Disorder is an inherent component of real materials, with significant implications for their application in functional devices. Despite this, the theoretical modelling of disorder remains restricted, primarily due to the large simulation cells required to adequately represent disordered systems, and the associated computational costs. This has been remedied in part by the increased availability of resources for high performance computing. In this thesis, using a combination of computational techniques, primarily density functional theory and ab initio as well as classical molecular dynamics, we investigate disorder in two broad categories – physical and chemical disorder, in three distinct classes of materials: palladium nanoparticles, the negative thermal expansion cuprite Ag2O and the complex quaternary chalcogenide Cu2ZnSnS4, known commonly as kesterite. The ‘physical’ disorder discussed in the thesis constitutes shape- and adsorption-induced mechanical softening on the surface of Palladium nanocrystals used for nanocatalysis. This includes one study on the the adsorption of organic capping agents, and another on the adsorption of oxygen molecules and the subsequent oxidation of Pd. In the former, it was observed that the strain effect due to adsorption-induced surface disorder is significantly greater than that due to variations in surface termination, i.e. nanoparticle shape. Moreover in the latter case, different crystallographic facets with different degrees of disorder were found to affect the spin-flip induced activation of oxygen atoms, relevant to the catalytic oxygen reduction reaction in hydrogen fuel cells. In each case, the computational results were combined with a sophisticated, phenomenological whole powder pattern modeling of X-ray diffraction data primarily from synchrotron radiation, leading to an accurate characterization of the Debye-Waller coefficient, which was established as a reliable metric for disorder in crystalline systems. In the case of Ag2O instead, we demonstrated that the large experimental Debye-Waller coefficient was due to thermal diffuse scattering arising from the strong distortion of the Ag4O coordination tetrahedra. The second form of disorder which was investigated is ‘chemical’ disorder, which refers to cation disorder in the quaternary chalcogenide Cu2ZnSnS4 studied for its performance as a thermoelectric material. Similar to the studies on palladium, the disorder was quantified through the Debye-Waller coefficient using molecular dynamics simulations, this time from ab initio methods, and compared with X-ray diffraction data from a synchrotron source. The ordered phase of CZTS is known to crystallize in a tetragonal phase, with alternating Cu-Zn and Cu-Sn cation layers sandwiched between sulfur layers. Two forms of cation disorder were studied: disorder only in the Cu-Zn layer, leading to a disordered tetragonal phase, and full cation site randomization, leading to a disordered cubic polymorph. In the former case, it was found that the higher symmetry of the disordered tetragonal structure led to an average symmetrization of the nearest neighborhood of each individual cation, as a result of which there was a convergence of bands at the valence band maximum, leading to an experimentally observed increase in p-type carrier concentration. In the case of CZTS with full cation disorder, inhomogenous bond led to favorable modifications of the electronic and phonon properties, allowing for a simultaneous improvement of the experimentally measured electrical and thermal conductivities as well as the Seebeck coefficients. Finally, by studying the atypical electronic band structure of this cubic polymorph, we were able to identify topologically non-trivial behavior evidence of bulk band inversion, robust surface states, and an adiabatically continuous connection to a known TI phase. As such, we were able predict disordered cubic CZTS to be the first disorder-induced topological Anderson insulator in a real material system.

Commercially available high-performance thermoelectric materials are often rare or toxic and therefore unsustainable. The present thesis work makes a case for eco-friendly, earth-abundant, and non-toxic p-type ceramic Cu2SnS3 (CTS, hereafter) and, in general, the use of disordered materials for thermoelectric applications. The detailed study of polymorphism, synthesis conditions, porosity, grain size, and doping provides a systematic and in-depth experimental and computational analysis of thermoelectric properties and stability of CTS. These results can be generalized for numerous thermoelectric materials and other applications. Moreover, a case for functioning thermoelectric generators using non-toxic and cost-effective materials is also presented. The thesis begins with a brief introduction to thermoelectricity, followed by a literature review and justification of the choice of the subject. The second chapter puts forward a novel approach to stabilize a disordered CTS polymorph without any chemical alteration through high-energy reactive ball milling. The third chapter deals with the stability of disordered samples under different synthesis and sintering conditions, highlighting the effect of synthesis environment, microstructure, and porosity. The fourth chapter employed a novel, facile, and cost-effective two-step synthesis method (high-energy ball milling combined with spark plasma sintering) to synthesize CTS bulk samples. The two-step synthesis method was able to constrain the CTS grain growth in the nanometric range, revealing the conductive nature of the CTS surfaces. The next chapter explores combining the two-step synthesis method with Ag substitution at the Sn lattice site to improve CTS's thermoelectric performance further. In the final stages of the thesis work, thin film thermoelectric generators were fabricated using CTS and similar chalcogenides, demonstrating power output comparable to existing thermoelectric materials used in the medium temperature range. The final chapter summarizes outlooks and future perspectives stemming from this research work.

Scientists are continuously fascinated by the high degree of sophistication found in natural materials, arising from evolutionary optimisation. In living organisms, nature provides a wide variety of materials, architectures, systems and functions, often based on weak constituents at the lower scales. One of the most extensively studied natural materials is spider silk, renowned for its outstanding mechanical properties, which include exceptional strength and toughness. Owing to its wide range of properties, which vary depending on factors such as the type of silk (up to seven) that each spider can produce, and the species of spider, it can be considered a class of semi-crystalline polymeric material. Indeed, spider silk cleverly combines, depending on the application required, the great deformability of an amorphous phase with the stiffness and strength conferred by pseudo-crystals consisting of specific secondary structures of some of the proteins constituting the material. Based on the countless studies conducted on spider silk, it is now also clear that its remarkable performance are the result of a sophisticated optimisation of the material's hierarchical structure. Nevertheless, many of the multiscale mechanisms that give rise to the striking macroscopic properties are still unclear. Many open problems are also related to the relevant effects of environmental conditions and in particular on temperature and humidity, strongly conditioning the mechanical performances. In this thesis, aimed at unveiling some of these open problems, we introduce a multiscale model for the thermo-hygro-mechanical response, starting with the influence of water molecules modifying the microstructure, up to the effects at the macroscopic scale, including softening, increase in elongation at break and supercontraction, i.e. the shortening (up to half the initial length) of the spider threads in wet environments. Thereafter, we describe how the supercontraction effect can be adopted to obtain humidity-driven actuators, and in particular, we determine the maximum actuation force depending on the silk properties at the molecular scale and on the constraining system representing other silk threads or the actuated device. The spider silk actuation properties turned out to be extraordinary, making spider silk potentially the best performing humidity-driven actuator known to date in terms of work density. As observed in many natural materials, spider silks are characterized by a strong variability in both chemical and structural organization, as for example described in the recently published experimental database of properties at different scales of about a thousand different spider silks, where evident correlations among quantities are scarce. This large variability makes the theoretical understanding of the observed material behavior, in relation of the complex hierarchical structure, particularly intriguing. To address this novel amount of experimental data without losing sight of theoretical analytical modelling, we propose a new data modelling methodology to obtain simple and interpretable relationships linking quantities at different scales. In particular, we employ a symbolic regression technique, known as 'Evolutionary Polynomial Regression', which integrates regression capabilities with the Genetic Programming paradigm, enabling the derivation of explicit analytical formulas, finally delivering a deeper comprehension of the analysed physical phenomenon. Eventually, we provide insights to improve our multiscale theoretical model accounting for the humidity effects on spider silks. This approach may represent a proof of concept for modelling in fields governed by multiscale, hierarchical differential equations. We believe that the analytical description of the macroscopic behaviour from microscale properties is of great value both for the full understanding of biological materials, as well as in the perspective of bioinspired materials and structures.

Corrosion poses an ongoing challenge in materials science. This thesis delves into the intricate phenomenon of filiform corrosion (FFC) in organic-coated steel, investigating its mechanisms and proposing novel prevention strategies. Despite extensive empirical research and theoretical models, uncertainties persist about the precise nature of FFC on steel substrates, the causes, and the electrochemical process. This work systematically explores the electrochemical underpinnings of FFC, shedding light on the influencing factors and the complex interactions within the metal-paint interface. Advanced electrochemical methods are developed to systematically study and replicate the FFC phenomenon, providing a deeper understanding of this often underestimated issue in industrial applications. Leveraging insights from FFC research in other alloys, such as aluminum and magnesium, this thesis significantly advances our comprehension of FFC's mechanisms and underlying chemical reactions. Furthermore, the research introduces novel techniques for evaluating existing corrosion mitigation solutions and proposes innovative strategies. A breakthrough innovation is presented, involving the development and characterization of a ceramic composite pigment system based on calcium and aluminum loaded with an organic inhibitor. This promises substantial advancements in corrosion protection for steel structures. Additionally, commercially available technologies are being assessed for their effectiveness in safeguarding against FFC also using a simulated electrochemical approach, with the aim of validating this suggested methodology. In summary, this thesis aims to provide a comprehensive study of filiform corrosion for organic-coated steel substrates, offering a deeper understanding of its mechanisms, novel prevention strategies, and innovative characterization techniques.

The atomic mean square displacement (MSD,  ̄(σ_i^2 ) ) is often used in computational materials science studies to calculate measurable properties from the atomic trajectories of simulations; for example, the diffusion coefficient, which according to Einstein relations (Einstein 1905) on the random walk is 1/6 of the slope of the trend of  ̄(σ_i^2 ) vs. time (Chandler 1987). Equally relevant is the mean square relative displacement (MSRD,  ̄(σ_ij^2 )), used in X-ray Spectroscopies, mainly EXAFS, to describe the atomic disorder in solids (Calvin 2013) (Fornasini 2014). Less known is the relevance of the MSRD in X-ray scattering from nanoparticles. In particular, in Total Scattering methods (Pair Distribution Function and Debye Scattering Equation), which rely on an atomistic description of the nanoparticles, the MSRD is the key to distinguish dynamic (thermal) and static disorder (Krivoglaz 1969) (Kuhs 2006). Interestingly, the trend of the MRSD with the distance is characteristic of the nanoparticle shape, an aspect investigated in some detail in this Thesis work. More generally it can be shown that beyond the expected effect of nanocrystal size, the shape alters the contribution of the surface, which is quite relevant for the MSRD. The importance of the shape and of the surface region holds also in case of clusters of nanoparticles, not only in isolated particles. Besides the MSRD, the atomic configurations simulated by molecular dynamics (MD) can also be used to calculate the so-called Warren plot (or diagram), originally introduced in the seminal work of Warren & Averbach of the †̃50s to describe the effects of plastic deformation in metals (Warren B.E. 1950). Recent work has shown how to obtain Warren plots from the analysis of the diffraction line profiles according to the Whole Powder Pattern Modelling (WPPM) (L. M. Scardi P. 2002) (Scardi P 2017) (P. E.-W. Scardi 2018), in particular from the analysis of the strain component of the diffraction peak profile broadening. As proposed in this work, If the Warren plot can be calculated directly from MD simulations, then it is possible to proceed backwards, and construct more reliable strain functions from an atomistic knowledge of the local atomic displacement caused by static and dynamic disorder components. This thesis is divided in two main parts, discussing two different but complementary topics: atomistic modelling and calculations of displacement quantities, application of the above results to experimental case studies, based on the modelling of diffraction data from nanocrystalline systems. We start by describing the atomistic simulations and vibrational properties calculated for several atomic configurations. The main case study concerns Palladium nanoparticles of different sizes and shapes, for which we show that vibrational properties and correlation properties between atoms pairs are greatly influenced by the geometric shape of the nanoparticle and to a lesser extent by their size. The interest is on truncated cubes, i.e. cubes whose edges and corners are progressively removed, as in the series of so-called Wulff solids, ranging from the cubic to the octahedral shape (Wulff G. 1901). As shown in (ii), these are the object of several experimental studies. The developed methodologies are nevertheless applicable to other cases, like the clusters of nanocrystals observed in powders produced by high-energy ball milling, which is also a topic discussed in (ii). The work aims to show a general approach to atomistic modelling, both for isolated nanoparticles with definite shapes, and grains of unspecified shape in plastically deformed polycrystalline materials. We then use the values for displacement quantities (e.g., MSD, MSRD) calculated for the simulated systems to compare them to the experimental results. An underlying fact that seems to hold in all the different cases is that the surface behaviour of nanomaterials has the largest influence on the displacement quantities. For isolated particles we observe strong correlation between displacement quantities and the shape; whereas in the case of a nanocrystalline grain clusters (Figure 1 1) we see that no matter the defects inside the grain, the main contribution to MSRD is given by the grain boundary.

Real-time structural health monitoring is a well established tool for post-earthquake damage estimation. A key component in the monitoring campaign is the approach used for processing the data from the structural health monitoring system. There is a large body of literature on signal processing approaches aimed at identifying ground-motion induced damage in civil engineering structures. This dissertation expands on a specific subgroup of processing approaches dealing with the identification of damage induced high-frequency transients in the monitoring data. The underlying intuition guiding the current research can be formulated in the following hypothesis - the time difference between the occurrence of a high-frequency transient and the closest deformation extremum forward in time is proportional to the degree of damage. A mathematical deduction is provided in support of the above hypothesis followed by a set of shaking table tests. For the purposes of this research two shaking table tests of reinforced concrete bridge piers were performed. Data from a shaking table test performed by another research group was also analyzed. The cases in which the proposed procedure could find a practical application are examined along with the present limitations.

Tissue engineering (TE) is an interdisciplinary field, in continuous evolution, that possesses as main goal the creation of efficient systems for tissues and organs healing and regeneration. For bone, TE strategies are typically based on the combined use of scaffolds, cells, and bioactive molecules. Different materials were successfully studied and proposed for the fabrication of scaffolds. Among them, silk fibroin (SF) was evaluated as particularly promising for different TE applications, especially for bone tissue regeneration. Silk fibroin, a natural protein forming the structural core of silk filaments, holds biocompatibility, mechanical properties and biodegradation rate suitable for applications in bone regeneration. However, in the past, SF has shown some limitations, especially in terms of bioactivity and effective differentiating ability of hMSCs in regenerating bone tissue. In this work, we wanted to demonstrate that SF, properly processed, chemically modified, and conjugated with selected bioactive species, can be used to prepare different systems: a functionalised scaffold; a bioresorbable material with mineralization ability; an implantable immunomodulatory material. The experimental activities performed and the deep investigation of the properties of the SF-based systems prepared, led to promising results, indicating that SF could be a flexible and powerful platform for the realization of different therapeutic tools. For some of the SF-based systems described in this dissertation, further studies are needed to assess the biological activity of the materials prepared.

Le corpus se compose de trois ouvrages de non-fiction The Soul of London (1905), The Heart of the Country (1906) et The Spirit of the People (1907), regroupés en un seul volume sous le titre England and the English – an Interpretation lors de la publication de la trilogie à New-York en 1907. Cette trilogie a été ensuite éditée en 2003 par Carcanet Press sous la direction de Sara Haslam. Peu étudiées, ces oeuvres ont une existence propre à l'intérieur de la trilogie, au coeur del'oeuvre fordienne, voire au sein de la littérature moderne. Ce travail herméneutique permet de mettre au jour le feuilletage d'un texte prétexte à une réflexion à la fois autobiographique, philosophico-théologique, socio-historique et théorique portant sur l'écriture et l'art en général. Il révèle l'esthétique innovante d'un auteur qui cherchera sans relâche sa place dans le paysage littéraire international, entre impressionnisme et futurisme, et essaiera de recueillir l'adhésion de « l'homme moyen sensible » en la personne de son lecteur, en lui transmettant un message d'amour par le biais d'une langue hybride et plurielle inspirée de la « langue des oiseaux ». Derrière l'Angleterre se dessine la Provence et une esth/éthique du troubadour. / The three books collected in England and the English are The Soul of London (1905), The Heart of the Country (1906) et The Spirit of the People (1907). Although the complete trilogy was edited in New-York in 1907 it was made available to English readers in 2003 only, when Sara Haslam edited the volume for Carcanet Press. This study means to show in what ways those so-called essays are crucial and make sense as a trilogy, within Ford's own work as well as within modern literature. The hermeneutic approach adopted here attempts to decipher a multi-layered text and brings out underlying themes and intertexts that bear on the author's biography as well as on his interests in philosophical, religious, and socio-historical topics and reflect his passion for writing. The trilogy comes out as emblematic of the original aesthetic of a writer who, hovering between impressionism and futurism, tried to find his own way within the international literary landscape. Ford defines and addresses here an homme moyen sensible, very close to his ideal reader and transmits to him a specific message of love resorting to a hybrid, joyful and plural language inherited from the medieval langue desoiseaux. England becomes indistinguishable from Provence and from aesth/ethics connected with its troubadours.

In this study, polypropylene (PP) based nanocomposites were prepared by incorporating different kinds and amounts of silica nanoparticles and graphite nanoplatelets (GNP). The role of various percentages of compatibilizer polypropylene grafted with maleic anhydride (PPgMA) into PP nanocomposites was also investigated. In order to analyze the effect of the manufacturing process on the material’s properties, the samples were produced by (i) melt compounding and compression molding and (ii) extrusion and injection molding. It was found that injection molding provides significantly greater stiffness and strength compared to compression molding for all types of PP nanocomposites. Several characterization techniques were used in order to correlate the microstructure to the physical and mechanical properties of the materials. Both silica and GNP were found to be effective nucleating agents, significantly increasing the crystallization rate during isothermal crystallization and favoring the nucleation of the the β- phase, which manifests superior impact strength and toughness compared to the most common α-form crystals. Graphite nanoplatelets were found more efficient in inducing polymorphism and favoring the formation of a transcrystalline phase on the filler surface. A significant correlation between the tensile modulus, glass transition temperature and the amount of constrained phase, as assessed through tensile and DMA analyses, revealed the presence of a secondary reinforcing mechanisms, which, concurrently to the primary stiffening effect of the high modulus filler, contributes to the enhancement of the bulk properties. A complex constrained phase, responsible for providing a secondary reinforcing mechanism, was modeled as immobilized amorphous and transcrystalline regions located at the filler surface. The non-linear viscoelastic creep of the composites, successfully studied by the application of the time strain superposition principle (TSSP), showed a considerable enhancement of the creep stability in nanocomposites with respect to unfilled PP, especially for higher creep stresses. The study of creep dependance on the temperature showed that the stabilizing effect provided by the nanoparticles was more effective at high temperatures and, considering the time temperature superposition principle (TTSP), at long loading times. The equivalence between the time strain- and time temperature- superposition principle was substantiated by comparing the correspondent superimposed master curves. The nanofilled PP matrices have also been used for the preparation of microcomposites reinforced with short glass fibers (GF). Interfacial shear strength (ISS) was measured by means of the single fiber fragmentation test on various PP/GF microcomposites. Results show that the strength at the fiber/matrix interface can be remarkably increased when using nanocomposite systems, especially in the case of dimethyldichlorosilane-functionalized silica nanoparticles and GNP platelets, and that the improvement is further increased when the nanoparticles are used in combination with PPgMA. The thermodynamic fiber/matrix work of adhesion, estimated by contact angle measurements, showed a good correlation with the ISS values. Hybrid composites reinforced with short glass fibers and nanofillers were produced and characterized in order to investigate how the morphology and the mechanical properties of the composites were affected by the combined effect of two fillers of rather different size scales (i.e. micro- and nano- scale). The stronger fiber/matrix adhesion combined with the enhancement of the matrix properties resulted in superior tensile properties and impact resistance and improved viscoelastic behavior. As means of comparison, thermosetting hybrid composites based on epoxy resin were also produced by incorporation of GNP and short GF.

Due to an increasing attention to environment preservation and the need to accomplish new regulations, a general interest to improve the recyclability of composite materials has recently emerged. In order to fulfill this new requirements, a possible strategy could be represented by the development of so-called "single polymer composites" (SPCs), i.e. composite materials in which both matrix and reinforcement have the same chemical composition. The main advantage of SPCs is that, unlike traditional heterogeneous composites (such as glass- or carbon reinforced polymer composites), they can be entirely melted down at the end of the product life for recycling. After an optimization of the annealing treatment to improve the mechanical properties and thermal stability of the reinforcing phase, SPCs containing Vectran® micro- and nano- fibers as a reinforcement were prepared, and their thermo-mechanical properties and recyclability were investigated using a multidisciplinary approach. Single polymer micro composites (SPMCs) containing up to 30 wt% of reinforcing microfibers showed a outstanding improvement of tensile modulus (up to 160 %) compared with the unfilled matrix. FESEM observations evidenced some pull-out phenomena, indicating a poor interfacial adhesion. After a surface treatment on the reinforcement, a composite containing up to 20 wt% showed a remarkable improvement of almost 180% in the tensile modulus compared with the unfilled matrix. FTIR and thermal analysis evidenced its recyclability. Single polymer nano composites (SPNCs) containing up to 10 vol% of reinforcing nanofibers showed an increase by almost 20% of their tensile modulus and strength in comparison with the unfilled matrix. Optical observations revealed a consolidation problem in the unfilled matrix due to the adapted film-stacking process used. However, the addition of the nanofibers in the composite eliminated the problem. Thermal analysis was used to ensure the SPNCs recyclability. Vectran® single polymer micro- and nano- composites have been proven to be possible candidates to substitute traditional heterogeneous composites materials, with enhanced recyclability features.