Nesse trabalho, foi investigada a obtenção de novos materiais a partir de reações de hidrólise e condensação ácida do (3-aminopropil)trimetoxisilano, que resultaram na formação de nanoestruturas híbridas com grupos amônios e contraíons cloreto (POSS-NH3Cl). As nanoestruturas posteriormente foram submetidas a trocas iônicas durante 0,5, 2, 12 e 48 h, para remoção dos íons cloreto. As análises titulométricas mostraram que a troca iônica ocorreu parcialmente. As partículas de POSS-NH2 formadas apresentam predominância de estruturas em forma de gaiola (T8) octafuncionalizadas. Após a troca iônica, as nanoestruturas possuem capacidade de se autoassociar por meio de interações eletrostáticas formando estruturas do tipo blackberry com aproximadamente 100 nm. Os aglomerados de POSS-NH2 são formados por partículas primárias com tamanho de 1,4 nm em forma de fractal de massa e tamanho de correlação () dependente da quantidade do tempo de troca iônica. Devido à característica eletrostática das partículas foi possível obter filmes híbridos opticamente transparentes com elevado grau de hidrofilicidade. As nanopartículas de POSS-NH2 foram utilizadas como aditivo de lubrificantes de fontes renováveis (ácidos graxos) por meio de reações de amidação direta assistida por micro-ondas, sem o uso de catalisadores. A formação das ligações amidas foi constatada por meio das técnicas FTIR e RMN de 1H, onde observaram-se bandas de deformação angular do NH em 1550 cm-1 e 1120 cm-1 e o aparecimento de um singleto alargado em 6,50 ppm (N-H). Em termos estruturais, para o biolubrificante foi constatado que uma molécula de ácido graxo liga com uma molécula de POSS-NH2, entretanto foi notada ainda a existência de aglomerados após a amidação, conforme resultados de MET dos lubrificantes. O uso de POSS-NH2 reduziu a taxa de oxidação dos biolubrificantes com dependência do tempo de troca iônica das partículas. Todos os biolubrificantes apresentaram comportamento reológico newtoniano, e a viscosidade a 25ºC mostrou-se dependente da quantidade de partículas e não do tempo de troca iônica. A adição de nanopartículas de POSS-NH2 melhorou o desempenho dos biolubrificantes aplicados em superfícies metálicas, visto que tribossistema estudado apresentou valores inferiores e mais estáveis de coeficiente de atrito em comparação com o óleo base. Além disso, os biolubrificantes apresentaram uma elevada capacidade do suporte de carga, que representa a carga crítica para a ocorrência de engripamento (scuffing) do sistema. A resistência ao desgaste das superfícies metálicas variou com a adição de partículas no óleo lubrificante e com os tempos de troca iônica adotados para a síntese das partículas. / Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul, FAPERGS / In this work, was investigated the obtaining of new materials from the hydrolysis and acid condensation reactions of (3-aminopropyl) trimethoxysilane, which resulted in the formation of hybrid nanostructures with ammoniums groups and counter ions chloride (POSS-NH3Cl). The nanostructures were subjected to ion exchange procedures for 0.5, 2, 12 and 48 h for the removal of chloride ions. The titrimetric and volumetric results showed that the ion exchange occurred partially. The synthesized particles are predominantly POSS-NH2 cage-shaped structures (T8). After the ion exchange, the nanostructures have ability to selfassembly through electrostatic interactions forming the blackberry-like structures with approximately 100 nm. The POSS-NH2 cluster are formed by primary particles with a size of 1.4nm structured in form of a mass fractal with correlation length () dependent on the ion exchange time. Due to the electrostatic characteristic of the particles was possible obtained hybrid films optically transparent with a high degree of hydrophilicity. POSS-NH2 nanoparticles were used as additive of lubricants of renewable sources (fatty acids) by means of microwave-assisted direct reactions of amidation, without the use of catalysts. The formation of amide bonds were confirmed through the FTIR and 1H NMR techniques, where angular deformation bands in NH in 1550 cm-1 and 1120 cm-1 and the appearance of an enlarged singlet in 6.50 ppm (NH) were observed. The biolubricants was found that an alloy fatty acid molecule with a POSS, but has not yet noticed the existence of agglomerates after amidation, as TEM results of biolubricants. The POSS-NH2 are bonded individually to only one fatty acid molecule, however it was noted the existence of cluster after amidation reactions, as observed in TEM results of the biolubricants. The addition of POSS-NH2 nanoparticles reduced the oxidation rate of the biolubricants and has dependence on the ion exchange time. All the biolubricants showed a Newtonian rheological behavior and the viscosity at 25°C dependent on the amount of particles and not the exchange time. The addition of POSS-NH2, improved the performance of the biolubricants applied on metallic surfaces, since the studied sliding pair showed lower and more stable values of coefficient of friction, as compared to the base oil. Moreover, the biolubricants showed a high load support capacity, which represents the critical load for the scuffing occurrence of the system. The wear resistance of the metallic surfaces changed with the addition of POSS particles in the lubricant oil and with the ionic exchange time adopted for the synthesis of the particles.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21589号 / 理博第4496号 / 新制||理||1645(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 北川 宏, 教授 竹腰 清乃理, 教授 吉村 一良 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

<div><p>Carbon fibre reinforced polymers (CFRPs) are extensively used in aerospace, automotive and other weight-conscious applications for their high strength-to-weight ratio. Utilization of these lightweight materials unfortunately also involves dealing with damages unlike those seen in traditional monolithic materials. This includes invisible, below-the-surface damages such as matrix cracking, delaminations, fibre breakage, etc. that are difficult to spot outwardly in their early stages. Robust methods of damage detection and health monitoring are hence important. With the intention of avoiding weight addition to the structure to monitor its usability, it would be desirable to utilize an inherent property of these materials, such as its electrical conductivity, as an indicator of damage to render the material as self-sensing.</p> <p>To this end, electrical impedance tomography (EIT) has been explored for damage detection and health monitoring in self-sensing materials due to its ability to spatially localize damage via non-invasive electrical measurements.</p> <p>Presently, EIT has been applied mainly to materials possessing lesser electrical anisotropy than is encountered in CFRPs (e.g. nanofiller-modified polymers and cements), with experimental setups involving electrodes placed at the edges of plates. The inability of EIT to effectively tackle electrical anisotropy limits its usage in CFRP structures. Moreover, most real structures of complex geometries lack well-defined edges on which electrodes can be placed. Therefore, in this thesis, we confront these limitations by presenting a study into the effect of EIT sensitivity matrix formulation and surface-mounted electrodes on damage detection and localization in CFRPs.</p> <p>In this work, the conductivity is modeled as being anisotropic, and the sensitivity matrix is formed using three approaches – with respect to i) a scalar multiple of the conductivity tensor, ii) the in-plane conductivity, and iii) the through-thickness conductivity. It was found that through-hole damages can be adeptly identified with a combination of surface-mounted electrodes and a sensitivity matrix formed with respect to either a scalar multiple of the conductivity tensor or the in-plane conductivity. This theory was first validated on a CFRP plate to detect a single through-hole damage. Furthermore, EIT was also used to successfully detect both through-hole and impact damages on a non-planar airfoil shaped structure.</p> <p>Singular value decomposition (SVD) analysis revealed that the rank of the sensitivity matrix is not affected by the conductivity term with respect to which the sensitivity matrix is formed. The results presented here are an important step towards the transition of EIT based diagnostics to real-life CFRP structures.</p><p></p></div><div><div><br></div></div>

<p dir="ltr">Ceramic/metal composites are being explored as potential replacements for conventional metal alloys in high-temperature components used in aerospace and power generation applications. Co-continuous ceramic/metal composites can offer attractive combinations of properties, such as improved mechanical toughness and thermal conductivity (relative to monolithic ceramics) and enhanced stiffness and corrosion/erosion resistance (relative to monolithic metals). However, development of cost-effective and scalable manufacturing routes to dense, complex-shaped ceramic/metal composites is a non-trivial challenge.</p><p dir="ltr">Chapter 1 of this dissertation is focused on the fabrication of WC/Cu composites using pressureless Cu liquid infiltration. The microstructure, density, porosity, phase content and properties of the resulting WC/Cu composites have been investigated. Mechanical properties, such as flexural strength and Vickers hardness have been evaluated, and the thermal cycling behavior of the WC/Cu composites have been examined. This study successfully demonstrates the fabrication of near-net-shape WC/Cu composites and provides insights into potential applications for such composites.</p><p dir="ltr">In Chapter 2, the limitations of metal alloy-based heat exchangers are discussed, leading to the exploration of alternative materials such as composite of zirconium carbide (ZrC) and tungsten (W). The favorable properties of ZrC/W composites, such as chemical compatibility, low vapor pressure, high thermal conductivity, stiffness, and thermal cyclability are highlighted. The fabrication of ZrC/W composites using reactive infiltration processes, emphasizing the importance of scalable fabrication methods, is also demonstrated.</p><p dir="ltr">Chapter 3 is focused on the fabrication and characterization of functionally graded ZrC/W – WC/Cu composites. These composites have been prepared by immersing WC/Cu preforms in Zr – Cu liquid at different temperatures, and the microstructures and phase distributions have been evaluated. It is observed with the same immersion time, the thickness of the ZrC/W reaction zone decreases with increasing immersion temperature due to the rapid reaction between WC and Zr at higher temperatures. Additionally, a model has been developed to describe the thermal conductivity of the composites as a function of the distance from the external surface. These findings provide insights into the fabrication and properties of functionally-graded composites for potential heat dissipation applications.</p><p dir="ltr">In Chapter 4, the development of a Ti-bearing, Ni-based active metal braze for joining Al₂O₃/Cr composites to Ni-based alloys is discussed. Joining ceramic components to metal parts poses challenges due to material property mismatches and ceramic brittleness. Conventional brazing materials often suffer from oxidation at high temperatures in air which compromises joint integrity. The focus of this chapter is the evaluation of the oxidation behavior of the developed brazing material to assess the suitability of this braze for reliable joining of ceramic-based composites to Ni-based alloys for use in air at high temperatures. Differential scanning calorimetry (DSC) has also been used to evaluate the solidus and liquidus temperatures of the Ni-19Cr-10Si and Ni-18Cr-10Si-4Ti alloys.</p><p><br></p>

<p dir="ltr">Over the past few decades, metamaterials have attracted great research interest due to their extraordinary properties which cannot be easily achieved by natural materials. For example, anisotropic metamaterials that exhibit different properties along different directions, are valuable in different fields of optics. To achieve such anisotropic performance, nanocomposite designs by coupling different materials and functionalities have been demonstrated as an effective approach.</p><p dir="ltr">The goal of this dissertation is to design and fabricate anisotropic multiphase nanocomposite thin films with multifunctionality and tunability. Both transition metal oxides and transition metal nitrides are selected to study due to their high thermal stability, good crystallinity, and unique electromagnetic properties. In addition, different metals, especially plasmonic Au and magnetic Co, are selected as the metallic phase to fabricate nanocomposites. The designs also extend beyond the traditional two-phase nanocomposites to multiphase nanocomposites containing metal, oxide, and nitride, with more metamaterial design possibilities and more functionalities.</p><p dir="ltr">The dissertation consists of the introduction of multiphase nanocomposite thin film and experimental techniques, followed by four research chapters. In the first research chapter, hyperbolic HfO₂-Au with tunable optical properties is fabricated and studied. In the second research chapter, the magnetic Co is introduced into the nanocomposite thin film for multifunctionality design, and the obtained ZrO₂-Co thin film exhibits both hyperbolic optical property and magnetic anisotropy. In the third research chapter, vertically aligned nanocomposite (VAN) design and multilayer design are combined to achieve a complete three-phase HfO₂-Au/TiN-Au multilayer nanocomposite. Such a complete structure can exhibit tunable optical response. In the fourth research chapter, the magnetic Co is combined with the superconducting NbN to explore more applications of such VAN design. Overall, the dissertation work demonstrates various approaches of anisotropic metamaterials designs using oxides, nitrides, and metals. Enhanced functionality and multifunctionalities are demonstrated. Future research is needed for incorporating these new metamaterials designs in optical devices and sensors.</p>

Climent Terol, E. (2012). Design of new hybrid materials: Study of its application in new detection formats and in controlled release applications [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/17939

The concept of creating a hybrid material is motivated by the development of an improved product with acquired properties by amalgamation of components with specific desirable traits. These new attributes can range from improvements upon existing properties, such as strength and durability, to the acquisition of new abilities, such as magnetism and conductivity. Currently, the concept of an organic-inorganic hybrid material typically describes the integration of an inorganic polymer with organically derived proteins. By building on this idea and applying the advanced technologies available today, it is possible to combine living and nonliving components to synthesize functional materials possessing unique abilities of living cells such as self-healing, evolvability, and adaptability. Furthermore, artificial gene regulation, achievable through synthetic biology, allows for an additional dimension of the control of hybrid material function. Here, I genetically engineer E. coli with a tightly controlled artificial protein construct, allowing for inducible expression of different amounts of the surface anchored protein by addition of varying concentrations of L-arabinose. The presence of the surface protein allows the cells to bind nonliving nanoparticle substrates, effectively turning the cells into living crosslinkers. By using the living crosslinker, I was able to successfully synthesize a robust, macroscale living-nonliving hybrid material with magnetic characteristics. Furthermore, by varying the particle size and inducer concentration, the resulting material exhibited alterations in structure and function. Finally, I was able to manipulate material kinetics within a PDMS channel by applying fluctuating magnetic fields and demonstrate material durability. These results demonstrate the ability to manipulate synthesis of living-nonliving hybrid materials, which demonstrate the potential for use in promising applications in areas such as environmental monitoring and micromachining. Additionally, this work serves as a foundational step toward the integration of synthetic biology with tissue engineering by exploiting the possibility of controlling material properties with genetic engineering. / Ph. D. / Creating a hybrid material is appealing because the resulting product has properties from both elements. For example, an example of a hybrid car combines a combustible gas engine for power and an electric drive system to reduce gas emissions. The result is an automobile that is more fuel efficient and environmentally friendly, but does not compromise in power or speed. In other cases, the addition of an element may be in order to improve upon existing properties, such as strength or durability. Alternatively, new elements may introduce new properties such as magnetism or conductivity. Although the current field is more focused toward nonliving organic elements, here, I will introduce a living organic element to my hybrid material. Living organisms allow the introduction of an even wider range of unique abilities such as self-healing, evolvability, and adaptability. Furthermore, through DNA modifications, an additional dimension of the control of hybrid material function may also be introduced. Here, I endow <i>E. coli</i> cells with the ability to produce artificial proteins on their surfaces. Furthermore, I am able to control the amount of protein produced by changing the amount of chemical, L-arabinose, present. The protein anchored to the cell’s surface are able to attach to nonliving magnetic nanoparticles, allowing them to act as living material builders, referred to as crosslinkers. The result is a robust, macroscale livingnonliving hybrid material with magnetic characteristics. Additionally, the sizes of the particles and the amount of the chemical (resulting in corresponding anchored protein concentrations), effect the resulting material and its structure. Finally, a setup was created to observe the material when magnetic force was applied. The results demonstrate unique characteristics of the material, showing its potential for use in applications such as environmental monitoring or micromachining. This work serves as a critical step for the integration of synthetic biology with tissue engineering by exploiting the possibility of controlling material properties with genetic engineering.

<p>Composite materials have become widely used for high-performance applications, particularly in the aerospace industry where annual production volumes are low and a higher part cost can be supported. During the last decades composite materials are beginning to see use in a broader range of applications, including the automotive and sports equipment industries. Simultaneously, there is increasing demand from consumers and regulatory bodies to make cars more fuel efficient and in the case of EV’s longer drive range, which can be accomplished by reducing vehicle weight. Composite materials have high specific stiffnesses and strengths, resulting in weight savings when they are used to replace traditionally metal components. However, in order for widespread adoption of composite parts to be viable for the automotive industry, high-rate manufacturing must be realized to reach the required production volumes and part costs.</p> <p>Toward this goal, advanced composite manufacturing techniques have been developed. These techniques typically combine high automation with careful material selection, which can include fast-curing resins and thermoplastics with adapted melt viscosities and thermomechanical properties. They also allow for complex part geometries to be produced in a single step, reducing the need for additional assembly time. Further, they can be used to easily create multi-material components, which can result in parts that benefit from the desirable mechanical properties of the constituent materials without sacrificing performance.</p> <p>This thesis develops a framework for the design and high-rate manufacture of multi-material components. First, a critical literature review is conducted to develop a clear understanding of existing research into combinations of dissimilar materials, including epoxy/polyamide, thermoplastic elastomer/polyamide, and aluminum/thermoplastic. It is shown that, for all material combinations studied, interfacial delamination and subsequent deformation are the primary energy absorption mechanisms and that manufacturing conditions may affect interfacial bond strength. Based on this foundation, adhesion testing is performed on devoted sample configurations fabricated under controlled molding conditions. For these material combinations, interfacial adhesion can be significantly improved with carefully selected processing temperatures, even to the extent that adhesive bond between dissimilar materials can be stronger than the cohesive bond in the constituent materials. Next, impact and quasi-static indentation testing were performed to determine the effects of interfacial adhesion and part design on crash performance. The materials tested all benefit from the placement of a more ductile material on the impacted side of the sample (top surface), indicating a more favorable dissipation of the contact stresses from the impactor, and a higher strength material on the bottom surface where it can withstand tensile stresses imposed by impact-induced bending. </p> <p> Finally, a complex part consisting of a unidirectional polyamide/carbon fiber preform and a thermoplastic overmold is manufactured via a hybrid overmolding process. Interfacial temperature during overmolding is varied to confirm if the same improvements in interfacial bond strength seen in the compression molding test samples are attainable under realistic high-rate manufacture conditions. Additionally, the preform volume is varied to examine the effect of the preform reinforcement on a part’s bending performance. For this system, varying the preform temperature had no effect on interfacial bond strength. A predictive technical cost model is also used to determine the effect of manufacturing changes on part costs. Increasing the tow volume three-fold increased the absorbed energy by more than 30% and requires an increased cost of only 3.8%. </p> <p>This thesis proves that a tough, multi-material part can be rapidly produced via hybrid overmolding. It was demonstrated that a complex shaped part could be produced at a complete line cycle time of approximately 90 secondsmaking it a viable method to produce high-performance, low-cost components. </p>

This dissertation addresses two topics associated with the assembly of surfactants at the solid-liquid interface for adsorption and materials synthesis. The first is the adsorption of an anionic fluorinated surfactant, tetraethylammonium perfluorooctylsulfonate (TEA-FOS), at the solid/liquid interface. Attenuated total reflection Fourier transform infrared spectroscopy is used to study the adsorption kinetics and average orientation of surfactants at the hydroxylated germanium surface. Atomic force microscopy provides complementary images of the adsorbed layer structure on mica. The adsorption follows unusual three-stage kinetics in which the rate of adsorption starts fast, slows as the surface becomes crowded, and then (surprisingly) accelerates due to nucleation of a heterogeneous multilayer structure. These fast-slow-fast three stage adsorption kinetics are observed for a wide range of concentrations at pH 6, and the rates of the three stages are modulated by pH and salt by tuning electrostatic interactions among surfactants, counterions, and the surface. The results suggest that tetraethylammonium mediates interactions between surfactants and with negatively charged surfaces. The dichroism measurements and AFM are consistent with a mechanism in which TEA-FOS first forms an incomplete layer with chains oriented randomly or somewhat parallel to the surface, followed by formation of flattened multilayer clusters with the chains oriented somewhat normal to the substrate. The second topic is the sol-gel synthesis of mesoporous silica materials using dual surfactant templates. Studies of templating with mixed cetyltrimethylammonium bromide and octyl-beta-D-glucopyranoside surfactants shows that the ternary phase diagram of surfactants in water can be used to predict mesoporous materials structure, and that vapor-phase ammonia treatments can either stabilize the structure or induce swelling by the Maillard reaction. Studies of sol-gel reaction-induced precipitation with demixed hydrocarbon and fluorocarbon cationic surfactant micelles show a wide variety of pore structures. A number of synthesis parameters are adjusted to tune the pore structure, for instance to adjust the size and populations of bimodal mesopores. Selective swelling of the two surfactants by liphophilic and fluorophilic solvents is observed. Finally, proteinaccessible hollow spherical silica particles with mesoporous shells are reported. The methods for engineering mesoporous materials reported here have potential applications in adsorption, controlled drug delivery and for catalysis.

Les minerais de phosphates, principalement exploités pour la production d'acide phosphorique et d'engrais, contiennent une quantité non-négligeable d'uranium (50 à 300 ppm) qui suscite l'intérêt de l'industrie nucléaire. Notre étude s'inscrit dans ce contexte de valorisation de l'uranium en tant que sous-produit de l'industrie des fertilisants.L'objectif de ce travail de thèse a été de mettre au point un matériau hybride, constitué d'un support inorganique sur lequel est greffée une molécule complexante, capable d'extraire sélectivement l'uranium du milieu acide phosphorique. La première étape de notre démarche a consisté à identifier un support inorganique capable de résister aux conditions particulières du milieu acide phosphorique (acidité élevée et milieu très complexant). Pour ce faire, la stabilité chimique et mécanique de différents matériaux, silice, verre et carbone mésoporeux, a été étudiée. Dans un deuxième temps, nous nous sommes intéressés à l'identification et l'optimisation de molécules complexantes spécifiques de l'uranium en milieu acide phosphorique. Ces dernières ont ensuite été greffées sur les supports les plus stables. Enfin, l'efficacité de ces systèmes hybrides a été évaluée lors de tests d'extraction, de sélectivité et de désextraction. / Phosphate rocks are industrially processed in large quantities to produce phosphoric acid and fertilisers. These rocks contain significant concentration of uranium (50 to 300 ppm) which could be interesting for nuclear industry. This work deals with the valorisation of uranium as a by-product from fertiliser industry.The aim of this study is to develop a hybrid material, constituted of an inorganic solid support grafted with an extractant (complexing molecule), which can extract selectively uranium from phosphoric acid medium. The first step of our approach was to identify an inorganic support which is stable under these particular conditions (strong acidity and complexing medium). The chemical and mechanical stability of different mesoporous materials, such as silica, glass and carbon was studied. In a second phase, we focused on the identification and the optimisation of complexing molecules, specific of uranium in phosphoric acid. These ligands were then grafted on the most stable solids. Finally, the efficiency of these hybrid systems was evaluated through different tests of extraction, selectivity and desextraction.