La variété des structures colloïdales auto assemblées est principalement due à la présence d'interactions anisotropes. Nous présentons ici une méthode numérique pour étudier l'agrégation irréversible par patches de particules sphériques. Il s'agit d'une amélioration de la dynamique d’amas browniens prenant en compte les interactions par patches et les mouvements de rotation. Nous limitons notre étude aux particules à deux patches opposés de taille variable. Une interaction isotrope, faible, est également ajoutée pour modéliser une polymérisation par étape dans diverses conditions de solvant. Cet algorithme a été testé sur des chaînes isolées et nous avons retrouvé les propriétés statiques et dynamiques attendues. En jouant sur la balance entre la qualité du solvant et la taille des patches diverses morphologies hors-équilibres sont obtenues. Même dans la limite diluée, les collisions corrélées jouent un rôle important et une description de type Smoluchowski échoue. / The versatility of self assembling structures is mostly due to the presence of anisotropic interactions. We present a new simulation method to study irreversible patchy aggregation of spherical particles. It is a variation of the Brownian Cluster Dynamics method taking into account patchy interactions and rotational motions. We limit our case to particles with two oppositely located patches. The size of patches can vary and an isotropic interaction is superimposed around the particle to mimic step-polymerization with various solvent qualities. This new algorithm was successfully tested on single polymer chains and expected static and dynamic properties were recovered. Depending on the balance between solvent quality and patch size various out of equilibrium morphologies could be obtained. Even in the limit dilute solutions, correlated collisions play a key role and the Smoluchowski approach fails. We propose new directions for a better understanding of anisotropy effects on kinetics.

A polymer is a large molecule constructed from many smaller structural units calledmonomers joined together by covalent bonds. Polymers have existed in natural formsince life began and those such as DNA, RNA, proteins and polysaccharides are someof the most important macromolecules found in plant and animal life. From the earliesttimes, the man has used many of these polymers as materials for providing clothing,decoration, tools, weapons and other requirements. However, the origins of today'spolymer industry commonly are accepted as being in the nineteenth century whenimportant discoveries were made concerning to the modification of certain naturalpolymers, as cellulose. The use of synthetic and natural polymers as stabilisers forcolloid systems (sols, dispersions, microemulsions, etc.) is becoming more importanteveryday in contemporary life. Polymer additives can be applied in preconcentrationsand dehydration of suspensions in mineral processing, purification of wastewater andeven in nutritional and pharmaceutical emulsions being their importance related to thecharacteristics of the process and the properties that they show. The present work aimsto develop appropriate numerical and analytical modelling techniques, which candescribe (considering the formation of loops and tails) the structure of a polymeric layeradsorbed on heterogeneous surfaces; this adsorbed layer is an relevant factor in theproperties showed by this kind of materials. Taking into account this, the methodologyknown as Single Chain Mean Field (SCMF) (originally used to study micellaraggregates and grafted polymers) was modified to apply on polymer adsorptionproblems. In this way, it was possible to calculate numerically properties that can beexperimentally measured, such as total monomer volume fraction profiles, loop and tailvolume fraction profiles, adsorbance or the thickness of the adsorbed layer. Thestructure of the polymeric layer was examined both for flat and spherical (colloidalparticles) surface geometries. When compared with other well establishedmethodologies for the numerical simulation of polymeric systems, this new version ofSCMF was found to be more efficient due to the improved sampling of the polymerchain configuration space.Thus, SCMF method results, in the case of the adsorption on flat surfaces, compare wellwith those obtained either with Monte Carlo simulations or with the method developedin the 80s by Scheutjens and Fleer (SCF). Due to the lack of studies focusing to polymeradsorption on colloidal particles, our results have been the first to present quantitativepredictions of the structure of the polymeric layer adsorbed on a spherical surface. Thus,we have demonstrated the dependence of the adsorbed polymer layer with the size ofthe colloidal particle as well as the characteristic lengths that influence on it. Finally, inthis work an analytical approach for the description of polymer-colloidal mixtures hasbeen developed which compares well with the numerical results obtained from theSCMF methodology. Furthermore, the analytical approach is able to predict systembehaviours, as for example the formation of gels. / Un polímero es una molécula de grandes dimensiones formada de pequeñas unidadesllamadas monómeros, los cuales se encuentran unidos por medio de enlaces covalentes.Los polímeros han existido de forma natural desde el comienzo de la vida, y aquelloscomo el DNA, RNA o las proteínas son algunos de los polímeros más importantesencontrados tanto en la vida animal como en la vegetal. Desde siempre el hombre hautilizado muchos de estos polímeros como materiales para hacer ropa, decoración,herramientas, etc. Sin embargo, el origen de la industria de polímeros que conocemoshoy en día se produjo en el siglo 19, gracias a importantes descubrimientos dentro de lamodificación de ciertos polímeros naturales, como la celulosa. El uso de polímerossintéticos y naturales como estabilizadores de sistemas coloidales (dispersiones,microemulsiones, etc.) juega en nuestros días un papel importante. Los polímerosutilizados como aditivos, pueden ser aplicados en preconcentraciones y deshidrataciónde suspensiones dentro de procesos minerales, tratamiento de aguas residuales e inclusolos podemos encontrar dentro de la industria farmacéutica y alimentaria, donde suimportancia es debida a la procesabilidad y propiedades que ellos exhiben. El trabajoque se presenta es orientado al desarrollo de técnicas de modelización, tanto analíticascomo computacionales, y su aplicación en la descripción (por medio de la formación debucles y colas) de la estructura de la capa de polímeros adsorbida en superficiesheterogéneas, siendo dicha capa de polímeros un factor importante en las propiedadesque este tipo de materiales presentan. Con este propósito, la metodología conocidacomo Single Chain Mean Field, utilizada anteriormente tanto para el estudio deagregados micelares como de polímeros anclados en superficies, ha sido modificadapara describir la adsorción de polímeros en superficies. Así se han podido calcularnuméricamente propiedades medibles experimentalmente como los perfiles de lafracción en volumen de monómeros totales, además de los pertenecientes a los bucles ycolas, adsorbancia o el espesor de la capa adsorbida, para geometrías de la superficieabsorbente tanto plana como esférica (partículas coloidales). En su comparación conotras metodologías, ya establecidas para la simulación numérica dentro de la física depolímeros, la aplicación de esta nueva versión del Single Chain Mean Field (SCMF)ha resultado ser más eficiente debido a un mejor muestreo del espacio deconfiguraciones de las cadenas poliméricas. De este modo, comparando los resultadosobtenidos a partir del SCMF, con aquellos obtenidos mediante técnicas de simulaciónMonte Carlo o la teoría desarrollada en los años 80 por Scheutjens y Fleer (SCF), se hapodido encontrar un buen acuerdo en las propiedades calculadas para el caso de laadsorción en superficies planas. Debido a la dificultad intrínseca del estudio de laadsorción en superficies curvadas, nuestros resultados son los primeros que presentanpredicciones cuantitativas sobre la estructura de la capa que se forma sobre unapartícula coloidal. Así hemos podido comprobar la dependencia de la estructura de lacapa de polímeros adsorbidos con el tamaño de la partícula sobre la que se encuentranadsorbidos además de las longitudes características de las cuales depende. Finalmente,en este trabajo se ha desarrollado, también, una teoría analítica para la descripción de lamezcla polímero-coloide. De este modo, los resultados numéricos obtenidos con elSCMF han podido ser comparados con dicha teoría, obteniendo, de nuevo, un buenacuerdo y predecir, además, comportamientos colectivos como la formación de geles.

The design of functional materials with complex properties is very important for different applications, such as coatings, microelectronics, biotechnologies and medicine. It is also crucial that such kinds of materials have a long service lifetime. Unfortunately, cracks or other types of damages may occur during everyday use and some parts of the material should be changed for the regeneration of the initial properties. One of the approaches to avoid the replacement is utilization of self-healing materials. The aim of this thesis was to design a self-repairable material with superhydrophobic and switchable properties using colloidal particles. Specific goals were the synthesis of colloidal particles and the preparation of functional surfaces incorporated with the obtained particles, which would exhibit a repairable switching behavior and repairable superhydrophobicity. In order to achieve these goals, first, methods of preparation of simple and functional colloidal particles were developed. Second, the behavior of particles at surfaces of easy fusible solid materials, namely, paraffin wax or perfluorodecane, was investigated.

Les procédés de séparation membranaire, utilisés couramment dans de nombreux domaines industriels, comme l’agro-alimentaire, le traitement des eaux ou les biotechnologies, sont de plus en plus mis en œuvre dans le domaine des bioraffineries. L’ultrafiltration tangentielle, par exemple, montre un fort potentiel dans l’étape de séparation des matières premières comme les nanocristaux de cellulose pour les transformer en biomasse. Cependant, l’augmentation de la concentration en particules à la surface de la membrane limite ce procédé, entrainant la formation des phénomènes de polarisation de concentration et de colmatage, réduisant les performances de filtration. Ces travaux de thèse ont pour objectif d’améliorer la compréhension des mécanismes de formation de ces phénomènes. Deux méthodes de caractérisation couvrant les échelles nanométriques à micrométiques ont été mises au point, grâce au développement de cellules de filtration couplant l’ultrafiltration à la diffusion de rayons X aux petits angles d’une part, et à la micro vélocimétrie par images de particules d’autre part. Ces mesures effectuées in-situ lors de la filtration tangentielle de suspensions de nanocristaux de cellulose et d’argile de Laponite, ont permis de caractériser l’organisation structurale et le champ hydrodynamique au sein des couches de polarisation. La corrélation de ces résultats avec les lois de comportement rhéologique des suspensions ont permis d’accéder pour la première fois aux champs de contraintes dans les couches de polarisation de concentration et de colmatage lors du procédé. / Membrane separation processes commonly used in several industrial applications, like bio and agro industries, waste water and clean water treatments, are more and more exploited in biorefinery. As an example, cross-flow ultrafiltration process shows a high potential in separation protocol of raw feed components like cellulose nanocrystals to produce biomass. This process is limited by the increase of particles concentration at the membrane surface, which conducts to phenomena named concentration polarization and fouling, which decrease the filtration performance. The PhD work objective is to bring a better understanding of the mechanisms involved in the formation of these phenomena. Two characterization methods covering length scales from nanometer to micrometer have been developed thanks to new designed tangential ultrafiltration cells allowing to link the ultrafiltration process to small angle X rays scattering and to micro particle image velocimetry. These measurement performed in-situ during ultrafiltration of nanocrystal celluloses and Laponite clay suspensions have allowed characterizing the structural organization and the velocity field within the concentration polarization layers. The correlation of these results with the rheological behavior properties of the suspensions, have permitted to access for the first time to the stress field within the concentration polarization and fouling layer during the tangential ultrafiltration process.

The design of functional materials with complex properties is very important for different applications, such as coatings, microelectronics, biotechnologies and medicine. It is also crucial that such kinds of materials have a long service lifetime. Unfortunately, cracks or other types of damages may occur during everyday use and some parts of the material should be changed for the regeneration of the initial properties. One of the approaches to avoid the replacement is utilization of self-healing materials. The aim of this thesis was to design a self-repairable material with superhydrophobic and switchable properties using colloidal particles. Specific goals were the synthesis of colloidal particles and the preparation of functional surfaces incorporated with the obtained particles, which would exhibit a repairable switching behavior and repairable superhydrophobicity. In order to achieve these goals, first, methods of preparation of simple and functional colloidal particles were developed. Second, the behavior of particles at surfaces of easy fusible solid materials, namely, paraffin wax or perfluorodecane, was investigated.

This study deals with the association of trace elements with colloids and particles in surface waters and groundwaters of mining and smelting district of Příbram. Colloids were studied using combination of cascade filtration a tangential flow ultrafiltration method to separate individual colloid fractions. Colloids were separated by filtration membranes with nominal pore size 0,8 μm, 0,45 μm, 0,1 μm, 100 kDa, and 5 kDa. Water samples were analyzed using ICP-OES, ICP-MS and HPLC. The data were used for thermodynamic modeling using PHREEQC-2 programme. The results show that major and trace elements can be divided into several groups, based on their abundance in individual size fractions. Most elements dominate in fraction of truly dissolved matter as dissociated ions (< 5 kDa), maximum concentration in colloid fraction is 5-20 % and almost exclusively in fraction 5 kDa - 100 kDa. Gradual decrease of concentration in all fractions at low ionic strength (1,2 mmol/l) was observed in case of elements such as As, Co, Cr, Si, Sb and U. Gradual decrease of concentration in several samples was observed for Cd, Fe, Pb, Mn and Zn. Dominant binding to colloids and particles in surface waters was observed for Fe and Pb, where these fractions accounted for over 90 %. The main factor influencing colloid...

Nous proposons dans cette thèse une étude sur la stabilisation de bulles de gaz dispersées en solution aqueuse par des nanocapsules lipidiques (NCL). L’objectif est le développement d’un système de libération d’actifs pharmaceutiques provoquée par l’application d’un champ ultrasonore adéquat. Préalablement, est évaluée la potentialité des NCL à se comporter comme de vrais agents de stabilisation interfaciale air/eau. Les NCL sont capables de diminuer la tension de surface plus que le Solutol®, principal surfactif pégylé rentrant dans leur composition.La méthode d’agitation mécanique s’est révélée la mieux adaptée pour formuler des microbulles d’air stabilisées.Les microbulles générées ont une taille moyenne inférieure à 2μm avec une concentration de 2,72.1012/mL. La distribution de taille est assez homogène avec un indice de polydispersité acceptable. Le ratio d’incorporation d’air dans les bulles est de 0,17. Les microbulles sont entourées d’un film constitué principalement de Solutol® et de Lipoïd®. En dispersion aqueuse, la stabilité des bulles à température ambiante(20°C±2°C) est maintenue jusqu’à 7 jours au moins. Le fusidate sodique utilisé comme actif pharmaceutique modèle et comme traceur est encapsulé avec un taux de27-35%. Un taux de libération de 40-50% est obtenu dans des conditions normales de libération. Ce pourcentage atteint 50-55% après application d’ultrasons. / This work deals with the stabilization of gaz microbubbles dispersed in aqueous solutions by using LipidNanoCapsules (LNC). The main objective is the development of a Drug Delivery System where the release is triggered by ultrasonation. Firstly, we investigated the ability of LNC to behave as real air/water interfacial stabilization agents. It is shown that LNC can decrease the surface tension at the air/water interface more than the Solutol®, main pegylated surfactant of the LNC. Usual stirring method seems the more efficient to produce stabilized air microbubbles. Microbubbles are characterized by a mean size below 2μm and are concentrated at 2.72x1012 /mL. The size distribution ishomogeneous with a convenient polydispersity index.The gas holdup inherent to the microbubbles was estimated to 0.17. Microbubbles are surrounded by a film constituted by Solutol® and Lipoïd®. Their stability at room temperature was kept up to 7 days. Sodium Fusidate was chosen as a drug model with an encapsulation rate in a 27-35% range. The drug release upon ultrasound was between 50-55 % in comparison with 40-50 % without ultrasounds focusing.

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