Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-03-14T21:09:10Z No. of bitstreams: 1 RafaelAraujoDaSilva_DISSERT.pdf: 1302282 bytes, checksum: cb4d89880b246386e0981baae0eea668 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-03-15T21:55:04Z (GMT) No. of bitstreams: 1 RafaelAraujoDaSilva_DISSERT.pdf: 1302282 bytes, checksum: cb4d89880b246386e0981baae0eea668 (MD5) / Made available in DSpace on 2017-03-15T21:55:04Z (GMT). No. of bitstreams: 1 RafaelAraujoDaSilva_DISSERT.pdf: 1302282 bytes, checksum: cb4d89880b246386e0981baae0eea668 (MD5) Previous issue date: 2015-01-29 / Os fluidos de perfura??o aquosos s?o os sistemas mais utilizados no mundo para a perfura??o de po?os petrol?feros, tendo sido, nas ?ltimas d?cadas, desenvolvidas excelentes formula??es para perfura??o de se??es iniciais com baixa temperatura e baixa press?o. No entanto, as reservas de petr?leo nessas condi??es est?o cada vez mais escassas, surgindo a necessidade operacional de atua??o em condi??es mais severas, ou seja, vem sendo relatada na literatura a necessidade de sistemas aquosos para atua??o em altas temperaturas e altas press?es (ATAP). As altas temperaturas dos po?os de petr?leo favorecem a degrada??o qu?mica dos pol?meros (aditivo comumente presente nas formula??es relatadas, atualmente, na literatura e aplicados em situa??es operacionais), podendo promover a redu??o da massa molar e perdas de viscosidade do sistema. Os microg?is podem ser aplicados em v?rios seguimentos da ind?stria, com destaque na ?rea do petr?leo, situa??o que s?o aplicados na estimula??o de po?os e na recupera??o avan?ada de petr?leo (EOR). Neste trabalho, a aplicabilidade de microg?is de hidroxipropilguar (HPG), obtidos por reticula??o do HPG com ?ons borato, foi avaliada quanto ? resist?ncia t?rmica em fluidos de perfura??o aquosos. A aplica??o de microg?is de HPG no fluido de perfura??o base ?gua aumentou a viscosidade aparente e reduziu o volume de filtrado na temperatura ? 25?C. Entretanto, com o aumento da temperatura para 50 ?C ocorreu redu??o da viscosidade aparente de 85 mPa.s para 25,45 mPa.s. Esses resultados indicam que o emprego de microg?is em fluidos de perfura??o aquosos pode ser uma alternativa promissora, desde que o agente reticulante seja adequadamente selecionado, ou seja, n?o sofra desativa??o com o aumento da temperatura e n?o seja influenciado pela salinidade do meio. / Aqueous drilling fluids are a widely used systemin the world to drill oil wells. This drilling system has been being developed excellent formulations for drilling initial sections with low temperature and low pressure in recent decades. However, the oil reserves in these conditions are increasingly scarce, ending up in the need for drilling fluids with better operational performance in the toughest conditions. Therefore, it has been reported in the literature the need for aqueous systems to operate at high temperatures and high pressures (HTHP). High temperatures of oil wells favor the chemical degradation of polymers (commonly reported in additive formulations currently in the literature and applied in operational situations), that can generate molecular weight reduction and viscosity losses. Microgels can be applied in vast industrie`s segments, highlighted in the oil field, as they are used in the estimulation of wells and in the Advanced Oil Recovery (EOR). In this work, the applicability of hydroxypropyl guar`s microgels (HPG), obtained by crosslinking the HPG with borate ions, was measured as the thermal stability in water based drilling fluids.The application HPG microgels in water-based drilling fluid has increased viscosity and the apparent volume of the filtrate reduced around 25 ? C. However, with the increase of temperature to 50 ?C, the viscosity of drilling fluids based on HPG microgels decreased from 85 mPa.s to 25,45 mPa.s. These results indicate that the use of microgels in aqueous drilling fluids is a promising alternative since the crosslinking agent has been properly selected, i.e., does not undergo deactivation with increasing temperature and is not affected by the salinity of the system.

[ES] El mieloma múltiple es una neoplasia hematológica caracterizada por una expansión descontrolada de células plasmáticas monoclonales (mPCs) en medula ósea que producen, en la mayoría de los casos, un componente monoclonal secretado en el suero y/o en orina. En la actualidad, se sigue considerando una enfermedad incurable con la constante aparición de recaídas en los pacientes. Una de las causas que condicionan esta situación, radica en la generación de resistencia frente a fármacos por parte de las mPCs. Este mecanismo de resistencia a fármacos (DR) se ha visto que no solo depende de factores intracelulares, sino que la propia interacción de las mPCs con el microambiente medular juega un papel fundamental para su supervivencia, crecimiento y desarrollo de DR. Entre los componentes del microambiente tumoral, destaca la adhesión de las mPCs a componentes de la matriz extracelular (ECM) que se ha visto relacionada con la generación de DR. Por este motivo el desarrollo de esta tesis doctoral consistió en la elaboración y validación de una plataforma de cultivo 3D basado en la síntesis de un microgel. Este sistema estará constituido por microesferas funcionalizadas con componentes de la ECM como son la fibronectina (FN), colágeno tipo I (COL), heparina (Hep), heparan sulfato (HS) y ácido hialurónico (HA), generando un entorno 3D biomimético con la capacidad de poder analizar la respuesta celular desencadenada por la interacción de las mPCs con los componentes de la ECM, así como la DR generada por la adhesión de las mPCs a estas biomoléculas. El primer estudio consistió en la realización y puesta a punto de varios protocolos para la síntesis de distintos microgeles; un primer sistema se produjo mediante la polimerización por vía radical en bloque de co-polímeros de poliacrilato de etilo (EA) y polimetacrilato de etilo (EMA) o bien por EA, EMA y ácido acrílico (AAc). Mediante una emulsión del tipo aceite en agua se consiguió producir con estos copolímeros, microesferas de un tamaño próximo al de las mPCs. Un segundo sistema se basó en microesferas de alginato. Estas microesferas se obtuvieron en un dispositivo de microfluidica produciéndose la gelificación externa de las micro-gotas con la incorporación de iones de calcio consiguiendo microesferas de un tamaño medio de 177 µm. Debido a la gran variedad de microesferas sintetizadas con diferentes grupos químicos en sus superficies, se consiguió establecer protocolos de funcionalización similares a los establecidos en la literatura, teniendo en cuenta la estabilidad de la biomolécula a lo largo del tiempo del cultivo celular. Este enfoque, permitió la funcionalización con una gran variedad de biomoléculas disponiendo así de microgeles funcionalizados con FN, COL, Hep, HS y HA. Una vez desarrollados los microgeles, en un segundo estudio se procedió a evaluar la respuesta celular en un entorno 3D basado en microgel, valorando la interacción con los componentes de la ECM. Entre los resultados observados se pudo determinar como el tamaño de las microesferas afecta al crecimiento celular incluso en ausencia de cualquier funcionalización. Con los microgeles constituidos por microesferas de un tamaño próximo al de las mPCs se obtuvo un mayor crecimiento celular que con los microgeles formados por partículas de mayor tamaño, y en ambos el crecimiento fue superior al del cultivo en suspensión. Se plantea la hipótesis de que la presencia de las microesferas favorece en gran medida que se produzca un mayor contacto célula-célula que se ve incrementado cuanto mayor es la superficie específica del microgel. Entre los componentes de la ECM estudiados, mientras que el COL no genera ninguna respuesta celular diferente al control (microgel no funcionalizado), el HA favorece la proliferación celular. La adhesión de las mPCs a la FN condiciona el bloqueo de las células en la fase G0-G1 del ciclo celular. Esta adhesión está mediada / [CA] El mieloma múltiple és una neoplàsia hematològica caracteritzada per una expansió descontrolada de cèl·lules plasmàtiques monoclonals (mPCs) en medul·la òssia que produeixen, en la majoria dels casos, un component monoclonal secretat en el sèrum i/o en orina. En l'actualitat, es continua considerant una malaltia incurable, amb la constant aparició de recaigudes en els pacients. Una de les causes que condicionen aquesta situació, radica en la generació de resistència enfront de fàrmacs per part de les mPCs. Aquest mecanisme de resistència a fàrmacs (DR) s'ha vist que no sols depèn de factors intracel·lulars, sinó que la mateixa interacció de les mPCs amb el microambient medul·lar juga un paper fonamental per a la seua supervivència, creixement i desenvolupament de DR. Entre els components del microambient tumoral, destaca l'adhesió de les mPCs a components de la matriu extracel·lular (ECM) que s'ha vist relacionada amb la generació de DR. Per aquest motiu, el desenvolupament d'aquesta tesi doctoral va consistir en l'elaboració i validació d'una plataforma de cultiu 3D basada en la síntesi d'un microgel. Aquest sistema estarà constituït per microesferes funcionalitzades amb components de l'ECM com són la fibronectina (FN), col·lagen tipus I (COL), heparina (Hep), heparan sulfat (HS) i àcid hialurònic (HA), generant un entorn 3D biomimètic amb la capacitat de poder analitzar la resposta cel·lular desencadenada per la interacció de les mPCs amb els components de la ECM, així com la DR generada per l'adhesió de les mPCs a aquestes biomolècules. El primer estudi va consistir en la realització i posada a punt de diversos protocols per a la síntesi de diferents microgels; un primer sistema es va produir mitjançant la polimerització per via radical en bloc de copolímers de poliacrilat d'etil (EA) i polimetacrilat d'etil (EMA), o bé per EA, EMA i àcid acrílic (AAc). Mitjançant una emulsió del tipus oli en aigua es va aconseguir produir amb aquests copolímers, microesferes d'una grandària pròxima al de les mPCs. Un segon sistema es va basar en microesferes d'alginat. Aquestes microesferes es van obtenir en un dispositiu de microfluidica produint-se la gelificació externa de les microgotes amb la incorporació d'ions de calci aconseguint microesferes d'una grandària mitjana de 177 ¿m. A causa de la gran varietat de microesferes sintetitzades amb diferents grups químics en les seues superfícies, es va aconseguir establir protocols de funcionalització similars als establerts en la literatura, tenint en compte l'estabilitat de la biomolècula al llarg del temps del cultiu cel·lular. Aquest enfocament va permetre la funcionalització amb una gran varietat de biomolècules disposant així de microgels funcionalitzats amb FN, COL, Hep, HS y HA. Una vegada desenvolupats els microgels, en un segon estudi es va procedir a avaluar la resposta cel·lular en un entorn 3D basat en microgel, valorant la interacció amb els components de l'ECM. Entre els resultats observats es va poder determinar com la grandària de les microesferes afecta el creixement cel·lular fins i tot en absència de qualsevol funcionalització. Amb els microgels constituïts per microesferes d'una grandària pròxima al de les mPCs es va obtenir un major creixement cel·lular que amb els microgels formats per partícules de major grandària, i en tots dos el creixement va ser superior al del cultiu en suspensió. Es planteja la hipòtesi que la presència de les microesferes afavoreix en gran manera que es produïsca un major contacte cèl·lula-cèl·lula que es veu incrementat com més gran és la superfície específica del microgel. Entre els components de l'ECM estudiats, mentre que el COL no genera cap resposta cel·lular diferent del control (microgel no funcionalitzat), l'HA afavoreix la proliferació cel·lular. L'adhesió de les mPCs a la FN condiciona el bloqueig de les cèl·lules en la fase G0-G1 del cic / [EN] Multiple myeloma is a haematological neoplasm characterized by an uncontrolled expansion of monoclonal plasma cells (mPCs) in bone marrow that produce, in most cases, a monoclonal component secreted in serum and/or urine. At present, it is still considered an incurable disease with the constant appearance of relapses in patients. One of the causes that condition this situation lies in the generation of drug resistance by the mPCs. This mechanism of drug resistance (DR) has been seen to depend not only on intracellular factors, but the very interaction of mPCs with the medullary microenvironment plays a fundamental role in their survival, growth and development of DR. Among the components of the tumor microenvironment, the adhesion of the mPCs to components of the extracellular matrix (ECM) stands out, which has been related to the generation of DR. For this reason, the development of this doctoral thesis consisted in the elaboration and validation of a 3D culture platform based on the synthesis of a microgel. This system will be made up of micropsheres functionalized with the components of the ECM such as fibronectin (FN), collagen type I (COL), heparin (Hep), heparan sulphate (HS) and hyaluronic acid (HA), generating a 3D biomimetic environment with the ability to analyse the cellular response triggered by the interaction of mPCs with the ECM components, as well as the DR generated by the adhesion of the mPCs to these biomolecules. The first study consisted in the realization and development of several protocols for the synthesis of different microgels. A first system was produced by the radical block polymerization of polyethylene acrylate (EA) and polymethacrylate (EMA) co-polymers or by EA, EMA and acrylic acid (AAc). By means of an oil-in-water emulsion technique, it was possible to produce, with these copolymers, microspheres of a size close to that of the mPCs. A second system was based on alginate microspheres. These microspheres were obtained in a microfluidic device producing the external gelification of the micro-drops with the incorporation of calcium ions, obtaining microspheres with an average size of 177 µm. Due to the great variety of microspheres synthesized with different chemical groups on their surfaces, it was possible to establish functionalization protocols similar to those established in the literature, taking into account the stability of the biomolecule along with the time of cell culture. This approach allowed for functionalization with a great variety of biomolecules, having in this way functionalized microgels with FN, COL, Hep, HS and HA. Once the microgels were developed, a second study was carried out to evaluate the cell response in a 3D microgel-based environment, assessing the interaction with the components of the ECM. Among the results observed, it was possible to determine how the size of the microspheres affects cell growth even in the absence of any functionalization. With the microgels constituted by microspheres close to the size of the mPCs, a greater cellular growth was obtained than with the microgels formed by larger particles, and in both the growth was higher than in suspended culture. It is hypothesized that the presence of microspheres greatly favours a greater cell-cell contact, which is increased the larger the specific surface area of the microgel. Among the components of the ECM studied, while the COL does not generate any cellular response different from the control (non-functionalized microgel), HA favours cell proliferation. The adhesion of mPCs to FN conditions the blocking of cells in the G0-G1 phase of the cell cycle. This adhesion is mediated by the integrin ¿4ß1. / La presente tesis doctoral no se podría haber realizado sin la financiación del proyecto PROMETEO/2016/063, trabajo que también estuvo parcialmente financiado con fondos FEDER (CIBERONC (CB16/12/00284)). La iniciativa CIBER-BBN está financiada por el proyecto VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program. Las acciones CIBER están financiadas por el Instituto de Salud Carlos III con ayuda del Fondo Europeo de Desarrollo Regional. / Marin Paya, JC. (2021). 3D Culture o Multiple Myeloma Cell Line Using Microgel Environments [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/167427 / TESIS

Les revêtements polymères stimuli-sensibles permettent d'ajuster les propriétés de surface par des stimuli externes (i.e. des variations des conditions environnementales) via des changements dans leur conformation physique, la chimie de surface, ou les deux. Cette capacité permet leur utilisation comme éléments fonctionnels dans les nanotechnologies tels que des valves dans les dispositifs microfluidiques, comme lubrifiants, ou comme substrats pour la culture de tissus biologiques. Cependant, de tels revêtements souffrent généralement d'un inconvénient majeur, afin de déclencher un changement de la conformation physique du revêtement polymère (gonflement) via un stimulus, il est nécessaire de changer au moins une de ses propriétés physico-chimiques qui produit des variations simultanées des propriétés de surface (i.e. potentiel de surface, adhésion). Ce travail vise à surmonter cette limitation en étudiant une nouvelle génération de revêtements hiérarchiques fonctionnels dont les propriétés physiques et la chimie de surface peuvent être modulées indépendamment et de manière réversible en utilisant différents stimuli tels que la température et le pH. Les revêtements hiérarchiques sont constitués de matrices des microgels à base de poly-(N-isopropylacrylamide) bidimensionnelles fonctionnalisés en surface avec des polymères dont les dimensions caractéristiques et les propriétés de surface peuvent être contrôlées indépendamment par différents stimuli en fonction des propriétés de surface souhaitées. Ce travail démontre que les dimensions caractéristiques (i.e. diamètre hydrodynamique, épaisseur de couche) peuvent en effet être contrôlées sans affecter les propriétés de surface (i.e. potentiel de surface, adhérence) des réseaux de microgels fonctionnalisés. La réactivité des revêtements fonctionnels a été étudiée à l'aide de la Diffusion Dynamique de la Lumière et de l'Appareil de Forces de Surface permettant de déterminer avec précision l'adhésion, la friction, le potentiel de surface, le diamètre hydrodynamique et l'épaisseur de la couche sous différents stimuli. Enfin, la capacité de ces substrats fonctionnels pour produire un détachement cellulaire déclenché par des stimuli dans le cadre de la culture cellulaire a été étudiée. / Stimuli-responsive polymer coatings enable surface properties to be tuned by external stimuli (i.e. variations of environmental conditions) via changes in their physical conformation, surface chemistry, or both. This capacity enables their use as functional elements in nanotechnologies such as valves in microfluidic devices, as lubricants, or as substrates for culture of biological tissues. However, such coatings usually suffer from a major shortcoming, in order to trigger a change in the physical conformation of the polymer coating (swelling) via a stimulus, it is necessary to change at least one of its physicochemical properties which results in simultaneous variations of the surface properties (i.e. surface potential, adhesion). The present work aims to overcome this limitation by investigating a new generation of responsive hierarchical coatings whose physical properties and surface chemistry can be tuned independently and reversibly using different stimuli such as temperature and pH. The hierarchical coatings consist of two-dimensional poly-(N-isopropylacrylamide) microgel arrays surface-functionalized with polymers whose characteristic dimensions and surface properties can be independently controlled by different stimuli according to the desired surface properties. This work shows how the characteristic dimensions (i.e. hydrodynamic diameter, layer thickness) can indeed be controlled without affecting the surface properties (i.e. surface potential, adhesion) of the functionalized microgel arrays. The responsiveness of the functional coatings was investigated using Dynamic Light Scattering and the Surface Forces Apparatus allowing adhesion, friction, surface potential, hydrodynamic diameter, and layer thickness to be accurately determined under different stimuli. Finally, the ability of these coatings as functional substrates to produce stimuli-triggered cell detachment during cell culture was studied.

Les écoulements de suspensions dans des milieux poreux sont particulièrement complexes, notamment à cause du couplage d’écoulements de cisaillement et d’écoulements élongationnels (Herzig, Leclerc et Goff, 1970). On les retrouve fréquemment dans les applications industrielles, l’une des applications principales se trouvant lors des opérations de production de pétrole et de gaz. Lors de la construction d'un puits, des additifs polymères anti perte de fluide empêchent à plusieurs étapes l'écoulement de fluide entre le puits et la formation de roche poreuse environnante. La perte de fluide est un problème grave si elle n’est pas maîtrisée ; elle s’ajoute alors au coût total des opérations et pourrait surtout avoir des conséquences néfastes pour l’environnement et les opérateurs. Parmi les technologies disponibles, des additifs polymères connus sous le nom d'additifs anti perte de fluide, tels que des microgels et des particules de latex, sont ajoutés aux fluides injectés pour limiter les pertes de fluide (généralement de l'eau) via un mécanisme de colmatage / blocage de pores du support poreux.Le comportement de blocage de beaucoup de ces additifs anti perte de fluide a été testé par des méthodes conventionnelles qui impliquent l'application d'une différence de pression élevée (typiquement 35-70 bars) sur le fluide formulé comprenant les additifs contre un filtre représentatif de la taille typique des pores de la formation (une grille métallique, de la céramique ou du papier filtre) et la mesure du volume de filtrat en fonction du temps. Cependant, ces méthodes standard ne permettent pas de comprendre le mécanisme sous-jacent de la dynamique de blocage des supports poreux. Par conséquent, une meilleure compréhension du mécanisme de blocage d’un support poreux par des additifs industriels anti perte de fluide est nécessaire.Dans ce travail, nous utilisons des suspensions de microgels réticulés chimiquement comme additifs anti perte de fluide et nous étudions leur comportement de blocage dans des milieux poreux modèles transparents. Nous utilisons des dispositifs à base de polydiméthylsiloxane (PDMS) comme modèle de support poreux permettant l'observation directe du processus de blocage couplée à des mesures quantitatives. Nous fabriquons des dispositifs microfluidiques de filtration frontale et de filtration latérale avec différentes tailles de pores afin de déterminer comment des paramètres tels que la mouillabilité de la surface, la concentration en particules, la taille des particules et le débit affectent la formation du gâteau de filtration.Nous présentons une méthode de contrôle de la taille des particules constituant les suspensions de microgels. Nous décrivons ensuite une approche pour préparer des suspensions à plus haute concentration et étudions la rhéologie des suspensions en fonction de la concentration en particules. De plus, nous présentons un procédé simple pour former un gâteau de filtration à partir de la suspension de microgels sur une membrane et estimons la perméabilité à l’eau du gâteau de filtration formé selon la loi de Darcy. / The flow of suspensions in porous media is a complex phenomenon due to the mechanisms involved such as both shear and extensional flows (Herzig, Leclerc, & Goff, 1970). Their use in industrial applications is quite extensive with one of the major applications being at various stages of oil and gas production operations. At several stages of a well construction, flow of fluid between the well and the surrounding porous rock formation is prevented thanks to the polymeric fluid loss control additives. Fluid loss is a severe problem if not controlled, which would add up to the total cost of operations and more importantly could have hazardous impacts on the environment or operators. Among several technologies industrially available, polymeric additives popularly known as fluid loss additives such as microgels and latex particles are added to the injected fluids to limit the loss of fluid (usually water) via the mechanism of pore clogging/jamming in porous media.Many of these fluid loss additives have been tested for their jamming behaviour by conventional methods which involve the application of a high pressure difference (typically 35-70 bars) on the formulated fluid comprising of the additives against a filter representative of the formation’s typical pore size (either a metallic grid, ceramic or filter paper) and the measurement of the filtrate volume versus time. However, these standard methods do not give any insight in understanding the underlying mechanism of jamming dynamics in porous media, hence, a better understanding of the mechanism of jamming in porous media by industrial fluid loss additives is needed.In this work, we use chemically cross-linked microgel suspensions as the fluid loss additive and study its jamming behaviour in transparent model porous media. We make use of polydimethylsiloxane (PDMS) devices as model porous media which allows direct observation of the jamming process coupled with quantitative measurements. We fabricate microfluidic devices for frontal flow filtration and lateral flow filtration with different pore sizes to see how parameters like surface wettability, particle concentration, particle size and flow rates affect the filter cake formation.We present a method of controlling the size of the microgel suspensions. We then describe an approach for preparing higher concentration suspensions and investigate the rheology of the suspensions as a function of concentration. Furthermore, we present a simple method of forming a filter cake of the microgel suspension on a supporting membrane and estimate the permeability of the filter cake formed for the flow of water using Darcy’s law.

Esta tese apresenta os estudos realizados quanto à síntese e caracterização de microgéis termo-responsivos de N-isopropilacrilamida (NIPAM) e macromoléculas de origem amilácea em sua composição, sistemas ainda pouco explorados na literatura. Inicialmente, nanopartículas de amido (SNP) foram preparadas por nanoprecipitação para incorporação nos microgéis de interesse, através da dissolução dos grânulos do amido em DMSO/H2O, aplicação de ultrassom e precipitação em não-solvente. As SNPs preparadas foram utilizadas como copolímero para formação de microgéis híbridos do tipo SNP-co-p(NIPAM) através de polimerização em emulsão na presença e na ausência de surfactante. A influência das SNPs nas propriedades dos microgéis foi estudada por MEV, DLS, PZ e SAXS, onde foram observadas mudanças no comportamento físico-químico e estrutura supramolecular dos microgéis. No geral, observaram-se deslocamentos da temperatura de transição de fase para valores maiores (até 35 °C, cerca de 3 °C acima do valor determinado para sistemas contendo p(NIPAM) puro), aumento da estabilidade coloidal e organização dos polímeros presentes no microgel em uma arquitetura caroço-casca. As propriedades de inchamento dos microgéis também foram estudadas através da teoria de Flory-Rehner, onde a temperatura theta e o grau de polimerização entre dois pontos de reticulação foram determinados através do ajuste apropriado do parâmetro de interação (χ). Paralelamente, visando um sistema diferente do descrito acima, foi estudado um novo agente de reticulação baseado nos polímeros do amido, a amilose e a amilopectina. Para isso, os polímeros do amido que compõem as nanopartículas foram modificados para a utilização como agente de reticulação na síntese de microgéis de p(NIPAM). Nesta etapa, uma reação de substituição dos grupos hidroxila dos polímeros do amido foi realizada com o cloreto de acriloíla de forma a inserir insaturações na estrutura dos polímeros, para que estes fossem aplicados como reticulante. O sucesso da reação de modificação foi verificado através de RMN 1H e FTIR, no qual um maior grau de substituição foi obtido quando um tempo maior de reação foi empregado. Microgéis de p(NIPAM) foram então preparados através de polimerização em emulsão utilizando os reticulantes sintetizados. Observou-se a influência do grau de substituição e da concentração do reticulante nos microgéis, analisados por MEV, DLS e UV-Vis com controle de temperatura. As principais mudanças foram relativas à temperatura de transição de fase e tamanho dos microgéis. Utilizando o agente de reticulação com maior grau de substituição, foi possível deslocar a temperatura de transição de fase dos microgéis preparados para valores maiores (35 °C, cerca de 3 °C acima do valor determinado para sistemas contendo p(NIPAM) puro). Observou-se também uma resposta mecânica da rede do microgel, que refletiu no tamanho das partículas, influenciada pela concentração dos agentes de reticulação e do grau de substituição. Quanto maior a concentração e o grau de substituição do agente de reticulação, maior a resistência ao intumescimento observado no microgel. / This thesis presents the studies regarding the synthesis and characterization of thermoresponsive microgels of N-isopropylacrylamide (NIPAM) and amylaceous-based macromolecules, which are systems still little explored in the literature. At first, starch nanoparticles (SNP) were prepared by nanoprecipitation, through dissolution of starch granules in DMSO/H2O, ultrasound application and non-solvent precipitation. SNPs were then used as copolymer in SNP-co-p(NIPAM) hybrid microgels synthesized by emulsion polymerization in the presence and absence of surfactant. The influence of SNPs in microgel properties were studied by SEM, DLS, ZP, and SAXS, where changes in the physicalchemical behavior and supramolecular structure were observed. Summing up, shifts in the phase transition temperature up to 35 °C, increased colloidal stability, and microgel polymers organization into a core-shell structure were observed. Microgels swelling behaviour were also studied by the Flory-Rehner theory, where the theta-temperature and the degree of polymerization between two crosslinker points were determined through interaction parameter (χ) fitting. In parallel, a new starch-based crosslinker was studied. For this purpose, starch polymers (amylose and amylopectin within the SNPs) were modified in order to use them as crosslinker in p(NIPAM) microgel synthesis. In this step, a substitution reaction in hydroxyl groups of SNP was carried out with acryloyl chloride, where double bonds were attached in polymers structure, making it suitable as a crosslinker. Reaction performances were evaluated through 1H NMR and FTIR. Then, p(NIPAM) microgels were prepared by emulsion polymerization using the crosslinker synthesized. The degree of substitution and the crosslinker concentration influence were verified and analyzed by SEM, DLS and UV-Vis with temperature control. The main observed changes were related to the phase transition temperature e microgels size. Using the crosslinker with higher substitution degree, it was possible the shift of the phase transition temperature to higher values (~35 °C). A mechanical response, observed trough microgels size, was found, driven by the crosslinker concentration and substitution degree. As higher the concentration and substitution degree of the crosslinker, higher was the swelling resistance observed in microgel structure.

Quand un liquide est refroidi suffisamment rapidement en dessous de sa température de solidification, il peut se former à la place du cristal un solide désordonné et hors équilibre appelé verre, après un ralentissement brutal de la dynamique du liquide. Cette transition vitreuse est très largement répandue, mais la cause du ralentissement reste pour une grande part mal comprise. Les suspensions colloïdales présentent une telle transition quand la fraction volumique en particules croît. Dans cette thèse, la dynamique de suspensions colloïdales de microgels thermosensibles est étudiée expérimentalement à l'approche de la transition vitreuse et au delà. Le diamètre de ces sphères molles dépend de la température du bain, ce qui permet de moduler de façon réversible la fraction volumique et d'étudier ainsi la transition vitreuse continument sur un seul et même échantillon. Dans un premier temps les hétérogénéités de la dynamique qui se développent simultanément au ralentissement de la dynamique, et jouent un rôle théorique majeur dans les tentatives d'explication de la transition vitreuse, sont étudiées en vidéo-microscopie. Sur des temps courts, une hétérogénéité purement spatiale de la dynamique est mise en évidence. Des zones lentes et rapides de dynamique homogène coexistent dans l'échantillon, l'amplitude des variations entre zones croissant à l'approche de la transition et restent grandes dans le verre. Dans un second temps, l'extension spatiale de ces zones homogènes est mesurée en corrélation d'image, et trouvée croissante à l'approche de la transition. Enfin, une méthode de mesure du mouvement brownien rotationnel en trois dimensions d'aiguilles micrométriques est développée et appliquée à la mesure des propriétés microrhéologiques de fluides complexes puis à la comparaison entre fluctuations et fonction de dissipation, mesurée grâce à la réponse des aiguilles superparamagnétiques à des champs magnétiques oscillants, dans des fluides modèles puis dans des suspensions vitreuses.

The adsorption and organization of reactive microgels has been investigated on technical aluminium. By means of a two-step emulsion polymerisation with phosphate substituted monomer we obtain polymeric nano-particles with phosphate groups on the surface. In a first step cross-linked butyl acrylate/styrene particles were formed. In a second step a mixture of functionalised acrylate and butyl acrylate/styrene was added to the system. In this way, the composite particles were obtained. Particle size and size distribution were measured by F-FFF and light scattering methods. For phosphate functionalised dispersions, it was possible to show the distribution of P-species around particles by energy dispersive TEM easurements. These nano-particles adsorb spontaneously onto aluminium surfaces from aqeous dispersion. They form well packed layers, which have been proved by SEM measurements. The properties of the adsorbed microgel layers were confirmed by industrial linked adhesion and corrosion tests. Panels with adsorbed phosphate funczionalised particles have an excellent corrosion inhibition effect.

This thesis describes the results of experimental work on polyelectrolyte gels and their interaction with oppositely charged surfactants, and presents two new algorithms applicable to the simulation of colloid and polymer systems. The model systems investigated were crosslinked poly(acrylate) (PA) and poly(styrene sulphonate) (PSS), and the surfactant was dodecyl trimethylammonium bromide (DoTAB). Pure gel materials were studied using dynamic light scattering. It was shown that the diffusion coefficient (D) increases with increasing degree of swelling and the concentration dependence is larger than predicted by scaling arguments. For gels at swelling equilibrium D increases with increasing degree of crosslinking. In subsequent studies on gel particles in DoTAB solution, Raman spectra were recorded at different positions in the gel. For both types of gels two distinct regions could be observed. For PA the surfactant is localised in the outer phase without any surfactant in the core, while for PSS the surfactant was distributed such that it had the same concentration relative to the polymer throughout the gel. In a second experiment, the kinetics for the deswelling of microscopic PSS particles in DoTAB solution was studied. It was found that the final volume varied linearly with the DoTAB concentration, and the rate of volume decrease could be fitted to a single exponential indicating stagnant layer diffusion to be the rate limiting process for the deswelling of the PSS particles. In the second part, I first describe an algorithm showing an efficient way to detect percolation in simulations, with periodic boundary conditions, using recursion. Spherical boundary conditions is an alternative to periodic boundary conditions for systems with long-range interactions. In the last part, the possibility to use the surface of a hypersphere in four dimensions for simulations of polymer systems is investigated, and algorithms for Monte Carlo and Brownian dynamics simulations are described.

The light scattering methods were used for characterization of properties and formation of networks of different dimension, based on N-vinylcaprolactam (VCL). Formation of PVCL microgels in presence of poly(vinyl alcohol) as stabilizer was studied. Size of resulting microgels strongly depends on the temperature and heating rate: interparticle aggregation was observed during slow heating and intraparticle collapse during fast heating. Angular dependence of measured diffusion coefficient on the angle of observation was studied for the microgel in the swollen, shrunken and aggregated states. Thermo-sensitive microgels based on N-vinylcaprolactam and acetoacetoxyethyl methacrylate were prepared under surfactant free conditions. The presence of internal part with low thermo-sensitivity and highly thermo-sensitive outer part of the particle (the core-shell structure of microgel) was deduced from static and dynamic light scattering experiments. Results obtained from combined SLS and DLS show the change of conformation from "swollen" soft sphere to compact shrunken "hard sphere". Thermo-sensitive microgel based on N-vinylcaprolactam and N-vinylpyrrolidone was used for investigation of the internal modes in microgel dispersion in the wide range of qRg values. Two internal motions and translation diffusion were observed in the asymptotic range. Angular dependence of the normalized diffusion coefficient showed power law behavior in this range. The experimentally determined value of exponent n = 0.96 was in good agreement with the value predicted for ZIMM limit for polymer chains with hydrodynamic interaction. The reduced first cumulant Ã*(q) reached a constant value in the range of large qRg values. Appearance of plateau value indicates ZIMM limit of hydrodynamic interaction but experimental value was much lower than the theoretically predicted plateau value for linear chains in good solution. 3,3?-(ethane-1,1-diyl)bis(1-vinyl-2-pyrrolidone) was used as a cross-linker of VCL in solution by radical polymerization. The network formation was investigated by dynamic light scattering. It was shown, that monitoring of the light scattered intensity in all cases is quite sensitive to detect the gelation threshold even in the presence of very low amount of cross-linker. The power law of time correlation function at the gel point is a sufficient but not a necessary condition for critical gelation. The exponent calculated from power law depends on cross-linker concentration and can be attributed to the degree of branching. Critical exponents obtained at the gel point by DLS and rheology for hydrogel system based on VCL and hydroxyethyl methacrylate were compared. The theoretically predicted equality of exponents from these methods was found as not valid at least for this studied system.

Esta tese apresenta os estudos realizados quanto à síntese e caracterização de microgéis termo-responsivos de N-isopropilacrilamida (NIPAM) e macromoléculas de origem amilácea em sua composição, sistemas ainda pouco explorados na literatura. Inicialmente, nanopartículas de amido (SNP) foram preparadas por nanoprecipitação para incorporação nos microgéis de interesse, através da dissolução dos grânulos do amido em DMSO/H2O, aplicação de ultrassom e precipitação em não-solvente. As SNPs preparadas foram utilizadas como copolímero para formação de microgéis híbridos do tipo SNP-co-p(NIPAM) através de polimerização em emulsão na presença e na ausência de surfactante. A influência das SNPs nas propriedades dos microgéis foi estudada por MEV, DLS, PZ e SAXS, onde foram observadas mudanças no comportamento físico-químico e estrutura supramolecular dos microgéis. No geral, observaram-se deslocamentos da temperatura de transição de fase para valores maiores (até 35 °C, cerca de 3 °C acima do valor determinado para sistemas contendo p(NIPAM) puro), aumento da estabilidade coloidal e organização dos polímeros presentes no microgel em uma arquitetura caroço-casca. As propriedades de inchamento dos microgéis também foram estudadas através da teoria de Flory-Rehner, onde a temperatura theta e o grau de polimerização entre dois pontos de reticulação foram determinados através do ajuste apropriado do parâmetro de interação (χ). Paralelamente, visando um sistema diferente do descrito acima, foi estudado um novo agente de reticulação baseado nos polímeros do amido, a amilose e a amilopectina. Para isso, os polímeros do amido que compõem as nanopartículas foram modificados para a utilização como agente de reticulação na síntese de microgéis de p(NIPAM). Nesta etapa, uma reação de substituição dos grupos hidroxila dos polímeros do amido foi realizada com o cloreto de acriloíla de forma a inserir insaturações na estrutura dos polímeros, para que estes fossem aplicados como reticulante. O sucesso da reação de modificação foi verificado através de RMN 1H e FTIR, no qual um maior grau de substituição foi obtido quando um tempo maior de reação foi empregado. Microgéis de p(NIPAM) foram então preparados através de polimerização em emulsão utilizando os reticulantes sintetizados. Observou-se a influência do grau de substituição e da concentração do reticulante nos microgéis, analisados por MEV, DLS e UV-Vis com controle de temperatura. As principais mudanças foram relativas à temperatura de transição de fase e tamanho dos microgéis. Utilizando o agente de reticulação com maior grau de substituição, foi possível deslocar a temperatura de transição de fase dos microgéis preparados para valores maiores (35 °C, cerca de 3 °C acima do valor determinado para sistemas contendo p(NIPAM) puro). Observou-se também uma resposta mecânica da rede do microgel, que refletiu no tamanho das partículas, influenciada pela concentração dos agentes de reticulação e do grau de substituição. Quanto maior a concentração e o grau de substituição do agente de reticulação, maior a resistência ao intumescimento observado no microgel. / This thesis presents the studies regarding the synthesis and characterization of thermoresponsive microgels of N-isopropylacrylamide (NIPAM) and amylaceous-based macromolecules, which are systems still little explored in the literature. At first, starch nanoparticles (SNP) were prepared by nanoprecipitation, through dissolution of starch granules in DMSO/H2O, ultrasound application and non-solvent precipitation. SNPs were then used as copolymer in SNP-co-p(NIPAM) hybrid microgels synthesized by emulsion polymerization in the presence and absence of surfactant. The influence of SNPs in microgel properties were studied by SEM, DLS, ZP, and SAXS, where changes in the physicalchemical behavior and supramolecular structure were observed. Summing up, shifts in the phase transition temperature up to 35 °C, increased colloidal stability, and microgel polymers organization into a core-shell structure were observed. Microgels swelling behaviour were also studied by the Flory-Rehner theory, where the theta-temperature and the degree of polymerization between two crosslinker points were determined through interaction parameter (χ) fitting. In parallel, a new starch-based crosslinker was studied. For this purpose, starch polymers (amylose and amylopectin within the SNPs) were modified in order to use them as crosslinker in p(NIPAM) microgel synthesis. In this step, a substitution reaction in hydroxyl groups of SNP was carried out with acryloyl chloride, where double bonds were attached in polymers structure, making it suitable as a crosslinker. Reaction performances were evaluated through 1H NMR and FTIR. Then, p(NIPAM) microgels were prepared by emulsion polymerization using the crosslinker synthesized. The degree of substitution and the crosslinker concentration influence were verified and analyzed by SEM, DLS and UV-Vis with temperature control. The main observed changes were related to the phase transition temperature e microgels size. Using the crosslinker with higher substitution degree, it was possible the shift of the phase transition temperature to higher values (~35 °C). A mechanical response, observed trough microgels size, was found, driven by the crosslinker concentration and substitution degree. As higher the concentration and substitution degree of the crosslinker, higher was the swelling resistance observed in microgel structure.