O trabalho tem por finalidade o estudo teórico e experimental de ligações em estruturas de madeira com cavilhas de madeira de seção cilíndrica impregnadas com resinas estirênicas. A impregnação da madeira tem como objetivos: diminuir o processo de degradação, retardação ao fogo, melhorar a estabilidade dimensional e aumentar as propriedades de resistência e elasticidade da madeira. Foram determinados experimentalmente as características de resistência e elasticidade do material e posteriormente realizados ensaios de ligações padronizados com solicitação paralela e normal às fibras. Os resultados dos ensaios mostram aumento na resistência de compressão normal até 292% e aumento de 80% no limite de proporcionalidade da ligação. A madeira utilizada para a impregnação foi o Pinus de reflorestamento. / The aim of this work is a theorytical and experimental studies of joints in timber structures with wooden dowels of circular cross section impregnated with styrenic resins. The objetives of wood impregnation are to decrease the deterioration process, to promote fire retardation, to improve dimensional stability and mainly increase the compression strength and stiffiness of wood. The strength and stiffness properties of the material are determined. Standard joints tests are carried out in compression both parallel and perpendicular to grains. The test results increases of compression perpendicular strength up to 292% and the up to 80% proportional limit joint. The wood used for impregnation was Pinus from reforestation sites.

Cette thèse s’inscrit dans le domaine de la catalyse hétérogène pour des applications en raffinage et en pétrochimie. Plus particulièrement, nous avons choisi d’étudier le cas des catalyseurs d’hydrotraitement largement utilisés dans les procédés de conversion du pétrole en carburant. Ces catalyseurs sont constitués d’une phase métallique sulfurée supporté sur un support poreux inorganique.Dans ce travail, nous nous sommes particulièrement intéressés à la compréhension et la modélisation de la première étape de préparation d’un catalyseur d’hydrotraitement : l’étape d’imprégnation. Une méthodologie innovante basée sur la technique d’imagerie RMN qui permet d’observer operando le transport des précurseurs métalliques dans le support et sur la technique d’Imagerie Raman a été développée. Les résolutions spatiales et temporelles obtenues ont permis de valider cette méthodologie pour caractériser l’étape d’imprégnation en termes de phénomènes physiques (capillarité et diffusion) et chimiques (interaction de surface) et pour identifier les descripteurs clés de cette étape.En conclusion, ces travaux permettront un meilleur contrôle de l'étape d'imprégnation et donc du profil de distribution de la phase active, ce qui aura une forte répercussion sur la performance catalytique / The objective of this work is to characterize the impregnation step in terms of physical phenomena (capillarity and diffusion) and chemical phenomena (surface interaction) in order to identify the key descriptors of this step in order to improve the preparation hydrotreating catalysts. This involves monitor spatial and temporally the transport of the species in the impregnation solution within the porosity, more particularly in the case of Ni(Co)MoP/?-Al2O3 catalysts preparation.An original MRI approach has been developed to follow in-situ the impregnation step from a solution of mixed nature with more than one metal precursor in the presence of an additive. MRI provides access to the spatial distribution of all species within the catalyst with a spatial resolution of 39 × 39 µm. Raman imaging allows an identification of the chemical nature of the species in solution with a spatial resolution of 16.2 × 16.2 µm.First, the phenomena involved in the impregnation of model solutions composed of Ni (or Co), were studied by modifying the parameters of the solution. These experiments were then used as the basis for the development of a mathematical model to rationalize the impregnation step. In a second part, this study was extended to the preparation of hydrotreatment catalysts. Several phenomena have been evaluated here, notably the impact of the presence of phosphorus on the transport of Mo species, possible competition of adsorption between P, Co and Mo and the effect of the presence of citric acid.This study allows a better control of the impregnation step and thus of the distribution profile of the active phase, which has an impact on the catalytic performance

Le procédé d’imprégnation en milieu supercritique est une alternative « propre » à l’imprégnation par voie liquide. Entre autres applications, les procédés d’imprégnation peuvent être utilisés pour l’élaboration de systèmes de délivrance de médicaments appliqués aux domaines pharmaceutique et médical. Cette étude porte sur l’élaboration de systèmes de délivrance de médicaments en utilisant l'imprégnation supercritique des principes actifs sur deux types de supports : des matrices polymériques (lentilles intraoculaires) et des matrices poreuses (silices mésoporeuses). Dans le premier cas, des lentilles polymériques intraoculaires (IOLs), utilisées pour la chirurgie de la cataracte, ont été imprégnées par des principes actifs : un anti-inflammatoire (Dexaméthasone 21-phosphate disodium: DXP) et un antibiotique (Ciprofloxacine: CIP). Plus particulièrement, deux types de lentilles ont été étudiés : des IOLs rigides à base de PMMA et des IOLs souples à base de P-HEMA. Les expériences d'imprégnation supercritique ont été effectuées en mode batch et les taux d'imprégnation ont été déterminés par des études de cinétique de relargage des principes actifs. L’influence des conditions opératoires sur l’efficacité de l’imprégnation a été étudiée en réalisant des expériences d’imprégnation préliminaires suivies par des plans d’expériences par la suite. Dans le second cas, une silice mésoporeuse a été utilisée comme support d’imprégnation pour un médicament faiblement hydrosoluble (Fénofibrate), afin d’augmenter sa cinétique de dissolution. L’imprégnation supercritique a été effectuée avec le CO2 pur en faisant varier la pression et le taux de dépressurisation (rapide et lent). / Supercritical impregnation is an attractive “clean” alternative to conventional impregnation processes using generally liquid organic solvents. Among other applications, the impregnation process can be used for the development of controlled drug delivery systems applied to the pharmaceutical and medical fields. This work focuses on the preparation of controlled drug delivery systems using supercritical impregnation of drugs in two kinds of impregnation supports: polymeric matrices (intraocular lenses) and porous supports (mesoporous silica). Firstly, the supercritical impregnation of polymeric intraocular lenses (IOLs), used in cataract surgery, by an anti-inflammatory drug (Dexamethasone 21-phosphate disodium: DXP) and an antibiotic (Ciprofloxacin: CIP), is studied. More particularly, two polymeric IOLs were tested: rigid intraocular lenses made from derivative of PMMA and foldable intraocular lenses made from derivative of P-HEMA. Supercritical impregnations were carried out in a batch mode and the impregnation yields were determined through drug release kinetics studies in a solution simulating the aqueous humor. The influence of operating conditions on impregnation was studied by performing preliminary impregnation experiments followed by experimental designs. The second part of this work deals with the loading of a poorly water-soluble drug (Fenofibrate) in a mesoporous silica for improving drug dissolution kinetics. Supercritical impregnations were carried out with pure CO2 at different pressures (100 to 200 bar) and depressurization rates (rapid and slow).

Doctor Educationis / In summary, it has been shown during this study that bimetallic Fe and Mn containing catalysts can be prepared by wet impregnation and not by ion exchange because of the competition between two different metals at different oxidation number. Only a single metallic phase catalyst could be prepared successfully by using ion exchange. / South Africa

La cérine est connue pour être très performant en tant que support, dans le domaine de l'oxydation catalytique. L'ajout de métaux de transitions améliore en général cette activité. Dans ce travail, l'argent a été ajouté sur la cérine. Deux méthodes de préparation ont été utilisées : l'imprégnation (Imp), connue par la formation de particules de tailles différentes sur la surface du support, et le dépôt-précipitation (DP) qui conduit en général à la formation de nanoparticules dispersées sur la surface et dans la masse du support. Deux séries de catalyseurs x%Ag/CeO₂(Imp) et x%Ag/CeO₂(DP) où x est le pourcentage massique de l'argent par rapport à la cérine, ont été préparés dans le but de comparer leurs propriétés physico-chimiques. Ensuite leurs activités catalytiques dans les réactions d'oxydation. Les catalyseurs ont été caractérisés par différentes techniques telles que la BET, la DRX, la RPE, l'ATD-ATG, la SPX, l'UV et la RTP. Dans les deux séries de catalyseurs, la DRX a montré que des particules de Ag⁰ ont été obtenues pour les fortes teneurs en argent ; ces particules sont plus grosses dans les imprégnés que dans les (DP). La présence des nanoparticules dans les deux séries de solides a été aussi confirmée par l'UV (résonance plasmonique). Ces nanoparticules sont de formes sphériques dans les (DP) et mi-sphériques, ou déformées, dans les (Imp). Trois états d'oxydation : Ag⁰, Ag⁺ et Ag²⁺ ont été identifiés dans les imprégnés et seulement deux : Ag⁰ et Ag⁺ dans les DP. La formation des ions Ag²⁺ semble être due à la présence de AgNO₃ sur la cérine au cours de la calcination du solide, ce qui était le cas pour les imprégnés et non pour les DP. De plus, les deux isotopes ¹⁰⁷Ag²⁺ et ¹⁰⁹Ag²⁺ ont été mis en évidence par la technique de la RPE ; ce résultat est considéré comme original et primordial. Par la suite, les deux séries de catalyseurs ont été testés dans les réacctions d'oxydations catalytique du propène, du monoxyde de carbone et du noir de carbone. Le résultat inattendu dans ce travail c'est que, contrairement à la bibliographie, les catalyseurs imprégnés étaient plus actifs que les (DP) pour les trois réactions. La performance catalytique des imprégnés a été reliée à la présence des espèces Ag²⁺ qui sont absents dans les DP. Autrement exprimé à la présence de trois couples redox Ag²⁺/ Ag⁺, Ag²⁺/ Ag⁰ et Ag⁺/ Ag⁰ dans le cas des solides (Imp), pour seulement un couple redox Ag⁺/ Ag⁰ dans le cas des solides (DP). Une présence adéquate dans les rapports de concentrations de ces trois couples redox dans le catalyseur 10%Ag/CeO₂(Imp) a rendu ce dernier le plus performant comparé aux autres de la même série. / Ceria is a well known support in the world of catalytic oxidation reactions. Adding transition metals tend to enhance the catalytic activity. Silver was used in our work, and was added using two different preparation methods : the impregnation (Imp) and the deposition-precipitation (DP). The first known by the formation of different particles size on the surface of the support, whereas the second is known by the formation of nanoparticles with a good dispersion on the surface and in the bulk of the support. Two catalysts series x%Ag/CeO₂(Imp) and x%Ag/CeO₂(DP) (where x is the weight percentage of silver over ceria) were prepared in order to compare their physico-chemical properties and afterward their catalytic performances in three different oxydation reactions. The catalysts were characterized using BET, XRD, EPR, DSG-TG, XPS, UV and TPR techniques. XRD showed on both series the formation of Ag⁰ particles for the catalysts with high weight percentages. The sizes of these particles are larger in the (Imp) solids compared to the (DP) ones. Beside of these particles, the formation of Ag⁰ nanoparticles was confirmed by the plasmonic resonance in the UV technique. The nanoparticles are spherical in the (DP) solids and half spherical (misshaped) in the (Imp) solids. Three oxidation states were found in the (Imp) catalysts : Ag⁰, Ag⁺ et Ag²⁺ compared to only two in the (DP) : Ag⁰ et Ag⁺. The nitrate present in the AgNO₃ (silver precursor) during the calcination might be the reason of the formation of the Ag²⁺. That is not the case for the (DP) solids. The two isotopes for Ag²⁺ (¹⁰⁷Ag²⁺ and ¹⁰⁹Ag²⁺) were identified with the EPR technique. This result is considered as original and very important. Afterward, the catalysts were tested in the total oxidation of the propylene, carbon monoxide and carbon black. The catalytic results were unexpected and oppose the literature results. (Imp) catalysts showed a higher activity than the (DP) in all the reactions. The catalytic performance of the (Imp) was ascribed to the presence of Ag²⁺ species that are missing in the (DP) catalysts. In other words, this performance is related to the presence of the 3 redox couples Ag²⁺/ Ag⁺, Ag²⁺/ Ag⁰ et Ag⁺/ Ag⁰ for the (Imp), compared to only one : Ag⁺/ Ag⁰ for the (DP). The 10%Ag/CeO₂(Imp) solid showed an appropriate concentration ratio of the redox couples, that's why it showed the highest catalytic activity among the other solids from the same series.

Nonwoven polypropylene has been utilized broadly in various hygienic and medical textile applications because of its excellent mechanical properties, chemical resistance, and minimal expense contrast with other synthetic polymers. However, the insufficiency of surface tethering groups, including adhesion, wettability, and hydrophilicity, some applications are not convenient on nonwoven polypropylene surfaces such as dyeing, printing, attachment of antibacterial and bioactive agents. To stimulate nonwoven polypropylene surface energy, utilization of supercritical carbon dioxide technology provides a resource-efficient and environment-friendly solution compares to other commonly developed wet chemical processes and ionized gas treatment techniques. This thesis investigates the possibility of functional group endorsement from 1,2,3,4-Butanetetracarboxylic acid onto nonwoven polypropylene surface in supercritical carbon dioxide media through impregnation where supercritical carbon dioxide acts as a solvent for the monomer and swelling agent for polypropylene. Two-level three-factor full factorial with a centre point statistical model implemented where pressure ranges from 9MPa to 13MPa, temperature ranges from 60°C to 100°C, and treatment time ranges from 6 hours to 8 hours, to optimize process condition to achieve less hydrophobic surface. Ethanol used as co-solvent and concentration of 1,2,3,4-Butanetetracarboxylic acid utilized 0.4 moles/litre in this investigation. Water contact angle analysis confirms surface functionalization for each treated sample and exhibits the highest decrease in surface hydrophobicity for (11MPa, 80°C, 7hrs) process condition treated sample (contact angle, θ = 114°). Statistical analysis shows the higher significance of temperature factor (p-value 0.008) with the feasibility of selected model efficacy (R2= 0.91). FTIR-ATR analysis authenticates the existence of hydrophilic functional groups (-OH, C=O, and C-O) from 1,2,3,4-Butanetetracarboxylic acid onto nonwoven polypropylene surface. Four stages mass loss thermogram of (11MPa, 80°C, 7hrs) process condition treated sample obtained from thermogravimetric analysis (TGA) confirm impregnation of organic molecules into nonwoven polypropylene matrix. Differential scanning calorimetry (DSC) analysis shows a 7.56% decrease in crystallinity percentage of (11MPa, 80°C, 7hrs) process condition treated sample than non-treated nonwoven polypropylene. In this investigation, each process condition treated nonwoven polypropylene surfaces achieve a less hydrophobic surface due to the impregnation of hydrophilic functional groups from 1,2,3,4-Butanetetracarboxylic acid did not accomplish hydrophilic character. Analysis among carbonyl index and work of adhesion results revealed a decrease in hydrophobicity depend on the concentration of hydrophilic functional groups on polypropylene surface and at the same time rely upon the crystallinity percentage and swelling properties of nonwoven polypropylene.

This experimental study focuses on the links that exist between the mechanical pull-out behaviour of multi-filament yarns embedded in concrete and the impregnation of the yarn by the concrete. To this aim, 5 glass yarns have been embedded in concrete (AR and E glass yarns from assembled or direct roving). A pre-treatment was applied to the yarn before the casting, and was chosen in the following three: wetting, drying or pre-impregnation with a cement slurry. By this way, 15 yarn / pre-treatment combinations were obtained that generate 15 conditions of impregnation of the yarn by the cementitious matrix. In each case, the mechanical properties were determined from a classical pull-out test and the yarns impregnation properties were characterized by two dedicated tests: yarns porosity measurements and along yarn water flow measurements. By studying the relationship between the mechanical behaviour and the physical properties of the impregnated yarns, it is shown that the pre- and post-peak behaviour are mainly connected to the flow rate measured during the water flow measurements, which suggest a specific influence of the connected pores parallel to the filaments and of the penetration depth of the matrix into the yarn. The postpeak and the residual behaviour are moreover linked to the yarn pore volume associated to the disorder induced in the filaments assembly by the penetration of the matrix. The overall result of this work is a contribution to the understanding of the relationship between the impregnation of the yarns and the pull-out behaviour.

Cette thèse développe la synthèse contrôlée et la purification de nanoparticules d’or hybrides, AuNPs stabilisées par des thiols organiques modulant leurs propriétés de surface. Les applications visent la catalyse et le domaine biomédical, impliquant un contrôle poussé des nanoobjets introduits. Les synthèses des AuNPs organiques sont développées à partir de la méthode de Brust, avec le 4-hydroxythiophénol et le 4-méthylthiophénol. Elles conduisent à des nanoparticules hybrides stables d’environ 2 nm. Les fractions de purifications sont analysées par MET, UV-visible, RMN et ATG, caractérisant le cœur d’or, la couche de ligands et leurs interactions. Il apparaît que les AuNPs hybrides présentent un assemblage de thiols en monocouche ou en multicouche. Une nouvelle voie de synthèse directe en phase aqueuse d’AuNPs d’environ 4 nm, stabilisées par le 4-hydroxythiophénol, est ensuite développée. Ces AuNPs sont purifiées par dialyse et caractérisées par MET, UV-visible, RMN et ATG. Les fractions d’AuNPs organiques, présentant différents états de surface, sont imprégnées dans la silice mésoporeuse SBA-15. Les isothermes d’adsorption et la manométrie sous diazote indiquent une bonne dispersion des AuNPs et une insertion dans les canaux. Nous introduisons l’exploration d’applications ciblées. L’utilisation des AuNPs organiques lors de l'oxydation d’alcènes tend à améliorer la sélectivité du sel de manganèse catalytique. Pour le domaine biomédical, les AuNPs aqueuses présentent une bonne dispersibilité en milieux aqueux biocompatibles. Les premiers tests in-vitro sur des cellules de sarcomes humains montrent une faible cytotoxicité et une bonne pénétration intracellulaire. / This Ph.D. work developed the controlled synthesis and purification of hybrid gold nanoparticles AuNPs, stabilized by organic thiols that are tuning their surface properties. The targeted applications are the catalysis and in the biomedical field, requiring a thorough control of the introduced nanoobjects. Syntheses of the organic AuNPs were developed from the Brust method, using 4-hydroxymercaptophenol or 4-methylmercaptophenol, leading to stable hybrid gold nanoparticles of size 2 nm. Purified fractions were characterized using TEM, UV-visible, NMR and TG analysis, issuing key data about the gold core, the organic layer and their interactions. Among the different fractions of AuNPs, the organic thiol ligands appeared to be assembled either as a monolayer or a multilayer pattern. A new direct route for synthesis of aqueous AuNPs of size 4 nm, stabilized by 4-hydroxymercaptophenol, has been developed. The AuNPs were purified using dialysis and characterized by TEM, UV-visible, NMR and TG analysis. Organic AuNPs, exhibiting different surface properties, were impregnated into SBA-15 mesoporous silica. Adsorption isotherms and nitrogen adsorption/desorption studies were in good agreement with the homogeneous distribution of AuNPs and the significant incorporation into the porosity. Finally, exploration of the targeted applications was started. The use of organic AuNPs for alkene oxidation tends to improve the selectivity of manganese salt catalyst. In the biomedical field, the aqueous AuNPs exhibited good dispersibility into biocompatible aqueous solvents. First in-vitro assays involving human sarcoma cells line showed limited cytotoxicity and good cellular uptake.

Novel ceramic membrane cells of BaCe₀.₅Zr₀.₃Y₀.₁₆Zn₀.₀₄O[subscript(3-δ)] (BCZYZ), a proton-conducting oxide, have been developed for electrocatalytic ammonia synthesis. Unlike the industrial Haber-Bosch process, in this work an attempt to synthesise ammonia at atmospheric pressure has been made. The membrane cell fabricated by tape casting and solution impregnation comprises of a 200 μm-thick BCZYZ electrolyte and impregnated electrode composites. Electrocatalysts for anode and cathode were investigated. For the anode, the co-impregnation of Ni and CeO₂ provided excellent electrode performance including high catalytic activity, sintering stability and compatibility with the BCZYZ electrolyte. The best composition was the mixture of 25 wt% NiO and 10 wt% CeO₂. A symmetrical cell prepared with this electrode composition revealed low polarisation resistances of 1.0 and 0.45 Ωcm² in humidified 5% H₂/Ar at 400 and 500 °C, respectively. For the cathode, 25 wt% of impregnated Fe oxide provided a satisfactory performance in non-humidified N₂ atmosphere. Significant amounts of ammonia were produced from the single cell with Ni-CeO₂ anode and Fe oxide cathode at 400-500 °C under atmospheric pressure. Ammonia formation rate was enhanced by Pd catalyst addition and electrochemical performance was improved by Ru addition. The highest ammonia formation rate of 4 x 10⁻⁹ mols⁻¹cm⁻² was attained using the cell with a Pd-modified Fe cathode at 450 °C. The formation reaction of ammonia typically consumed around 1-2.5 % of total applied current while most of the applied current was employed in H⁺ reduction. The total current efficiency of around 90-100 % could be obtained from the membrane cells.

We propose an effective strategy to engineer a unique kind of porous carbon cuboid with tightly anchored cobalt/cobalt oxide nanoparticles (PCC–CoOx) that exhibit outstanding electrochemical performance for many key aspects of lithium-ion battery electrodes. The host carbon cuboid features an ultra-polar surface reflected by its high hydrophilicity and rich surface defects due to high heteroatom doping (N-/O-doping both higher than 10 atom%) as well as hierarchical pore systems. We loaded the porous carbon cuboid with cobalt/cobalt oxide nanoparticles through an impregnation process followed by calcination treatment. The resulting PCC–CoOx anode exhibits superior rate capability (195 mA h g−1 at 20 A g−1) and excellent cycling stability (580 mA h g−1 after 2000 cycles at 1 A g−1 with only 0.0067% capacity loss per cycle). Impressively, even after an ultra-long cycle life exceeding 10 000 cycles at 5 A g−1, the battery can recover to 1050 mA h g−1 at 0.1 A g−1, perhaps the best performance demonstrated so far for lithium storage in cobalt oxide-based electrodes. This study provides a new perspective to engineer long-life, high-power metal oxide-based electrodes for lithium-ion batteries through controlling the surface chemistry of carbon host materials.