L'objectif de ce travail est de surmonter tous ces processus long et fastidieux comme la filtration et la centrifugation qui sont utilisées dans l'application in-vitro. En plus, ces particules qui sont appropriés pour une utilisation dans le laboratoire-sur une-puce et les biocapteurs systèmes sont produites. Les particules submicroniques magnétiques de latex (MLPs) avec la morphologie noyaucoque souhaité ont été préparées. L'huile dans eau (h/e) et l'émulsion magnétique (faitmaison) a été utilisé en tant que graine de polymérisation radicalaire en émulsion de styrène (St) en tant que monomère et agent de reticulation divenylbenzene (DVB) en présence de persulfate de potassium qu'initiateur. Les particules de la surface ont été fonctionnalisés avec du sulfate et des groupes carboxyliques en utilisant les initiateurs. Un nouveau biocapteur électrochimique de capacité basé sur de substrat de nitrure de silicium (Si3N4) combiné à des MLPs a été développé. MLPs avec terminaison acide carboxylique ont été liés de manière covalente à Si3N4 à travers des monocouches autoassemblées (SAMs) du silane-amine (3-aminopropyl) triéthoxysilane (APTES). Enfin les anticorps anti-ochratoxine A ont été immobilisés sur les MLPs par liaison amide. Mesures électrochimiques ont été effectuées en utilisant une analyse Mott-Schottky pour la détection de l'ochratoxine A (OTA). L'utilisation de l'application de dosage compétitif grà¢ce à l'immobilisation des quantités fixe d'antigène (SA2BSA) et d'anticorps (Ab 155) a été mesurée respectivement contre différentes concentrations de sulfamides pyridine (SPY), avec et sans utilisation de MLPs avec une fonctionnalité de groupe carboxylique. La sensibilité de Biocapteur a augmenté quand MLPs ont été utilisés / Objective of this work is to overcome all those tedious and time consuming processes likefiltration and centrifugation which are used in in-vitro applications. Moreover, suchparticles which are suitable for use in lab-on-a-chip and biosensors systems are produced.Submicron magnetic latex particles (MLPs) with desired core-shell morphology wereprepared. Oil in water (o/w) magnetic emulsion (home-made) was used as seed of radicalemulsion polymerization of Styrene (St.) as a monomer and cross-linker divenylbenzene (DVB ) in the presence of potassium persulfate (KPS) and 4, 4'-azobis cyanopentanoic acid(ACPA) as an initiators. Particles surface was functionalized with sulfate and carboxylicgroups by using the initiators.A novel capacitance electrochemical biosensor based on silicon nitride substrate (Si3N4)combined with MLPs was developed. MLPs with terminated carboxylic acid werecovalently bonded to Si3N4 through a Self-Assembled Monolayers (SAMs) of the silaneamine(3- Aminopropyl) triethoxysilane (APTES). Finally anti-ochratoxin A antibodieswere immobilized on MLPs by amide bonding. Electrochemical measurements werecarried out using Mott-Schottky analysis for ochratoxin A (OTA) detection.Using application of competitive assay through immobilized fixed concentration of antigen (SA2BSA)and antibody (Ab 155) respectively was measured against different concentrations of sulfa pyridine(SPY), with and without use of MLPs with carboxylic group functionality. Biosensor sensitivityincreased, when MLPs were used

La première synthèse d'un carbène N-hétérocylique borane (NHC-borane) stable a été réalisée en 1993. Pourtant la découverte de leur vaste potentiel en chimie n'a réellement débuté qu'à partir de 2007. Les domaines d'application de ces composés du bore, stables et facile d'accès, s'étendent de la synthèse d'organique (réduction d'imine, hydroboration de liaisons multiples, médiateurs radicalaires) à la chimie organométallique (couplage de Suzuki-Miyaura) en passant par la chimie des polymères (amorceurs ou co-amorceurs de photopolymérisation). L'objectif de ce projet aura été d'étendre l'application des NHC-boranes dans deux différents systèmes de photopolymérisation. Le premier système étudié a permis l'obtention de matériaux acrylates contenant des nanoparticules métalliques à partir d'un seul composé dans un processus monotope. Le second système visait l'amorçage de réactions de polymérisation en émulsion sous irradiation visible. Nous avons utilisé le pouvoir réducteur des NHC-boranes pour former des nanoparticules d'or ou d'argent directement dans des monomères acrylates. Puis, la formation par le NHC-borane de la matrice polymère contenant les nanoparticules est déclenchée par une irradiation UV. L'analyse par HRTEM a mis en évidence des petites nanoparticules (ca. 10 nm) emprisonnées dans la matrice. Cette méthode présente une approche encore plus directe pour obtenir ce type de matériau plutôt que les procédés multi-étapes déjà existants. Le second système étudié utilise pour la première fois un NHC-borane comme co-amorceur de la polymérisation du styrène ou du méthacrylate de méthyle en émulsion sous irradiation visible. Il en résulte des latex stables, composés de particules de tailles moyennes contrôlées formés à partir de quantités de tensioactifs inférieures à celles utilisées dans des systèmes photoamorcés déjà décrits. Ces systèmes amorcés par une irradiation visibles pourraient être intéressants pour réduire les coûts énergétiques des synthèses et éviter la dégradation de composés thermo- ou UV- fragiles / Despite the first synthesis of stable N-heterocyclic carbene (NHC)-boranes occurring as early as 1993, the widespread exploration of their potential in chemistry truly began only in 2007. The versatility of these stable and easily accessible boron compounds has led to their application in organic reactions (imine reduction, multiple bond hydroboration, radical reductions), organometallic reactions (Suzuki- Miyaura cross coupling) and polymerization (initiation or co-initiation of polymerization). The aim of my project was to extend the applicability of NHC-boranes to two different photopolymerization systems. The first aimed to synthesize polymer matrices containing metal nanoparticles in a one pot, one reactant process. The second aimed to perform emulsion polymerizations initiated by visible light. In the first system, the reductive capacity of NHC-boranes was used to generate gold or silver nanoparticles directly in acrylate monomers. Then, the initiating ability of NHC-boranes was triggered by UV light to form the polymer matrix containing embedded nanoparticles. Characterization by HRTEM showed small nanoparticles (ca. 10 nm) successfully contained within the matrix. This method represents a more straightforward approach than obtaining such materials through the multistep processes already reported in literature. In the second system, NHC-boranes were employed for the first time as co-initiators in visible light initiated emulsion polymerization styrene and methyl methacrylate. Stable latexes were generated with controllable particle sizes at lower surfactant concentrations than those used in related light-initiated systems. Such visible light-triggered initiation systems are interesting for reducing energy consumption and avoiding degradation of heat- or UV-sensitive materials

Orientador: Liliane Maria Ferrareso Lona / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-27T17:40:21Z (GMT). No. of bitstreams: 1 Bigon_JoicePalma_M.pdf: 3554482 bytes, checksum: 613d2feb1ca89033c773d6e4555ce420 (MD5) Previous issue date: 2015 / Resumo: O estudo das nanocápsulas poliméricas tem crescido significativamente nas últimas décadas em diversas áreas, pois estas permitem a encapsulação de materiais com diferentes princípios ativos, contribuindo com uma ampla variedade de funções que vão desde a liberação controlada de medicamentos e perfumes até a melhora na retenção de pigmentos de tintas para impressão. Uma das técnicas que tem sido utilizada para a síntese das nanocápsulas poliméricas é a polimerização em miniemulsão, que apresenta como uma de suas vantagens a praticidade de se poder utilizar um iniciador organossolúvel ou hidrossolúvel, bem como obter as nanocápsulas poliméricas com um alto grau de eficiência em apenas uma única etapa. Além disso, a polimerização em miniemulsão é conduzida em água, sendo um importante fator quando relacionado ao aspecto ambiental. Entretanto, para se obter uma polimerização em miniemulsão estável, é necessária a adição de um coestabilizador. Muitos artigos na literatura apresentam o hexadecano como um coestabilizador eficiente, uma vez que ele apresenta baixa massa molar e é insolúvel em água. Entretanto, a aplicabilidade das nanocápsulas pode ser aumentada quando materiais biodegradáveis e biocompatíveis são usados. Por isso, neste trabalho foi proposto o estudo de três óleos vegetais (coco, argan e jojoba) como novos coestabilizadores para reações de polimerização em miniemulsão. O óleo de coco é constituído principalmente de ácido láurico, e possui propriedades anti-inflamatórias. O óleo de jojoba é formado principalmente de ésteres, e assim como o óleo de coco, possui propriedades anti-inflamatórias, entre outras. Já o óleo de argan é constituiído principalmente de ácido oleico e linoleico, e possui propriedades muito benéficas para a pele e cabelo. Para as reações de polimerizaçãoem miniemulsão, foi utilizado o iniciador organossolúvel 2,2¿-azobis-isobutironitrila, o monômero metacrilato de metila e o lauril sulfato de sódio como surfactante. Diferentemente da literatura estudada, a polimerização foi realizada em reator tanque agitado de 1 litro de capacidade, e foram estudados os efeitos dos óleos vegetais como coestabilizador na polimerização em miniemulsão de metacrilato de metila. Além disso, foi estudada a distribuição da massa molar, a cinética da reação, a temperatura de transição vítrea bem como o tamanho médio das nanocápsulas poliméricas. A partir dos resultados obtidos, concluiu-se que todos os óleos vegetais atuam como eficientes coestabilizadores, prevenindo o sistema da degradação difusional e da coalescência das gotas / Abstract: The study of polymeric nanocapsules has grown significantly in recent decades in many areas, as they enable the encapsulation of materials with different active ingredients, contributing to a wide variety of functions ranging from the controlled release of drugs and perfumes to the improvement in retention paint pigments for printing. One of the techniques that has been used for the synthesis of polymeric nanocapsules is the miniemulsion polymerization, presenting as one of its advantages the convenience of being able to use either a water or oil soluble initiator, and to obtain the nanocapsules with a high efficiency degree in only one step. Furthermore, miniemulsion polymerization is conducted in water, being an important factor when relating to the environmental aspect. However, to obtain a stable miniemulsion polymerization, adding a co-stabilizer is required. Many articles in the literature cited hexadecane as an efficient co-stabilizer, since it presents low molar mass and it is insoluble in water. However, the applicability of the nanocapsules can be increased when biodegradable and biocompatible materials are used. Therefore, this study proposed the study of three vegetable oils (coconut, argan and jojoba) as new co-stabilizers for polymerization miniemulsion reactions. The coconut oil is composed primarily of lauric acid, and it has anti-inflammatory properties. Jojoba oil is composed primarily of esters, and as coconut oil, presents anti-inflammatory properties, among others. Argan oil is composed mainly of oleic and linoleic acid and it has very beneficial properties for skin and hair. For miniemulsion polymerization reactions, it was used the oil soluble initiator 2¿2-azobisisobutyronitrile, the monomer methyl methacrylate and sodium lauryl sulfate as surfactant. Different from other studies, the polymerization was conducted in stirred tank reactor of 1 liter of capacity, and the effect of the vegetable oils acting as co-stabilizer in the methyl methacrylate miniemulsion polymerization was studied. In addition, the molar mass distribution, the kinetics of the reaction, the glass transition temperature and the average size of the polymeric nanocapsules were studied. It was concluded that the vegetable oils act in the stability of the miniemulsion polymerization, preventing the system from diffusion of monomers and coalescence / Mestrado / Desenvolvimento de Processos Químicos / Mestra em Engenharia Química

No description available.

Les emballages alimentaires et pharmaceutiques doivent de nos jours répondre à de nombreux critères : ils doivent non seulement préserver le produit emballé, mais également être inoffensifs, économes en énergie et jetables. Les polymères barrières ont permis de répondre à ces besoins, en offrant des alternatives à des matériaux plus demandeurs en énergie et plus lourds tels que le verre ou les métaux, tout en conservant une faible perméabilité à l’eau et/ou à l’oxygène. Parmi la grande variété de polymères barrières existants, les copolymères du poly(chlorure de vinylidène) (PVDC) offrent une protection plus complète aux contaminants extérieurs, grâce à leurs faibles perméabilités à l’eau et à l’oxygène. Cependant, les films de PVDC sont sujets à des processus de dégradation ayant lieu lors du thermoformage ou sous exposition aux rayonnements UV. Ces effets sont encore plus prononcés dans le cas de films obtenus à partir de latex, dû à des quantités plus importantes d’additifs qui accentueraient les phénomènes de dégradation du polymère. Par conséquent, la synthèse de latex à base de PVDC pour des applications en tant que films barrières aux stabilités thermique et UV améliorées revêt un grand intérêt. Des latex composites à base de PVDC ont tout d’abord été synthétisés en présence de latex semences à fonctionnalité époxy en vue d’améliorer la stabilité thermique du polymère. En effet, les groupements époxy jouent le rôle de stabilisants thermiques en piégeant le chlorure d’hydrogène, dégagé lors du thermoformage et présentant un effet catalytique indirect sur le processus de dégradation du polymère. Dans une première étape, des latex semences à fonctionnalité époxy ont été synthétisés par copolymérisation en émulsion du methacrylate de glycidyle (GMA) et du methacrylate de butyle (BMA). Lors d’une seconde étape, la copolymérisation en émulsion ensemencée du chlorure de vinylidene et de l’acrylate de méthyle a été effectuée en présence des semences de poly(GMA-co-BMA). Des analyses thermogravimétriques effectuées sur les échantillons composites ont mis en évidence le rôle de stabilisant thermique joué par les fonctions époxy. La seconde partie du projet concerne la synthèse de latex hybrides à base d’oxyde de cérium (CeO2) afin d’améliorer la résistance du PVDC aux rayonnements UV. Les nanoparticules d’oxyde de cérium sont en effet attrayantes en tant que stabilisants UV en raison de leur haute absorption des rayonnements UV et d'une faible activité photocatalytique. Cependant, étant donné l’incompatibilité intrinsèque entre les phases inorganique et organique, la synthèse de latex hybrides requiert souvent une étape préliminaire de modification de surface des particules minérales. Le greffage d’alcoxysilanes a d’abord été entrepris sur des particules d’oxyde de cérium afin d’encourager la réaction de polymérisation à leur surface. Des observations par cryo-Microscopie Electronique à Transmission (cryo-MET) effectuées sur les latex hybrides obtenus par cette stratégie ont montré que le greffage d’alcoxysilanes ne permettait pas d’améliorer efficacement la compatibilité entre les phases inorganique et polymère. Enfin, des macro-agents RAFT amphiphatiques ont été employés comme agents comptabilisant réactifs afin de promouvoir la réaction de polymérisation à la surface de l’oxyde de cérium. Des oligomères RAFT ont été obtenus par des réactions de co- ou terpolymérisation en présence d’un agent de contrôle RAFT. Après caractérisation de l’adsorption des macro-agents RAFT à la surface de l’oxyde de cérium, les particules modifiées ont été utilisées dans des réactions de polymérisation en émulsion. Les observations des latex hybrides par cryo-MET ont confirmé l’efficacité de la méthode pour l’obtention de structures hybrides. Cette stratégie semble ainsi la plus prometteuse pour la synthèse de latex hybrides CeO2/PVDC pour des applications en tant que films barrières présentant une stabilité UV améliorée. / Food and pharmaceutical packages should nowadays fulfill a wide range of requirements : not only should they preserve the packed products from external polluting agents, but they must also be innocuous, more energy-efficient and disposable. Barrier polymers have enabled to meet these criteria, by offering alternatives to more energy-consuming and heavier materials like glass or metals, while maintaining a low permeability to water and/or oxygen. Among the large variety of barrier polymers, poly(vinylidene chloride) (PVDC) copolymers provide a more complete protection to external contaminants, due to their extremely low permeabilities towards water and oxygen. Nonetheless, PVDC films still suffer from limitations as far as their thermal and UV stabilities are concerned. This effect is even more pronounced in the case of films obtained from latexes, due to the presence of higher amounts of additives that could take part in the polymer degradation. Therefore, the synthesis of PVDC-based latexes for use as waterborne barrier films with improved thermal and UV stabilities are of great importance. PVDC-based composite latexes were first synthesized from epoxy-functionalized seed latexes in order to enhance the polymer thermal stability. Given that hydrogen chloride displays an indirect catalytic effect on the polymer degradation, epoxy groups were indeed expected to act as thermal stabilizers by scavenging the HCl released by the polymer under thermal stress. In a first step, epoxy-functionalized seed latexes were synthesized via the emulsion copolymerization of glycidyl methacrylate (GMA) and butyl methacrylate (BMA). In a second step, the seeded emulsion copolymerization of vinylidene chloride and methyl acrylate was carried out in the presence of poly(GMA-co-BMA) seed latexes. Thermogravimetric analyses carried out on the resulting composite samples evidenced the thermal stabilization provided by epoxy groups. The second part of the project focused on the synthesis of cerium oxide-based hybrid latexes so as to improve the stability of PVDC to UV radiation. Cerium oxide (CeO2) nanoparticles are indeed very attractive as UV-stabilizers due to their high absorption of radiation in the UV range and a low photocatalytic activity. However, due to the intrinsic incompatibility between inorganic and polymer phases, the synthesis of inorganic-organic hybrid latexes often requires a preliminary step of modification of the mineral particles surface. The grafting of alkoxysilanes onto nanoceria was first attempted in order to promote the polymerization reaction at the surface of the inorganic particles. Cryo-Transmission Electron Microscopy (cryo-TEM) observations of hybrid latexes obtained via this route showed that this strategy was unsuccessful at improving the compatibility between the inorganic and polymer phases. Amphiphatic macro-RAFT agents were finally considered as reactive compatibilizing agents to direct the polymerization towards the cerium oxide surface. RAFT oligomers were first obtained by co- or terpolymerization reactions in the presence of a RAFT controlling agent. After characterizing the adsorption of amphiphatic macro-RAFT agents at the surface of nanoceria, surface-modified cerium oxide particles were then engaged in reactions of emulsion polymerization reactions. In most cases, cryo-TEM observations carried out on the resulting latexes confirmed the efficiency of the amphiphatic macro-RAFT agent route for the synthesis of hybrid structures. Therefore this route appeared so far to be the most promising for the synthesis of CeO2/PVDC hybrid latexes for use as waterborne barrier films with improved UV-stability.

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

Neste trabalho, estudos da copolimerização em emulsão de estireno e butadieno foram realizados em duas etapas. A primeira etapa consistiu na obtenção de um modelo matemático que representasse os processos em batelada e em semicontínuo através das principais variáveis do processo. Na segunda etapa, o efeito de diversas variáveis importantes ao processo foi avaliado, dentre elas: o tempo de adição dos reagentes, o tipo de alimentação empregado e a temperatura da reação. O modelo matemático se baseia em um trabalho previamente publicado que foi adaptado para simular o processo de copolimerização de estireno e butadieno em emulsão. Foram simulados processos em batelada e em semicontínuo. Em conjunto com os resultados experimentais, foi realizada a estimação de parâmetros não obtidos na literatura utilizando o método de Marquardt. As características do processo e as propriedades do polímero, tais como, conversão, diâmetro de partícula, taxa de polimerização e pressão interna do reator também foram obtidas, fornecendo condições para otimização e avaliação do processo de polimerização em batelada e em semicontínuo. Adicionalmente, também foi proposto um modelo de equilíbrio líquido-vapor dos monômeros. Os ensaios experimentais foram realizados em reator encamisado semicontínuo de mistura com 3 litros, nos quais foram utilizados persulfato de sódio como iniciador, lauril sulfato de sódio como emulsificante e tercdodecil mercaptana como agente de transferência de cadeia. Foram estudados os efeitos da temperatura, do tipo e do tempo de alimentação utilizada. A velocidade de polimerização, os diâmetros médios de partículas, o teor de monômero residual, o teor de insolúveis e o teor de resíduos foram avaliados. A cromatografia gasosa foi aplicada com sucesso em análises de látex e monômeros com finalidades diversas, destacando-se a obtenção de coeficientes de atividade necessários ao modelo de equilíbrio líquido-vapor, análise da concentração de monômeros ao longo da reação e análise da concentração de monômero residual. / In this work, studies of the styrene butadiene emulsion copolymerization had been performed in two stages. The first stage composed of a mathematical model that represented the batch and semi continuous process. In the second stage, the effects of diverse process variables were evaluated, among them: the time of addition of the reagents, feeding type and temperature reaction. The mathematical model was based on previously published work that it was adapted to simulate the styrene butadiene emulsion copolymerization process. Batch and semi continuous processes were simulated. In assembly with the experimental results, Marquardt method was applied to estimate some parameters that wasn’t found in literature. The variable process and the properties of polymer, such as, conversion, particle diameter, rate of polymerization and pressure of the reactor had been also simulated to batch and semicontinous process. A liquid-vapor balance of monomers model was proposed. The experimental stage had been carried through in a semi continuous stirring jacket tank reactor with 3 liters. Sodium persulfate as initiating, sodium lauryl sulfate as surfactant and Tert dodecyl mercaptan as chain transference agent had been used. The effect of temperature, type and time feeding had been studied. Polymerization rate, particles diameter, residual monomer had been evaluated. The gaseous chromatography was successfully applied in analyses of latex with diverse purposes: activity coefficient estimation, adjustment of liquid-vapor model, analysis of residual monomer of the reaction and volatiles organic components concentration in final latex.

Este projeto de mestrado teve como objetivo a obtenção de látices híbridos constituídos de poli(acetato de vinila) (PVAc) e argila montmorilonita (MMT). O homopolímero de acetato de vinila foi sintetizado através da técnica de polimerização em emulsão na presença de diferentes tipos de argila, sendo empregada uma argila sódica (Na-MMT) e três argilas modificadas (o-MMT) com diferentes sais quaternários de amônio. Poli(álcool vinílico) (PVOH) foi utilizado como colóide protetor e persulfato de amônio (APS) como iniciador. Foi estudada a melhor condição para incorporação da argila na matriz polimérica, visando a esfoliação desta nanocarga, resultando desta maneira na formação de nanocompósitos com propriedades diferenciadas. A influência da presença das argilas foi avaliada em termos da velocidade de consumo de monômero, a qual foi acompanhada por gravimetria. Os látices foram caracterizados quanto ao diâmetro médio de partícula e polidispersidade pela técnica de espalhamento de luz (LS). O teor de coágulos do látex foi calculado por análise gravimétrica e a viscosidade analisada em um viscosímetro rotacional. Os filmes nanocompósitos foram caracterizados pelas técnicas de análise dinâmico-mecânica (DMA), análise termogravimétrica (TGA) e difração de raios X (DRX). A morfologia das partículas de látex foi avaliada por microscopia eletrônica de transmissão (MET). / The goal of this project was the preparation of hybrids latexes constituted by poly(vinyl acetate) (PVAc) and montmorillonite (MMT) clays. The poly(vinyl acetate) homopolymer was synthesized via emulsion polymerization in the presence of different types of clay, one sodium clay (Na-MMT) and organically modified clays (o-MMT) with different ammonium quaternary salts. Poly(vinyl alcohol) (PVOH) was used as protective colloid and ammonium persulfate (APS) as initiator. It was evaluated the best condition for the incorporation of the clay in the polymeric matrix, looking forward the exfoliation of the nanofiller, resulting in the formation of nanocomposites with new and improved properties. The influence of clay type and loading was evaluated in terms of latex stability and monomer consumption rate. The latexes were characterized in terms of particle size diameter and polydispersity by light scattering (LS) technique. Coagulum content was determined by gravimetric analysis and viscosity was analyzed in a rotational viscometer. Nanocomposite films were characterized by dynamic-mechanical analysis (DMA), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). Latex particles morphology was evaluated by transmission electron microscopy (TEM).

Neste trabalho são apresentadas estratégias para a estimação, em processos químicos, de estados, parâmetros e covariâncias do ruído de processo e das medidas que são testadas com dados experimentais. Para a estimação de estados e parâmetros foram implementadas desde a técnica mais tradicional, o filtro estendido de Kalman (EKF) até as mais modernas da literatura, como o filtro de Kalman Unscented (UKF) e o Moving Horizon Estimator (MHE). A técnica Autocovariance Least-Squares (ALS) permite a estimação das matrizes de covariância do processo e das medidas a partir dos estados medidos dos processos analisados. Três processos foram analisados com as técnicas citadas: a reação de hidrólise de anidrido acético, o aquecimento de um reator de polimerização completamente carregado (sem iniciador) e por fim oito reações diferentes de polimerização em emulsão. Os resultados mostraram que uma sintonia por tentativa e erro para as matrizes de covariância não apresenta um desempenho adequado. Adicionalmente, o UKF mostra um melhor desempenho, quando comparado com o EKF para o monitoramento de processos de polimerização regime em batelada com covariâncias obtidas através de otimização direta. Quando a estimação da covariância com a técnica ALS é implementada e os resultados utilizados em estimadores estocásticos, o desempenho dos estimadores recursivos melhora consideravelmente. Além disso, o MHE mostrou ser uma ferramenta robusta para o monitoramento do coeficiente global de troca térmica (UA) e do calor gerado pela reação para a polimerização em emulsão em regime semi-contínuo. Finalmente, duas características vantajosas da metodologia proposta devem ser destacadas: a independência em relação ao valor inicial para o estado UA e o fato de um único conjunto de matrizes de covariância (quando obtida pela técnica ALS) poder ser utilizado em reações diferentes, sem necessidade de sintonizar novamente as matrizes para cada reação. / In this work, strategies for state, parameter and covariance estimation in chemical processes are presented and tested with experimental data. For state and parameter estimation techniques have been implemented that spread from the traditional Extended Kalman Filter (EKF) to the most modern techniques from literature, such as the Unscented Kalman Filter (UKF) and the Moving Horizon Estimator (MHE). The Autocovariance Least-Squares technique (ALS) allows the covariance matrices of the process and measurement noise to be estimated based on the measured states of the processes analyzed. Three cases were studied using these techniques: the hydrolysis of acetic anhydride, the warming-up stage of a fully charged polymerization reactor (without initiator) to the desired temperature and finally, eight different emulsion polymerization reaction runs. Results showed that determining covariance matrices by trial and error does not lead to an adequate performance. Additionally, the UKF presents a better performance than the EKF for batch polymerization processes with covariance matrices obtained by direct optimization. When the estimation of the covariance is performed by the ALS technique and they are used in a stochastic estimator, the performance of the recursive estimators is considerably improved. Furthermore, the MHE proved to be a robust tool for monitoring the overall heat transfer coefficient (UA) and the heat of reaction for fedbatch emulsion polymerization. Finally, two positive features of the proposed methodology must be highlighted, its low dependency on the initial state condition of UA and the fact that a unique set of covariance matrices (when obtained by the ALS technique) can be used for different reaction runs, without the necessity of tuning the matrices again for each reaction.

A crescente demanda por produtos poliméricos com propriedades cada vez mais estritas tem forçado o desenvolvimento de técnicas de monitoramento em linha cada vez mais precisas e robustas. Infelizmente, grande parte das principais propriedades poliméricas não são quantificáveis em linha a partir das metodologias analíticas atualmente disponíveis e, portanto, na prática, as propriedades finais dos látices poliméricos são obtidas através da caracterização off line de amostras discretas coletadas do processo, resultando em um tempo de análise longo e indesejado para qualquer algoritmo de controle em tempo real. Por outro lado, como as reações de polimerização são altamente exotérmicas é possível quantificar continuamente a taxa de calor gerado pela reação a partir das medidas de temperatura e do balanço de energia que, por sua vez, pode ser usada para obter importantes informações acerca do estado do processo. Entretanto, esta técnica requer a atualização contínua do coeficiente global de troca térmica ao longo da reação, uma vez que este parâmetro está sujeito a variações temporais significativas. Portanto, o presente trabalho tem por objetivo analisar a viabilidade da aplicação conjunta dos conceitos da calorimetria e dos observadores não-lineares para a estimação dos estados de um processo químico. Para isso, serão analisadas duas reações químicas distintas: a) uma reação de hidrólise de anidrido acético, b) uma reação copolimerização em emulsão. Os resultados obtidos mostraram que essa metodologia é extremamente dependente dos parâmetros de sintonia do observador de estado, inviabilizando o seu uso para o monitoramento em linha de um processo químico. Por outro lado, a aplicação direta do balanço de energia para estimação do calor gerado pela reação, mostrou-se uma forma alternativa simples e viável para a estimação em tempo real dos estados de uma reação de polimerização. / The increasing demand for the production of polymers with more tight properties has placed great emphasis on the development of accurate and robust online monitoring techniques of polymerization reactions. Unfortunately, most of the main characteristics are not measurable online from analytical methodologies currently available and, therefore, in practice, the final properties of polymer latexes are obtained through off line characterization of discrete samples collected from the process, resulting in measurement delay which is undesirable for real-time control. On the other hand, since most of the polymerization reactions are highly exothermic, it is possible to quantify continuously the heat release rate based on temperature measurements and energy balance equations that, in turn, can be used to infer valuable information about the state of process. However, this approach requires up-dating the value of the global heat exchange coefficient through reaction, once this parameter is subject to significant time variations. Therefore, this work aims to examine the feasibility of joint implementation of the concepts of reaction calorimetry and nonlinear state observers for estimation of the states of a chemical process. In order to do that, two distinct chemical reactions will be considered: a) a hydrolysis of acetic anhydride reaction, b) an emulsion copolymerization reaction. The results showed that this approach shows a strong dependence of the tuning parameters, preventing its use for online monitoring of a chemical process. On the other hand, applying the heat balance it is possible to infer continuously the heat release rate and the states of polymerization reactions.