Aluminosilicate inorganic polymers (AIPs) are network heteropolymers consisting of Si04 and AlO4 tetrahedra linked by a shared oxygen. The use of these materials as a cementing agent, toxic waste storage and fibre reinforced material, amongst a multitude of prospective applications, has grown in recent years. The utilisation of AIPs is hampered by a lack of knowledge about their formation and structure. In order to allow the materials to achieve their full potential, the way in which the material behaves and forms under different conditions must be elucidated. The basic questions that this study aimed to answer were: 1) How does the structure of these AIPs change with composition? and 2) Can this change in structure explain the material properties of the AIP? The AIPs investigated in the study covered the molar composition ranges Si:Al ratio = 1 - 3 and Na:Al ratio = 0.5 - 2. They were made by the sodium hydroxide activation of metakaolinite, derived from the dehydroxylation of kaolinite. The Si content of the AIP was altered by the addition of amorphous silica fume via the activation solution. The study considered the structural nature of the AIPs at the macro, micro and nanoscales, and found that the structure changed at all scales and with all compositions. The nature of the AIP structure was studied at the macroscale utilising compressive strength testing. The results from this work showed that the compressive strength of the AIPs varied systematically with the chemical composition. The strengths recorded ranged from 0.4 ± 0.2 MPa for a sample with Si:Al:Na molar ratios = 1.08:1:0.5, to 64 ± 3 MPa for a sample with Si:Al:Na molar ratios = 2.5:1:1.3. The higher strengths measured exceed those exhibited by Portland cement pastes. The microstructure of the AIPs was investigated by scanning electron microscopy and energy dispersive spectroscopy. / Microscopy showed that the microstructure variations correlated with the compressive strength. In general, AIPs with low compressive strengths exhibited an inhomogeneous two-phase microstructure; grain and matrix. The grain phase consisted of undissolved metakaolinite, whilst the matrix was the fully formed inorganic polymer. AIPs with high compressive strengths exhibited a microstructure that was more homogeneous than the samples with low compressive strength. The compressive strength of the AIPs depended on both the chemical composition and the level of residual MK present in the microstructure. EDS microanalysis showed that the composition of the two phases was significantly different, and that the differences depended on the overall composition of the AIP. EDS results also demonstrated that the impurity elements present in the metakaolinite were affected by the polymerisation process. Soluble elements such as Ca and Mg were found primarily in the matrix, indicating that they had leached out of the metakaolinite grains, whereas insoluble elements such as Fe and Ti were found primarily in the grains. The nanoscale structure of the AIPs was examined by solid-state nuclear magnetic resonance (NMR) and x-ray scattering (XRS). The NMR measurements revealed that the average coordination of Si varied according to the composition of the AIP, whereas the coordination of Al was constant. Na is present in the network in both hydrated and non-hydrated forms. It is postulated that the variation in the Si coordination can be explained by the formation of Si-O-Na bonds with Na forming an ionic bond with 0 in the polymer network. Radial distribution function (RDF) analysis of the XRS patterns revealed little difference in the structure of the different AIPs beyond ~2.5 Å. / Unfortunately, the data were of insufficient resolution to allow for a full evaluation of the differences in the Si-O and Al-O bonds between different AIPs. However, the trends present in the shape and position of the RDF peak corresponding to the Si-O and Al-O bonds do follow the composition of the AIP. It has been shown that a variety of experimental techniques can be used in concert to obtain information on the structural nature of AIPs. To this end, it has been found that the compressive strength of AIPs can be optimised, and that the microstructure of the AIPs changes systematically with variations in the compressive strength. An improved model for the structure of AIPs has also been proposed.

Soil stabilization is a widely used technique in the field of geotechnical engineering for a wide range of applications. Traditional stabilizers such as cement and lime, although very efficient, are not environmentally friendly as they leave major carbon footprints, therefore the demand for sustainable stabilization methods is escalating. This research investigates the potential of two different polymers e.g., a biopolymer derived from organic source, and an inorganic commercially manufactured polymer, as viable alternatives for soil stabilization. The current study focuses on exploring the efficacy of polymers stabilized soil in improving the engineering or geotechnical properties such as plasticity, compressibility, shear strength, and stiffness behavior.The research methodology involves using locally available high plastic clay for stabilization using two different types of polymers and performing laboratory experiments to analyze the strength parameters of the stabilized soil. Xanthan Gum (XG) is a biopolymer which is being studied is used in the percentages of 0.5%, 1.0% and 1.5% by dry weight of soil mass to understand the mechanism of biopolymer-soil interactions and to conclude optimum percentage suitable for stabilization in terms of technical and economical value. Similarly, Soiltac (ST) a vinyl copolymer inorganic polymer is used in 1.5% of dry mass of soil (optimum dosage as per previous literature) to compare its effectiveness with that of Xanthan Gum. After the determination of Atterberg limits and Optimum Moisture Content (OMC) and Maximum Dry Density (MDD), the samples were subjected to tests such as Unconfined Compressive Strength (UCS), Ultrasonic Pulse Velocity (UPV), Resilient Modulus (RM) test and Consolidation test. The prepared UCS samples were cured for 0, 7, 14, and 28 days in open air condition before performing test on them. Atterberg limits test on untreated Carbondale Soil were conducted to classify the soil as CH (Clay with high compressibility) type as per USCS (Unified Soil Classification System) classification. While tests on treated sample showed significant increasement in Liquid Limit (LL), slight increment in Plastic Limit (PL), thus quite surge in the Plasticity Index (PI) with increase in XG percentage in the soil. UCS value increased with the increase in percentage addition of XG. Also, UCS results from both untreated and polymer treated samples showed increase in compressive strength with increase in curing period. UCS value increased from 417.75 psi to 490.24 psi, 504.05 psi, and 542.91 psi for 0.5%, 1.0%, and 1.5% XG addition, respectively. This increase in UCS value was 17.35%, 20.66%, and 29.96% for the corresponding XG concentrations. The treated samples had a significant increase in the UCS for all the curing period in comparison to their respectively cured untreated sample. The percentages increase in the UCS for 1.5% XG sample in comparison to untreated sample cured for the same period is 6.45%, 59.57%, and 29.96%, respectively for 7, 14 and 28 days of curing. However, for the zero-day test, the UCS of 1.5% XG stabilized sample was found to be less than the zero-day untreated sample. With the addition of ST polymer, the UCS value increased for all the curing period while comparing with the UCS of untreated soil for the same curing period. The UCS of the ST treated soil increased from 58.56 psi to 467.367 psi when cured for 0 and 28 days which is an increase of 698.1 % i.e. 7 times the strength at 0 day. When UPV (Ultrasound Pulse Velocity) tests were compared with the UCS value for the same sample, the result showed that the higher UPV value corresponded to the higher UCS value. This relationship was supported by the high degree of correlation between the two measurements. The consolidation test showed that the Compression Index (Cc) of XG stabilized soil decreased as the percentage of XG added increased. Cc decreased from 0.2795 for pure Carbondale Soil (CS) to 0.2003 for 1.5% XG addition which is a drop of 28.33%. Likewise, Cc decreased by 3.0% and 19.33% for 0.5% and 1.0% XG doses respectively. The primary aim of this study is to simplify the understanding of the Resilient Modulus (RM) test, which yields vital data for pavement design. The efficacy of inclusion of stabilizer was further substantiated by RM testing which confirmed the enhancement of soil resilient qualities compared to the untreated soil. The RM values exhibited a growing trend, indicating an enhancement in the soil's stiffness and capacity to endure repetitive loads. This attribute is extremely important for applications such as the construction of pavements and foundations that are subjected to dynamic loads. The samples containing 1.0% XG showed significant increases in their RM values. Specifically, the RM values increased by 18.5%, 40%, and 39.5% after being cured for 7, 14, and 28 days, respectively, at a confining pressure of 6 psi. Similarly, the RM for the case of ST ranges from 15227.60 psi for 0 days of curing and 2 psi of confining stress to 45375 psi for 28 days of curing and 6 psi of confining pressure. The performance of ST against XG is higher.

L’objectif principal a été d’élaborer de nouveaux revêtements hybrides O/I de morphologie contrôlée afin de répondre des exigences de haute stabilité thermique (300°C) et résistance à la rayure et ayant des propriétés mécaniques spécifiques. Pour répondre à ces attentes, une phase inorganique est générée in-situ par des réactions d’hydrolyse/condensation d’un précurseur inorganique silicié (TEOS) au sein de matrices organiques de microstructures variées : polyesters hyperramifiés (Boltorn H20 and H40), oligoesters ramifiés (Synthoester et dérivés tanniques). Les nombreuses fonctions hydroxyles de la composante organique et leur forme spécifique permettent, dans les conditions de synthèse choisies, de contrôler les interactions entre les phases organiques et inorganiques et retarder les mécanismes de séparation de phases induite lors de la condensation du TEOS. Les matériaux hybrides ont été analysés par TEM, SAXS, ATG et DMA, microscratch testeur. L’influence de la masse molaire, de la teneur en composés inorganiques, de la teneur en fonctions hydroxyle de la composante organique sur la morphologie finale et les propriétés thermiques et mécaniques de surface. / This study focuses on coatings based on news O/I hybrid coatings having a specific morphology to improve resistance to heat, abrasion and scratch as well as mechanical properties. To obtain and control the hybrid morphology, inorganic domains are generated in-situ via sol-gel chemistry based on hydrolysis/condensation reactions of metal alcoxydes (TEOS) into an organic polymer: hyperbranched polyesters (HBP Boltorn H20 and H40) and branched oligoesters (Synthoester, tannic acids). Which ones are high hydroxy functionalized, dense structure and peculiar shape are exploited to control the interactions between the organic and inorganic phases. The hybrid materials were characterized by TEM, SAXS, TGA, DMA, and microscratch tester. We investigated the influence of weight fraction of silica and of hydroxyl functionality of organic component on one side, and the influence of condensation degree on the other side, on the final morphology and thermal and mechanical properties.

Ce travail de thèse a porté sur le développement de revêtements organiques/inorganiques photopolymérisables superhydrophobes à partir de procédés d’élaboration simples associés à des produits commerciaux largement diffusés. Pour cela, des revêtements à matrice polyuréthane acrylate (PUA), intrinsèquement hydrophiles, incluant différents composés à base de silicium ont été élaborés par enduction ou pulvérisation. L’objectif a été d’apporter en surface des revêtements une structuration multi-échelle et une chimie à caractère hydrophobe nécessaires pour atteindre la superhydrophobie, c’est-à-dire un angle de contact avec l’eau supérieur à 150° et une hystérésis de mouillage inférieure à 10°. L’introduction de molécules de polysilsesquioxane polyédrique (POSS), présentant un ligand acrylate et sept ligands isobutyle, a apporté une nanostructuration et un comportement hydrophobe aux revêtements PUA à des concentrations très faibles (≤ 1% en masse.). Cependant, la rugosité apportée se révèle trop faible et cette stratégie ne peut aboutir à la superhydrophobie des revêtements. L’introduction de particules de silice pyrogénée, modifiées en surface par des chaînes polydiméthylsiloxane, a permis d’établir une structuration multi-échelle et une chimie à caractère hydrophobe à la surface des revêtements PUA, leur conférant ainsi la superhydrophobie. De plus, le procédé d’élaboration a joué un rôle majeur sur les modifications physico-chimiques de surface des revêtements : la superhydrophobie est obtenue à une concentration relativement élevée de 30 et 60% en masse de silice pyrogénée respectivement par pulvérisation et enduction. Afin de diminuer ces concentrations, la combinaison des deux stratégies précédentes, c’est-à-dire l’introduction simultanée de POSS et de silice pyrogénée, a été considérée. Ceci a permis d’exacerber le caractère hydrophobe des revêtements tout en préservant la rugosité établie par la silice pyrogénée. Cette approche a conduit à la diminution de la concentration de silice nécessaire pour obtenir la superhydrophobie dans le cas des revêtements élaborés par pulvérisation. / This work deals with the development of organic/inorganic superhydrophobic UV-curable coatings manufactured through simple processes and from commercially available products. To achieve this goal, a hydrophilic polyurethane acrylate matrix (PUA) was used, in which several silicon-based compounds were introduced. The coatings were deposited using either bar- or spray-coating. The main objective was to structure the surface thanks to a multiscale roughness, while bringing a hydrophobic character, two properties needed to obtain a superhydrophobic coating (defined by a water contact angle superior to 150° and a water contact angle hysteresis inferior to 10°). The introduction of polyhedral oligomeric silsesquioxane molecules (POSS), presenting one acrylate and seven isobutyl ligands, brought a nanostructuration and a hydrophobic behavior to PUA coatings, even at low concentrations (≤ 1%wt.). However, the roughness obtained was not sufficient to bring the superhydrophobicity to the coatings.The introduction of fumed silica particles, functionalized by PDMS chains, established multiscale roughness and hydrophobic behavior at the surface, leading to superhydrophobic coatings. Moreover, the process had a high influence on physico-chemical modifications at the coatings’surface: superhydrophobicity is obtained for a relatively high concentration of fumed silica, 30%wt. and 60%wt. respectively for spray and bar-coating. In order to decrease these concentrations, we tried the combination of the two previous strategies: introduction of POSS molecules and fumed silica particles. This path raised the hydrophobic behavior of the coatings while keeping intact the roughness brought by fumed silica particles. This approach allowed to decrease the silica concentration needed to obtain superhydrophobicity for spray-coated coatings.

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