The polymer-clay nanocomposites, when applied as coating materials, are expected to improve the barrier properties without sacrificing mechanical and thermal properties, and thus solve one of the most challenging problems existing in current food and beverage packaging using paper barrier coating. Furthermore, a stable polymer composite suspension in an aqueous form has many other advantages such as better environmental concern, easier manipulation and better energy saving. However, the research in this area is quite limited in the literature. In this research, a stable water-based suspension of polymer-encapsulated nanoclay composite has been successfully synthesized. The polymer nanocomposites, which encapsulate the exfoliated and well-dispersed nanoclay inside the polymer matrix, can dramatically improve almost all the aspects of mechanical properties and thermal stability in comparison with that of pure polystyrene (PS) and polystyrene butyl acrylate (PSBA) films. The particle size of nanoclay and the surface modification method are two important factors for emulsion stability, the encapsulation and intercalation (or exfoliated) degree of nanoclay. Furthermore, the impact of nanoclay on miniemulsion kinetics has been extensively investigated and the results show the hindrance of nanoclay on styrene miniemulsion polymerization kinetics.

Orientadores: Leila Peres, Jose Luiz Trochmann / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-12T03:11:40Z (GMT). No. of bitstreams: 1 Lucente_AnaGlauciaBogalhos_M.pdf: 1102673 bytes, checksum: b3cbcd44fdb8348cba4293d33498fee3 (MD5) Previous issue date: 2008 / Resumo: A redução no uso de compostos orgânicos voláteis (VOC) é uma demanda ambiental constante. Emulsões poliméricas aquosas com baixo conteúdo de surfactantes, produzidas pela síntese de miniemulsão direta são usadas com vantagens como substitutas a emulsões com solventes orgânicos, assim como a emulsões aquosas com altos teores de surfactantes. A água como fase contínua e monômeros orgânicos com baixa solubilidade em água, são usados. Essas emulsões podem ser termodinamicamente ou cineticamente estabilizadas com agentes surfactantes e ou hidrófobos. Na polimerização por radical livre em miniemulsão o sítio orgânico estabilizado atua como um mini-reator, formando uma dispersão polimérica estável. Dependendo da técnica de preparação utilizada e das taxas de conversão, vários diâmetros médios de partículas (Dp) e distribuição de tamanho (DSD) podem ser obtidos. Das várias técnicas de polimerização em emulsão a miniemulsão se destaca, por poder ser estabilizada cineticamente o que permite reduzir o uso de surfactantes em tipo e quantidade aplicadas, onde as gotículas monoméricas podem ser formadas por cisão da fase orgânica ou por fusão de gotículas ainda menores, cineticamente estabilizadas por agentes surfactantes e ou hidrófobos resultando em nanopartículas. O meio aquoso permite altíssimas taxas de transferência de calor e taxas de transferência de massa adequadas para taxas de polimerização moderadas e altas. Nesse trabalho um polímero acrílico com propriedades físicas específicas para o desenvolvimento de materiais aplicados a área odontológica foi a força motriz na obtenção de um copolímero de metacrilato de metila (MMA) e metacrilato de etila (EMA) dada sua razão de reatividade de 1,08 e 0,98 respectivamente, o que teoricamente leva a obtenção de um copolímero estatístico ou aleatório. O efeito da temperatura (50, 60 e 80°C) na conversão global e na cinética da reação, o Dp e a DSD, a temperatura de transição vítrea (Tg) e a temperatura de fusão (Tf) do copolímero obtido foram estudados por meio de análise gravimétrica, espectrometria de espalhamento de laser (LSS) e calorimetria diferencial de varredura (DSC). O material sintetizado a 60ºC foi também caracterizado com as g/mol. Da caracterização realizada (RMN, FTIR e DSC) foi possível concluir que foi obtido como esperado um copolímero, possivelmente do tipo aleatório ou alternado. técnicas de espectrometria de infravermelho, (FTIR), ressonância magnética nuclear (MNR) para a verificação das funções orgânicas e cromatografia de permeação em gel (GPC) na determinação da massa molar média e sua distribuição. A adição de agente hidrófobo e o uso de ultra-som tornaram possível a obtenção de partículas poliméricas tão pequenas quanto 280nm, com polidispersividade de 1,6 e massa molar média de 2,16 x 106 g/mol. Da caracterização realizada (RMN, FTIR e DSC) foi possível concluir que foi obtido como esperado um copolímero, possivelmente do tipo aleatório ou alternado. / Abstract: Reduction of volatile organic compounds (VOC) usage is a constant environmental demand. Polymeric aqueous emulsion of low surfactant contends produced from direct miniemulsion synthesis are used with advantages to replace organic solvents media as well as aqueous emulsions of high surfactant concentration. Water as continuous phase and organic monomers with low solubility in water are used. This emulsion can be thermodynamically or kinetically stabilized by surfactant agents and / or hydrophobic agents. In free radical miniemulsion polymerization the stabilized organic site acts as a reactor, forming a kinetically stable polymeric dispersion. Depending on the emulsion preparation technique and polymerization rates, at the end of polymerization, several mean particle diameters (Dp) and several size particle distributions (DSD) are possible. Among the emulsion polymerization techniques, miniemulsion polymerization stands out, since kinetic stabilization allows to reduce the need for different types and large amounts of surfactants, where the reaction sites are the monomer droplets formed from scission of the monomer phase or by fusion of even smaller droplets, kinetically stabilized by surfactants and hydrophobic agents resulting in nanoparticles. The water media allow outstanding heat transfer rates as well as mass transfer rates that do not interfere in conversion rates from moderate to high. On this work, a methacrylate polymer based with specific physical properties for the development of materials for Dentistry application, drove the choice of the copolymer obtained from methyl methacrylate (MMA) and ethyl methacrylate (EMA) monomers as they reactivity ratios were: 1.08 and 0.98, respectively, which theoretically would allow obtaining a statistical or random copolymer. Polymerization temperature effect (50, 60 and 80oC) on: overall conversion and kinetic reaction, Dp, DSD, glass transition temperature (Tg) and melting temperature (Tf) of the obtained copolymer, were studied using gravimetric analysis, laser spectrometry spreading (LSS) and differential scanning calorimetry (DSC). The synthesized copolymer at 60o C was also characterized by Fast Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance analysis (NMR) for verification of copolymer organic functions, and gel permeation chromatography (GPC) to determine distribution and mean molar mass. The addition of hydrophobic agent and the use of ultrasound, made possible to obtain volumetric particle diameter as low as 280 nm and polydispersity of 1.60 with average molar mass of 2.16 x 106 g/mol. From the polymer characterization (RMN, FTIR e DSC) it was possible to conclude that a random or alternating copolymer was obtained, as expected. / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

Cette thèse se compose de deux parties. Dans la partie I, nous avons comparé les différences entre les polymérisations en macro- et mini- émulsion. Nous avons établi un modèle de polymérisation en macro-émulsion. Ce modèle peut prédire la distribution de la taille de la chaîne radicalaire pour une classe donnée de tailles des particules. Par comparaison, nous avons établi un modèle de polymérisation en mini-émulsion. Ce modèle peut fournir la distribution des tailles des particules et l'évolution des tailles des gouttelettes. Dans la partie II, afin d'améliorer les propriétés du PP, deux types de monomères ont été utilisés pour être greffés sur PP par extrusion réactive. Ces monomères sont l'anhydride maléique MAH et le silane. Pour améliorer le degré de greffage de MAH sur PP, la montmorillonite organiquement modifiée o-MMT a été utilisée comme un nanoréacteur. Les influences des quantités de MAH et d'initiateur ont été étudiées. Afin d'améliorer le degré de greffage du silane sur PP, les conditions opératoires ont été étudiées. Toutefois, une relation simple entre les propriétés du produit et les conditions de fonctionnement n'a pas pu être trouvée. Pour obtenir le montant le plus élevé de silane greffé sur PP, et en même temps, restreindre les deux réactions secondaires, c'est à dire la polymérisation du silane et la dégradation de la PP chaîne, modèles polynomiaux ont été tentées pour décrire ce processus / This thesis consists of two parts: In Part I, the differences between macro-and mini-emulsion polymerization were compared. A model on macro-emulsion polymerization has been established. This model can predict the radical chain size distribution for a given class of particle sizes. By comparison, a model on mini-emulsion polymerization has been established. This model can provide the particle size distribution and the change of droplets size. In Part II, in order to improve the properties of PP, two kinds of monomers were used to be grafted on PP by reactive extrusion. These monomers were maleic anhydride (MAH) and silane. To improve the grafting degree of MAH on PP, organically modified montmorillonite (MMT) was used as a nanoreactor. The effects of the amounts of MAH and that of initiator were studied. In order to improve the grafting degree of silane on PP, the operating conditions were studied. However, a simple relation between the product properties and the operating conditions could not be found. To obtain the highest amount of silane grafted on PP, and meanwhile, restraining the two side reactions, i.e. the polymerization of silane and the PP chain degradation, polynomial models were attempted to describe this process

Des marqueurs biologiques exogènes à base de nanoparticules hybrides possédant des propriétés optiques non-linéaires ont été préparés en tant qu'agent de contraste pour l'imagerie de second harmonique et le diagnostic de cellules pathogènes. L'iodate de fer est l'un des matériaux proposés dans ce domaine en raison de ses bonnes propriétés de second harmonique et de sa faible toxicité. Des nanoparticules d'iodate de fer ont été synthétisées par microémulsion inverse et miniémulsion inverse. Un bon contrôle de taille et de morphologie des particules a été obtenu dans les deux cas. En vue d'applications biomédicales, l'encapsulation des particules a été réalisée in situ par polymérisation en miniémulsion inverse. Enfin, l'encapsulation de particules de niobate de potassium par un polymère biocompatible a été étudiée. L'intérêt de ces particules hybrides a été démontré par des études in vitro en imagerie de second harmonique. / Exogenous biomarkers based on hybrid nanoparticles with nonlinear optical properties were prepared as a contrast agent for second harmonic imaging and diagnosis of pathogenic cells. Iron iodate is one of the selected materials for this specific field due to its good second harmonic properties and its low toxicity. Iron iodate nanoparticles were synthesized by inverse microemulsion and inverse miniemulsion. In both cases, a good control of size and morphology was achieved. For biomedical applications, nanoparticles encapsulation was carried out in situ by reverse miniemulsion polymerization. Finally, encapsulation of potassium niobate nanoparticles with a biocompatible polymer was conducted. Their interest was demonstrated in vitro by second harmonic imaging studies.