.619 x 10-4 moles of ligand per gram of SG-AMP. The system of pre-concentration was optimized using the univariate method and the values for the flow of sample and eluent were set at 1.0 mL min-1, pH 5 to sample and nitric acid 2 mol L-1 as the eluent. The silica produced had a maximum adsorption of 0.0027, 0.0028 and 0.0018 mmol g-1 Cu (II), Cd (II) and Pb (II), respectively. / Mestre

Visando atender às necessidades de consumidores mais exigentes e preocupados com a saúde, este trabalho propôs um estudo de propriedade antimicrobiana de extratos naturais como antocianinas, tanino, urucum, curcumina e extrato de folha de oliveira e antioxidante para antocianinas, todos em sua forma livre e encapsulados numa rede de sílica. Diante das características de mudança de coloração do extrato de antocianinas frente à alteração de pH do meio o uso desse composto no desenvolvimento de filme em matriz polimérica de quitosana/PVA como embalagem ou etiqueta ativa e inteligente. Os extratos foram encapsulados em sílica em diferentes concentrações variando de 2,5% a 50% utilizando rota ácida e rota básica com precursor tetraetoxisilano e caracterizados quanto à preservação da funcionalidade e estrutura molecular, textura e morfologia e estabilidade térmica. Os filmes foram avaliados quanto às propriedades mecânicas, espessura, análises térmicas, caracterização química e análise de mudança de cor com filé de peixe tilápia (Tilápia rendali) cru com aplicação direta sobre a carne, sob refrigeração, correlacionada com mudança de pH do peixe e Contagem Bacteriana Total (CBT). Os resultados obtidos foram promissores, uma vez que dentre os bioativos livres o urucum, tanino e antocianina apresentaram resultados bastante satisfatórios quanto à ação antimicrobiana com zona de inibição no método de difusão entre 10 a 22 mm. Quando encapsulados, os extratos destaque foram a antocianina e o tanino com zona de inibição entre 9 a 21mm. Quanto ao filme indicador avaliado demonstrou ser um bom indicador de pH ao mudar de cor via colorímetro mas a olho nu a mudança não foi percebida nitidamente. A sua resistência à ruptura aumentou em aproximadamente 20 vezes em relação ao filme controle. Entretanto a deformação na ruptura diminuiu em torno de 30% tornando-o mais rígido. / The present work investigated needs of demanding and concerned consumers with their health, this work proposes a study of antimicrobial and/or antioxidant properties of natural extracts as anthocyanins, tannin, anatto, curcumin and olive leaf extracts and antioxidant for anthocyanins, in free state and encapsulated within silica network. Due to of color change features of anthocyanins extract under pH variation, this compound was used in the preparations of quitosan/PVA film as intelligent and active packaging. The extracts were encapsulated in silica in different concentrations from 2,5% to 50% using acid and basic sol-gel catalyzed route route with tetraetoxisilane as precursor and characterized as the funcionality preservation and molecular structure, texture and morfology and thermal estability. The films were evaluated in terms of mechanical properties, thickness, thermal analysis, chemical characterization and fish fillet tilápia (Tilápia rendali) crude color change analysis with direct application on meat, under refrigeration, correlated with fish pH changing and Total Bacterial Counting (CBT). The results were promising since among the free bioactive the anatto, tannin and anthocyanin showed very satisfactory results in terms of antimicrobial action with inhibition zone in the diffusion method between 10 to 22 mm. When encapsulated, the featured extracts were anthocyanin and tannin with inhibition between 9 to 21mm. The measured indicator film demonstrated to be a good pH indicator because color changing through colorimeter but to the naked eye the color changing was not clearly observed. The rupture strength increased about 20 times comparing to the control film. However the elongation at break decreases around 30% turning it hard.

Visando atender às necessidades de consumidores mais exigentes e preocupados com a saúde, este trabalho propôs um estudo de propriedade antimicrobiana de extratos naturais como antocianinas, tanino, urucum, curcumina e extrato de folha de oliveira e antioxidante para antocianinas, todos em sua forma livre e encapsulados numa rede de sílica. Diante das características de mudança de coloração do extrato de antocianinas frente à alteração de pH do meio o uso desse composto no desenvolvimento de filme em matriz polimérica de quitosana/PVA como embalagem ou etiqueta ativa e inteligente. Os extratos foram encapsulados em sílica em diferentes concentrações variando de 2,5% a 50% utilizando rota ácida e rota básica com precursor tetraetoxisilano e caracterizados quanto à preservação da funcionalidade e estrutura molecular, textura e morfologia e estabilidade térmica. Os filmes foram avaliados quanto às propriedades mecânicas, espessura, análises térmicas, caracterização química e análise de mudança de cor com filé de peixe tilápia (Tilápia rendali) cru com aplicação direta sobre a carne, sob refrigeração, correlacionada com mudança de pH do peixe e Contagem Bacteriana Total (CBT). Os resultados obtidos foram promissores, uma vez que dentre os bioativos livres o urucum, tanino e antocianina apresentaram resultados bastante satisfatórios quanto à ação antimicrobiana com zona de inibição no método de difusão entre 10 a 22 mm. Quando encapsulados, os extratos destaque foram a antocianina e o tanino com zona de inibição entre 9 a 21mm. Quanto ao filme indicador avaliado demonstrou ser um bom indicador de pH ao mudar de cor via colorímetro mas a olho nu a mudança não foi percebida nitidamente. A sua resistência à ruptura aumentou em aproximadamente 20 vezes em relação ao filme controle. Entretanto a deformação na ruptura diminuiu em torno de 30% tornando-o mais rígido. / The present work investigated needs of demanding and concerned consumers with their health, this work proposes a study of antimicrobial and/or antioxidant properties of natural extracts as anthocyanins, tannin, anatto, curcumin and olive leaf extracts and antioxidant for anthocyanins, in free state and encapsulated within silica network. Due to of color change features of anthocyanins extract under pH variation, this compound was used in the preparations of quitosan/PVA film as intelligent and active packaging. The extracts were encapsulated in silica in different concentrations from 2,5% to 50% using acid and basic sol-gel catalyzed route route with tetraetoxisilane as precursor and characterized as the funcionality preservation and molecular structure, texture and morfology and thermal estability. The films were evaluated in terms of mechanical properties, thickness, thermal analysis, chemical characterization and fish fillet tilápia (Tilápia rendali) crude color change analysis with direct application on meat, under refrigeration, correlated with fish pH changing and Total Bacterial Counting (CBT). The results were promising since among the free bioactive the anatto, tannin and anthocyanin showed very satisfactory results in terms of antimicrobial action with inhibition zone in the diffusion method between 10 to 22 mm. When encapsulated, the featured extracts were anthocyanin and tannin with inhibition between 9 to 21mm. The measured indicator film demonstrated to be a good pH indicator because color changing through colorimeter but to the naked eye the color changing was not clearly observed. The rupture strength increased about 20 times comparing to the control film. However the elongation at break decreases around 30% turning it hard.

Visando atender às necessidades de consumidores mais exigentes e preocupados com a saúde, este trabalho propôs um estudo de propriedade antimicrobiana de extratos naturais como antocianinas, tanino, urucum, curcumina e extrato de folha de oliveira e antioxidante para antocianinas, todos em sua forma livre e encapsulados numa rede de sílica. Diante das características de mudança de coloração do extrato de antocianinas frente à alteração de pH do meio o uso desse composto no desenvolvimento de filme em matriz polimérica de quitosana/PVA como embalagem ou etiqueta ativa e inteligente. Os extratos foram encapsulados em sílica em diferentes concentrações variando de 2,5% a 50% utilizando rota ácida e rota básica com precursor tetraetoxisilano e caracterizados quanto à preservação da funcionalidade e estrutura molecular, textura e morfologia e estabilidade térmica. Os filmes foram avaliados quanto às propriedades mecânicas, espessura, análises térmicas, caracterização química e análise de mudança de cor com filé de peixe tilápia (Tilápia rendali) cru com aplicação direta sobre a carne, sob refrigeração, correlacionada com mudança de pH do peixe e Contagem Bacteriana Total (CBT). Os resultados obtidos foram promissores, uma vez que dentre os bioativos livres o urucum, tanino e antocianina apresentaram resultados bastante satisfatórios quanto à ação antimicrobiana com zona de inibição no método de difusão entre 10 a 22 mm. Quando encapsulados, os extratos destaque foram a antocianina e o tanino com zona de inibição entre 9 a 21mm. Quanto ao filme indicador avaliado demonstrou ser um bom indicador de pH ao mudar de cor via colorímetro mas a olho nu a mudança não foi percebida nitidamente. A sua resistência à ruptura aumentou em aproximadamente 20 vezes em relação ao filme controle. Entretanto a deformação na ruptura diminuiu em torno de 30% tornando-o mais rígido. / The present work investigated needs of demanding and concerned consumers with their health, this work proposes a study of antimicrobial and/or antioxidant properties of natural extracts as anthocyanins, tannin, anatto, curcumin and olive leaf extracts and antioxidant for anthocyanins, in free state and encapsulated within silica network. Due to of color change features of anthocyanins extract under pH variation, this compound was used in the preparations of quitosan/PVA film as intelligent and active packaging. The extracts were encapsulated in silica in different concentrations from 2,5% to 50% using acid and basic sol-gel catalyzed route route with tetraetoxisilane as precursor and characterized as the funcionality preservation and molecular structure, texture and morfology and thermal estability. The films were evaluated in terms of mechanical properties, thickness, thermal analysis, chemical characterization and fish fillet tilápia (Tilápia rendali) crude color change analysis with direct application on meat, under refrigeration, correlated with fish pH changing and Total Bacterial Counting (CBT). The results were promising since among the free bioactive the anatto, tannin and anthocyanin showed very satisfactory results in terms of antimicrobial action with inhibition zone in the diffusion method between 10 to 22 mm. When encapsulated, the featured extracts were anthocyanin and tannin with inhibition between 9 to 21mm. The measured indicator film demonstrated to be a good pH indicator because color changing through colorimeter but to the naked eye the color changing was not clearly observed. The rupture strength increased about 20 times comparing to the control film. However the elongation at break decreases around 30% turning it hard.