The goal of this work was to quantify the mechanical properties of cellulose nanocrystal (CNC)-based thin films using a polystyrene (PS) structuring approach. This structuring approach was used to biaxially wrinkle CNC-polymer and all-CNC films, in order to assess how changes in the film fabrication process affected the elastic modulus of these films. All films were prepared on pre-stressed PS substrates and structured by heating them above the glass transition temperature of PS, which caused the substrates to shrink and the films to wrinkle biaxially. CNC-polymer films were prepared using the layer-by-layer approach, where three parameters were modified to obtain films of varying compositions: 1) type of polymer (xyloglucan, XG, or polyethyleneimine, PEI), 2) polymer concentration (0.1 wt% or 1 wt%), and 3) film thickness (i.e., number of deposited bilayers). After these films were structured, their elastic moduli were calculated to be 70 ± 2 GPa for CNC-XG0.1, 72 ± 2 GPa for CNC-PEI0.1, and 32.2 ± 0.8 GPa for CNC-PEI1.0 films, indicating that the mechanical properties of CNC-polymer films changed with film composition. This structuring method was also found to provide a humidity-independent measurement of the modulus due to the irreversible nature of the wrinkling. Next, to prepare all-CNC films, CNC suspensions were evaporated under conditions designed to control the film thickness (using 0.005 wt% – 8 wt% CNC suspensions) and CNC nanoparticle orientation (chiral nematic, isotropic, or uniaxial). Suspensions were dried slowly under vacuum, quickly by heating, or by spin-coating to form films with chiral nematic, isotropic, or uniaxial (radial) CNC orientations, respectively. Following structuring, these wrinkled films showed unique morphologies that changed with nanoparticle orientation, suggesting that their mechanical properties are dependent on the CNC orientation within the films. The work presented in this thesis implies that the mechanical properties of films fabricated from hygroscopic bio-based nanomaterials can be assessed in a humidity-independent way by using the structuring method presented. Quantifying the mechanical properties of these films is critical to assess the potential applications of CNCs, where CNC-based materials may be used in developing paper-based electronics, extracellular matrix mimics, and plant cell wall mimics. / Thesis / Master of Science (MSc)

Group 3 and 4 complexes bearing linked cyclopentadienyl amido ligands, often referred to as constrained geometry complexes (CGCs), have experienced considerable interest due to their superior ability to copolymerise ethylene and higher alpha-olefins when activated with suitable co-catalyst.The work presented in this thesis aimed to replace the most commonly applied bridge in CGCs, which is silicon based, by one containing boron. The potential of the bridging element to have Lewis acidic character was expected to positively alter the catalytic activity of the activated species and possibly allowing for self-activation.Synthetic approaches to ligand precursors based on aminoboranes, diaminodiboranes(4) and ferrocenylboranes are described. Starting from the dihalo derivatives of these boranes, sequential substitution of the halides by one equivalent each of a cyclopentadienide derivative and an amide allowed the synthesis and isolation of a broad range of new CGC ligand precursors.Complexation of these ligand precursors to Group 4 metals was studied by utilising various protocols. The reaction with Group 4 tetraamides via amine elimination was the most successful yielding numerous new boron-bridged CGCs and related complexes in which the boron-bridged ligand binds in a non-chelating fashion.The newly synthesised compounds were fully characterised by multinuclear NMR spectroscopy, supplemented by X-ray diffraction studies where applicable.Studies on the reactivity of boron-bridged CGCs in the presence of alkylating agents indicated susceptibility of the boron atom to nucleophilic attack resulting in a decomposition of the linking moiety between the cyclopentadienyl and amido fragments. This is as well reflected in the data gathered from polymerisation experiments, in which methylaluminoxane activated boron-bridged CGCs displayed a low activity towards ethylene polymerisation, but a high activity towards styrene polymerisation. Such characteristics are comparable to unbridged compounds, e.g. [(eta5-C5H5)TiCl3], rather than silicon-bridged CGCs, thus suggesting degradation of the boron-bridged CGCs to unbridged complexes under polymerisation conditions.

L‟objectif de cette thèse est de valoriser les polymères styréniques issus des déchets d‟équipements électroniques et électriques. Les polymères considérés sont le polystyrène (PS), le polystyrène choc (HIPS), le poly(acrylonitrile-butadiène-styrène) (ABS), l'ABS couplé avec du polycarbonate (ABS/PC) et le poly(styrène-acrylonitrile) (SAN). Une étude préliminaire a permis de définir deux mélanges à compatibiliser : le mélange PS/ABS et le mélange PS/PC. Pour le mélange PS/ABS, la voie de compatibilisation ionique est étudiée. L‟ajout d‟un copolymère présentant une structure ionique et la création d‟un réseau in-situ sont tentés. Ces deux voies n‟ont pas donné de résultats concluants en termes d‟amélioration des propriétés finales du mélange. Le mélange PS/PC est lui compatibilisé par ajout d‟un copolymère polystyrène bloc-poly(éthylène-butylène)-bloc-polystyrène greffé PC. Ce copolymère est tout d‟abord créé en mélangeur interne, afin d‟étudier différents catalyseurs susceptibles d‟initier le greffage, puis l‟extrusion réactive est utilisée pour synthétiser ce copolymère à grande échelle. Plusieurs taux de copolymère sont alors introduits dans le mélange PS/PC et l‟amélioration des propriétés et des microstructures prouve son effet compatibilisant / The aim of this work consists in the recycling of the styrenic polymers coming from waste of electric and electronic equipments. Polystyrene (PS), high impact polystyrene (HIPS), poly(acrylonitrile-butadiene-styrene) (ABS), its alloy with the polycarbonate (ABS/PC) and poly(styrene-acrylonitrile) (SAN) are considered. A preliminary study permits to choose two blends to study: PS/ABS and PS/PC. In the case of PS/ABS blend, the ionic way of compatibilization was studied. The addition of a copolymer containing an ionic structure and the creation of an ionic network in-situ are investigated. Both these attempts are not conclusive about the improvement of the final properties of the blend. The PS/PC blend is then compatibilized by adding a polystyrene-block-poly(ethylene-butylene)-block-polystyrene grafted polycarbonate. This copolymer is first created in an internal mixer, in order to study different catalysts able to initiate the grafting, and then the reactive extrusion is used to synthesize it on a large scale. Several amounts are introduced in the PS/PC blend and the improvement of the properties and microstructures proves its compatibilizing effect

O bagaço de cana-de-açúcar é um abundante coproduto obtido a partir da produção convencional de etanol. No entanto, o bagaço vem se mostrando como uma importante fonte para a produção de etanol de segunda geração. No primeiro capítulo da tese é apresentado um estudo referente à distribuição espacial dos compostos na matriz de bagaço de cana-de-açúcar. A investigação foi realizada utilizando microscopia de fluorescência confocal e espectroscopia por excitação com um e dois fótons. Imagens de autofluorescência em combinação com as medidas de fluorescência e tempos de vida forneceram uma gama de informações necessárias para a caracterização de amostras de bagaço. Além disso, a técnica permite o acompanhamento de processos relacionados com a remoção de lignina. A nanocelulose cristalina (NCC) é um material promissor devido as suas propriedades intrínsecas, tais como seu formato alongado, medindo de 1 a 100 nm de diâmetro e seu comprimento variando de algumas dezenas a centenas de nanômetros. No capítulo 2, a nanocelulose cristalina foi obtida através da hidrólise da celulose cristalina (de Avicel®) com ácido sulfúrico. Em seguida, o material foi caracterizado por técnicas de microscopia SEM e TEM, confirmando a morfologia em forma de haste e a estrutura de tamanho nanométrico. A microscopia de campo largo convencional foi utilizada como ferramenta na caracterização da NCC dispersa em soluções poliméricas de PVA e PVP. A última parte do capítulo 2 descreve a caracterização de estruturas de NCC usando a microscopia de super-resolução de fluorescência STED (depleção de emissão estimulada). As imagens mostraram uma resolução de até 50 nm, permitindo a comparação com resultados de TEM e AFM. No capítulo 3, a nanocelulose cristalina foi covalentemente marcada com o corante ATTO-532, através da chamada reação \"click\". As propriedades relacionadas com o coeficiente de difusão da NCC foram determinadas por espectroscopia de correlação de fluorescência (FCS). Em uma etapa posterior, a NCC foi colocada em diferentes soluções do polímero PEG, contendo quantidades diferentes. As propriedades dinâmicas foram analisadas por métodos de FCS e WFM. O uso de técnicas de espectroscopia e microscopia revelou detalhes relacionados à heterogeneidade das dispersões de NCC, as quais estão relacionadas com as propriedades hidrofílicas e hidrofóbicas das soluções poliméricas. / The sugarcane bagasse is an abundant co-product obtained from the conventional production of ethanol. However, sugarcane bagasse has been proving to be an important source to the production of second-generation ethanol. In the first chapter, the spatial distribution of compounds in the sugarcane bagasse matrix was investigated by confocal fluorescence microscopy and spectroscopy with one and two-photon excitation. Autofluorescence images in combination to spectral emission and lifetime measurements provided a tool for the characterization of natural bagasse samples. Moreover, the technique allows the following of processes related to the lignin removal. Nanocrystalline cellulose (NCC) is a promisor material because of its properties, such as rod-shape with 1-100 nm in diameter, and tens to hundreds of nanometres in length. In the Chapter 2, NCC was obtained via sulphuric acid hydrolysis from Avicel®. Afterwards, the material was characterized by classic electronic microscopy SEM and TEM, confirming the rod-shaped morphology and the nano-sized structure. Conventional wide field microscopy was used as fluorescence microscopy tool in the characterization of NCC, when dispersed in polymeric solutions of PVA and PVP. The last part of the chapter 2 describes the characterization of NCC structures by using the super-resolution fluorescence microscopy STED (Stimulated Emission Depletion). The STED images showed a resolution down to 50 nm, allowing the comparison with TEM and AFM microscopy results. In the Chapter 3, the NCC was covalently labelled, by a click-chemistry reaction, with the ATTO-532 dye. Properties related to diffusion coefficient of NCC were determined by Fluorescence Correlation Spectroscopy (FCS) method. Afterwards, NCC was placed into a solution of PEG, containing different amounts polymer. The dynamic properties were evaluated by FCS and WFM methods. The use of spectroscopy and microscopy imaging techniques revealed heterogeneity details of NCC dispersions, which are related to the hydrophilic and hydrophobic properties of the polymer solution. A better understanding of polymer systems is achieved by investigation of diffusion properties, that allows the comprehension of rheological parameters, and, consequently, in polymer processing and assembly of plastics, films, and fibres. In the Chapter 4 is presented a study where fluorescence correlation spectroscopy (FCS) and wide-field fluorescence microscopy (WFM) were used to follow changes in the diffusion coefficients of growing polymer chains, during the controlled radical polymerization process. Linear and star-shaped polystyrene were grown via nitroxide-mediated polymerization (NMP) from alkoxyamine-based initiators containing a highly fluorescent perylene diimide moiety. This study demonstrates that direct investigation of heterogeneity emerging during a controlled radical polymerization process by means of fluorescence of single-molecule chain initiator allows unravelling information related to the diffusion processes of the growing polymer chain.

O objetivo do trabalho foi sintetizar e caracterizar nanopartículas de poliestireno e polimetacrilato de metila com morfologia núcleo-casca obtidas através da polimerização em emulsão sem emulsificante em dois estágios e através da fotopolimerização. Nos experimentos avaliou-se a influência de diferentes condições operacionais baseadas em fatores cinéticos sobre os dois estágios da polimerização. As condições avaliadas para o primeiro estágio de preparação de núcleos foram: a temperatura do processo, a concentração de iniciador e de monômero, e o efeito de agentes modificadores de superfície (sal, co-monômero e reticulante). Para o segundo estágio de formação da casca as condições avaliadas foram: a concentração e o regime de alimentação de monômero. Os resultados experimentais mostraram que uma relação de co-monômero e reticulante é a melhor alternativa para preparar núcleos estáveis e de diâmetros pequenos. Assim, o revestimento uniforme dos núcleos é obtido no segundo estágio e com isso a morfologia núcleo-casca em equilíbrio é alcançada. Dois sistemas experimentais (reator convencional e reator fotoquímico) foram propostos e avaliados na sua eficiência para obter partículas com este tipo de morfologia no segundo estágio (formação do revestimento). As diversas técnicas de caracterização indicaram a formação de morfologia núcleo-casca na maioria dos casos estudados para os dois sistemas propostos. Por sua vez, as técnicas espectroscópicas (NIR e Raman) permitiram o monitoramento do processo em tempo real e a elaboração de modelos de calibração que correlacionaram o crescimento do tamanho da partícula núcleo. Da mesma forma, os fatores termodinâmicos foram estudados para predizer a morfologia final esperada nos sistemas. Os resultados, experimental e predito são comparados e discutidos em termos de aspectos chave envolvidos no controle da morfologia da partícula. / This work aimed at studying the synthesis and characterization of core-shell nanoparticles of polystyrene and polymethylmethacrylate obtained in a two-stage emulsifier-free emulsion polymerization and photopolymerization. The influence of different operational conditions based on kinetic factors was experimentally evaluated. In the first stage (seed preparation) the process temperature, initiator and monomer concentrations and the effect of surface-modifier agents (acids, salts, co-monomers and crosslinker) were investigated; similarly in the second stage, the concentration and feeding regime of monomer were evaluated with respect to the shell formation. Experimental results showed that both, crosslinker and co-monomer are the best alternative to achieve a stable seed with small diameter; hence, with this core, uniform coating is obtained in the second stage and core-shell morphology is reached. In order to evaluate the efficiency of the preparation of core-shell particles, two experimental systems (conventional and photochemical reactor) were studied. Different characterization techniques indicated that in most of the cases studied particles with the desired core-shell morphology were formed. The use of spectroscopic techniques NIR and Raman were tested for the real-time monitoring of the process using adequate calibration models developed to correlate the average size of the growing core particle with the spectra. In the same way, thermodynamic factors were used to predict the expected final morphology of the particles. Experimental and predicted results were compared and discussed in terms of the key aspects involved in the control of the particle morphology.

O presente projeto tem como objetivo contribuir para o desenvolvimento de dispositivos para monitoração de pressão dinâmica do ar. Para isso, foram produzidos filmes sensíveis a pressão baseados na detecção de concentração de oxigênio por meio de processos de emissão fotoluminescente das moléculas de Azul de Metileno (MB) e Platina Octaetilporfirina (PtOEP). Nesse sentido, foi estudado o comportamento da emissão fotoluminescente dessas moléculas em interação com o gás de oxigênio. A concentração de oxigênio (do ar) sobre superfície sensível depende da pressão dinâmica de superfície. Desta forma, monitorando a fotoluminescência dos dispositivos submetidos a diferentes concentrações de oxigênio, pode-se determinar uma relação entre a pressão pontual da superfície analisada e a intensidade de emissão fotoluminescente do filme. Os dispositivos de monitoração de pressão dinâmica são constituídos de um filme de estado sólido contendo as moléculas sensíveis. Foram utilizados como substratos hospedeiros para o Azul de Metileno e para a Octaetilporfirina de Platina, os filmes de silício poroso oxidado e Poliestireno, respectivamente. É proposto um arranjo experimental que utiliza um fluorímetro para caracterizar as amostras produzidas e uma câmara de fluxo de gases. Os dispositivos apresentaram elevada sensibilidade e evidenciaram o potencial para desenvolvimento e integração de sensores baseados no silício poroso à microeletrônica. / This project aims to contribute to the development of devices for monitoring dynamic pressure of the air. In this sense, films were produced based on pressure-sensitive detection of oxygen concentration through processes of photoluminescence emission from the molecules of methylene blue (MB) and platinum octaethylporphyrin (PtOEP). Accordingly, it was studied the behavior of the photoluminescence emission of these molecules in interaction with the oxygen gas. The concentration of oxygen (of the air composition) on the sensitive surface depends on the surface dynamic pressure. Thus, monitoring the photoluminescence of the devices under different oxygen concentrations, it can be determined a relationship between the punctual pressure of the tested surface and the photoluminescence emission intensity of the film. The devices for monitoring dynamic pressure are made of a solid state film containing the sensitive molecules. Oxidized porous silicon and polystyrene films were used as hosts for the Methylene Blue and for the Platinum Octaethylporphyrin, respectively. It was proposed an experimental setup that uses a spectrofluorophotometer and a gas flow chamber to characterize the produced samples. The devices showed high sensitivity and potential for development and integration of the sensors based on porous silicon for microelectronics.

Ce travail concerne l’altération du comportement de phase de membranes lipidiques lors de leur interaction avec des molécules hydrophiles ou hydrophobes. L’utilisation de sondes moléculaires de fluorescence sensibles à leur micro-environnement constitue un aspect majeur de ce travail. Les techniques de spectroscopie de fluorescence et de microscopie confocale ont été mises à profit pour l’étude du comportement de ces sondes, donnant accès au degré de compacité et d’ordre dans les membranes.Nos résultats montrent que le polystyrène, un plastique rencontré de façon commune dans les régions polluées des océans, présente la capacité de modifier le comportement de phase des membranes lipidiques, entrant notamment en compétition avec le cholestérol.Nous avons montré que la présence élevée de sucres, tel que l’on peut le rencontrer dans certaines situations relevant de la bio-préservation, a pour effet de rompre la qualité de compaction des lipides, et nous avons proposé un nouveau modèle thermodynamique pour interpréter nos résultats.Enfin, les effets sur la membrane de l’incorporation d’un polymère amphiphile comportant un cholestérol greffé ont été étudiés, dans le cadre de l’élaboration de nouvelles stratégies thérapeutiques à base de lipides. / This work focuses on the alterations of lipid membrane phase behavior upon interaction with hydrophobic and hydophilic molecules. One major aspect of this thesis is the employement of environment sensitive probes to obtain information on the lipid bilayer packing by means of confocal spectral imaging and fluorescence spectroscopy. Our results show that polystyrene, a commonly found plastic in ocean wastes, has the ability to disrupt the lipid bilayer phase behavior and has a competitive interaction with cholesterol. The presence of high concentration of sugars, relevant in the field of biopreservation, has been found to alter the lipid bilayer packing and a new thermodynamics model has been proposed to complement the experimental results. Finally, the effects of an amphiphilic cholesterol-grafted polymer on model membrane was investigated, providing insight into potential new lipid therapeutic strategies.

Dans le cadre des procédés de clarification d'eau de surface, les flocs formés au cours des étapes de coagulation et de floculation peuvent être séparés de l'eau traitée par décantation ou par flottation. Dans ce dernier cas, le procédé actuellement en vigueur est la flottation à air dissous et présente un certain nombre d'inconvénients. Ainsi, dans ce contexte, la présente thèse consiste à développer un matériau innovant, à la fois flottant et floculant, pour une application dans un procédé de flottation sans air. Dans un premier temps, l'élaboration de billes de polystyrène expansibles utilisant l'eau ou l'éthanol comme agent gonflant a été réalisée. D'autres billes ont ensuite été préparées en présence de 4-(chlorométhyl)styrène comme co-monomère puis la polymérisation par transfert d'atome amorcée en surface (SI-ATRP) de l'acrylamide a été effectuée avec succès. L'impossibilité d'expanser ces matériaux a ensuite conduit à l'exploration de nouvelles voies de synthèse avec la fonctionnalisation de matériaux flottants existants par des techniques de « grafting from » ou « grafting onto ». Quelle que soit la voie envisagée, la première étape a consisté à réduire les fonctions nitrile en amine primaire en présence d'hydrure d'aluminium lithium. Après fonctionnalisation par du bromure de bromoisobutyryle ou du chlorure d'acryloyle, il a été possible de venir greffer de l'acrylamide par SI-ATRP ou de l'amidon via un amorceur redox, respectivement. Les matériaux flottants/floculants obtenus ont été testés lors de flottatests. Les meilleurs résultats ont été obtenus avec les microsphères fonctionnalisées par de l'amidon anionique. Ces dernières ont permis d'abattre la turbidité de l'eau, ont ensuite été régénérées avec succès, par des bains d'acide oxalique ou de dithionite de sodium, et employées durant plusieurs cycles flottatest/régénération avec des résultats reproductibles. / At the end of clarification process, after coagulation-flocculation steps, flocs can be removed from treated water by settling or flotation. In the latter case, Dissolved Air Flotation is the currently used process. However, this method showed important drawbacks, especially an important energetic cost due to the production of air saturated water. In that context, the goal of the reported work dealt with achieving air-free flotation using innovative floating materials. First of all, the synthesis of expandable polystyrene beads using water or ethanol as blowing agent was investigated. Other beads containing both styrene and 4-(chloromethyl)styrene were prepared. Then, surface initiated atom transfer radical polymerization of acrylamide (SI-ATRP) was achieved. Unfortunately, the expansion of such materials was not possible. Therefore, the second part focused on the functionalization of Expancel beads by “grafting from” or “grafting onto” techniques. The first step consisted in reducing some nitrile functions at the surface into primary amine ones. After functionalization with bromoisobutyryl bromide, the SI-ATRP of acrylamide was performed in water at room temperature. On the other hand, the acryloyl chloride was grafted onto amine functions, and grafting of starch was achieved using a redox initiator. All materials obtained have been used for flocculation/flotation tests and demonstrated satisfactory performances in terms of turbidity removal. Beads functionalized with starch have been successfully regenerated with oxalic acid and sodium dithionite and kept appropriate efficiency during several flotation/regeneration cycles.

Philosophiae Doctor - PhD / Polyaniline nanocomposites doped with poly(vinylsulphonate) (PV-SO3) and nanostructured polystyrene (PSNP) latex beads functionalized with amine (PSNP-NH2) and sulphate ((PSNP-OSO3) were prepared and characterised for use as nitrite electro-catalytic chemosensors and ochratoxin A immunosensors. The resultant polyaniline electrocatalytic chemosensors (PANI, PANI|PSNP-NH2 or PANI|PSNP-OSO3 −) were characterized by cyclic voltammetry (CV), ultraviolet-visible (UV-Vis) spectroscopy and scanning electron microscopy (SEM). Brown-Anson analysis of the multi-scan rate CV responses of the various PANI films gave surface concentrations in the order of 10−8 mol/cm. UV-vis spectra of the PANI films dissolved in dimethyl sulphoxide showed typical strong absorbance maxima at 480 and 740 nm associated with benzenoid p-p* transition and quinoid excitons of polyaniline, respectively. The SEM images of the PANI nanocomposite films showed cauliflower-like structures that were <100 nm in diameter. When applied as electrochemical nitrite sensors, sensitivity values of 60, 40 and 30 μA/mM with corresponding limits of detection of 7.4, 9.2 and 38.2 μM NO2 −, were obtained for electrodes, PANI|PSNP-NH2, PANI and PANI|PSNP-SO3 −; respectively. Immobilisation of ochratoxin A antibody onto PANI|PSNP-NH2, PANI and PANI|PSNPSO3 - resulted in the fabrication of immunosensors. / South Africa

Cette étude porte sur l’assemblage de particules à patchs pour obtenir de nouveaux matériaux. L’étatde l’art a permis de choisir et de mettre en oeuvre une stratégie originale dont la force motrice est l’assemblageinduit en milieu solvant, c’est-à-dire basé sur le caractère collant des macromolécules de polystyrène (PS)lorsqu’elles sont soumises à un mélange d’un bon et d’un mauvais solvant. Nous avons étudié l’assemblage enclusters, en chaînes ou en monocouches de nanoparticules (NPs) de silice possédant respectivement un, deux outrois patchs, constitués de macromolécules de PS greffées à des endroits spécifiques de leur surface. Les NPs desilice à un patch, présentant un rapport de taille patch/particule contrôlable, ont été synthétisées avec succès parune étape de séparation de phases induit par gonflement suivie d’un dépôt de silice régiosélectif. Leur assemblagea été réalisé dans des mélanges binaires DMF/éthanol. Les effets de la qualité du solvant, de la force decentrifugation, de la concentration en NPs, de la durée d'incubation et du rapport de taille patch/particule ont étéétudiés et discutés. La stratégie a été étendue pour obtenir des clusters à base d’or. Les NPs de silice à deuxpatchs ont été préparées par un procédé de polymérisation en émulsion ensemencée du styrène et le rapport detaille patch/particule a été ajusté via le taux de recroissance du noyau de silice. L’assemblage en chaînes des NPsa été réalisé dans des mélanges THF/solution aqueuse de NaCl en faisant varier la concentration en NaCl, lerapport volumique THF/eau, la durée d’incubation, la concentration en NPs et le rapport de tailles patch/particule.Nous avons montré que la cinétique de croissance des chaînes est typique d’une croissance par étapes. Desstratégies pour imiter des homopolymères, des copolymères statistiques, des copolymères séquencés à blocs etdes polymères ramifiés ont été mises en oeuvre, en utilisant comme briques de base des NPs à un patch, des NPsà deux patchs avec des tailles ou des fonctions de surface différentes et/ou des NPs à trois patchs. Les NPs desilice à trois patchs ont été obtenues par la même voie de synthèse que celles à deux patchs. Pour les assemblerdans des structures 2-D en nid d'abeille, nous avons utilisé la technique de Langmuir et nous avons étudiél'influence de différents paramètres expérimentaux. Une étape de recuit sous vapeur de THF a été mise en oeuvre,ce qui a permis de renforcer mécaniquement l’assemblage, mais sans effet significatif sur la compacité. / This study deals with the assembly of patchy particles to get new materials. The state-of-the-art allowedus to select and implement an original strategy whose driving force is the solvent-induced assembly, i.e. based onthe stickiness of polystyrene (PS) macromolecules when they are subjected to a mixture of good and bad solvents.We investigated the assembly into clusters, chains or monolayers of one-patch, two-patch or three-patch silicananoparticles (NPs), respectively, the patches being PS macromolecules grafted at specific positions on theirsurface. One-patch silica NPs with controllable patch-to-particle size ratio were successfully synthesised throughphase separation and site-specific silica coating. Their assembly was performed in DMF/ethanol binary mixtures.The effect of the solvent quality, centrifugation force, particle concentration, incubation time and patch-to-size ratiowas investigated and discussed. The strategy was spread to obtain gold-coated clusters. The two-patch silica NPswere prepared through a seed-growth emulsion polymerisation of styrene and the patch-to-particle size ratio wasadjusted through the extent of the silica core regrowth. The chaining of the NPs was efficiently achieved in theTHF/NaCl aqueous solution mixtures by varying the NaCl concentration, solvent quality, incubation time, NPsconcentration and patch-to-particle size ratio. We showed that the kinetics of the chaining process is characteristicof a reaction-controlled step-growth polymerisation. Strategies to mimic homopolymers, random copolymers, blockcopolymers and branched polymers were implemented by using one-patch NPs, two-patch NPs with different sizes/surface chemical functions and/or three-patch NPs as building units. The three-patch silica NPs were obtainedthrough the same synthetic pathway than two-patch ones. For assembling them in honeycomb-like 2-D structures,we used the Langmuir technique.and we studied the influence of different experimental parameters. THF vapourannealing was implemented to reinforce mechanically the assembly but without significative effect on the packingdensity.