Nature develops several materials with remarkable functional properties composed of comparatively simple base substances. Biological materials are often composites, which optime the conformation to their function. On the other hand, synthetic materials are designed a priori, structuring them according to the performance to be achieved. 3D printing manufacturing is the most direct method for specific component production and earmarks the sample with material and geometry designed ad-hoc for a defined purpose, starting from a biomimetic approach to functional structures. The technique has the advantage of being quick, accurate, and with a limited waste of materials. The sample printing occurs through the deposition of material layer by layer. Furthermore, the material is often a composite, which matches the characteristics of components with different geometry and properties, achieving better mechanical and physical performances. This thesis analyses the mechanics of natural and custom-made composites: the spider body and the manufacturing of metallic and non-metallic graphene composites. The spider body is investigated in different sections of the exoskeleton and specifically the fangs. The study involves the mechanical characterization of the single components by the nanoindentation technique, with a special focus on the hardness and Young's modulus. The experimental results were mapped, purposing to present an accurate comparison of the mechanical properties of the spider body. The different stiffness of components is due to the tuning of the same basic material (the cuticle, i.e. mainly composed of chitin) for achieving different mechanical functions, which have improved the animal adaptation to specific evolutive requirements. The synthetic composites, suitable for 3D printing fabrication, are metallic and non-metallic matrices combined with carbon-based fillers. Non-metallic graphene composites are multiscale compounds. Specifically, the material is a blend of acrylonitrile-butadiene-styrene (ABS) matrix and different percentages of micro-carbon fibers (MCF). In the second step, nanoscale filler of carbon nanotubes (CNT) or graphene nanoplatelets (GNP) are added to the base mixture. The production process of composite materials followed a specific protocol for the optimal procedure and the machine parameters, as also foreseen in the literature. This method allowed the control over the percentages of the different materials to be adopted and ensured a homogeneous distribution of fillers in the plastic matrix. Multiscale compounds provide the basic materials for the extrusion of fused filaments, suitable for 3D printing of the samples. The composites were tested in the configuration of compression moulded sheets, as reference tests, and also in the corresponding 3D printed specimens. The addition of the micro-filler inside the ABS matrix caused a notable increment in stiffness and a slight increase in strength, with a significant reduction in deformation at the break. Concurrently, the addition of nanofillers was very effective in improving electrical conductivity compared to pure ABS and micro-composites, even at the lowest filler content. Composites with GNP as a nano-filler had a good impact on the stiffness of the materials, while the electrical conductivity of the composites is favoured by the presence of CNTs. Moreover, the extrusion of the filament and the print of fused filament fabrication led to the creation of voids within the structure, causing a significant loss of mechanical properties and a slight improvement in the electrical conductivity of the multiscale moulded composites. The final aim of this work is the identification of 3D-printed multiscale composites capable of the best matching of mechanical and electrical properties among the different compounds proposed. Since structures with metallic matrix and high mechanical performances are suitable for aerospace and automotive industry applications, metallic graphene composites are studied in the additive manufacturing sector. A comprehensive study of the mechanical and electrical properties of an innovative copper-graphene oxide composite (Cu-GO) was developed in collaboration with Fondazione E. Amaldi, in Rome. An extensive survey campaign on the working conditions was developed, leading to the definition of an optimal protocol of printing parameters for obtaining the samples with the highest density. The composite powders were prepared following two different routes to disperse the nanofiller into Cu matrix and, afterward, were processed by selective laser melting (SLM) technique. Analyses of the morphology, macroscopic and microscopic structure, and degree of oxidation of the printed samples were performed. Samples prepared followed the mechanical mixing procedure showed a better response to the 3D printing process in all tests. The mechanical characterization has instead provided a clear increase in the resistance of the material prepared with the ultrasonicated bath method, despite the greater porosity of specimens. The interesting comparison obtained between samples from different routes highlights the influence of powder preparation and working conditions on the printing results. We hope that the research could be useful to investigate in detail the potential applications suitable for composites in different technological fields and stimulate further comparative analysis.

Fast-bränsle-raketer (SRM) har funnit sin plats i en stor mängd tillämpningar sedan deras framkomst mer än 2000 år sedan. En SRMs prestanda är förutbestämd av geometrin av drivmedelskrutet och är begränsad av gjutningsmetoden, som idag främst används i produktion. Forskning inom 3D-skrivning av drivmedelskrut har undersökt nya komplexa geometrier som kan öka prestandan. Studier kring 3D-skrivning med UV-härdning är få till antalet och undersöks i detta projekt. Ett bindemedel av polyuretandiakrylat (PUDA) har syntetiserats och därefter karakteriserats, med och utan diverse monomerer genom dragprovsmätningar och differentialkalorimetri (DSC). Tillsats av tvärbindarna 1,6-hexandioldiakrylat (HDDA) samt trimetylolpropantriakrylat (TMPTA) till PUDA producerade ett mer sprött material. Denna skillnaden var mer påtaglig för TMPTA än HDDA, vilket tillskrivs den högre akrylatfunktionaliteten i den förstnämnda. Den kommersiella produkten Ebecryl 113 har karakteriserats med inerta fyllmedel. Härddjupet (DOC) undersöktes med Ebecryl 113 i ett experiment, vilket påvisade en minskning av härddjupet med ökande mängder aluminium. Orsaken är troligen de reflektiva egenskaperna för UV-ljus som aluminium innehar. Reologiska studier utfördes, från vilka en minskning i viskositet påvisades till följd av en ökad polydispersitet i partikelstorlekarna. 3D-skrivning med kolvextrudering och påföljande härdning med UV-strålning utforskades. Detta visade utmaningar med tekniken som behövs bemästras. I synnerhet uppmärksammades fasseparation och residuell härdning från reflekterat UV-ljus som begränsande faktorer för fortsatt arbete. / Solid rocket motors (SRMs) have found their place in many applications since their conception more than 2000 years ago. The performance of SRMs is determined by the geometry of the propellant grain and is limited by the cast-and-mould production method typically used today. Research has been made on 3D printing propellant grains to explore new complex geometries, which may increase performance. Studies on 3D printing techniques using UV curing are limited and are in this work investigated. A polyurethane diacrylate (PUDA) binder was synthesized and then characterized, with and without various monomers by tensile testing and differential scanning calorimetry. Additions of the crosslinkers 1,6-hexanediol diacrylate (HDDA) and trimethylolpropane triacrylate (TMPTA) to PUDA rendered the final product more brittle. This change was more noticeable for TMPTA than HDDA, as the former has a higher acrylate functionality. The commercial product Ebecryl 113 was also characterized with inert fillers added. A depth of cure (DOC) study with Ebecryl 113 was conducted, which showed a decrease in DOC with increasing amounts of aluminium. This is attributed to the reflective properties of aluminium in the UV spectrum. Rheological studies were conducted and a decrease in viscosity could be seen as a result of increasing the polydispersity of particle sizes. A 3D printing technique using plunger extrusion followed by UV curing was explored, which highlighted challenges which need to be overcome. Most notably, phase separation and residual curing from scattered UV rays are limiting factors for future work.

Les polymères conjugués semi-conducteurs sont des matériaux prometteurs pour des applications en optoélectronique et pour la fabrication de dispositifs de conversion d'énergie flexibles. Ils sont toutefois difficilement mis en forme en raison de la rigidité de leur structure. Le poly(3-hexylthiophène) (P3HT) est souvent utilisé comme polymère conjugué organique modèle. Sa mise en forme et ses propriétés peuvent être optimisées en l'incorporant dans une matrice polymère et en favorisant l’orientation moléculaire de ses chaînes. Cette orientation peut être induite dans un matériau lors de sa mise en forme, notamment lors de la préparation de fibres par électrofilage. Le projet vise à préparer des matériaux optimisant l'orientation du P3HT et à développer des outils pour caractériser l'organisation moléculaire du P3HT dans ces matériaux. Plus spécifiquement, la première étude consiste à comprendre l'effet de la matrice polymère sur le comportement du P3HT dans des nanofibres électrofilées. Celles-ci sont préparées en mélangeant le P3HT à une matrice polymère amorphe de poly(méthacrylate de méthyle) (PMMA) atactique ou fortement cristalline de poly(oxyde d'éthylène) (POE), et l’orientation des chaînes de P3HT est mesurée par spectroscopie Raman. Les résultats montrent que la capacité du POE à cristalliser, contrairement au PMMA, contraint les chaînes du P3HT à s'orienter le long de l’axe de la fibre, ce qui devrait améliorer ses propriétés de transport de charge. La calorimétrie différentielle à balayage et la microscopie optique et électronique à balayage permettent respectivement d'analyser les propriétés thermiques et d'imager la morphologie des nanomatériaux. La seconde étude est de développer une approche pour identifier la transition vitreuse du P3HT dans des nanofibres électrofilées et des impressions 3D composées d’un mélange P3HT-POE. Nous suivons alors l'évolution de l’état d'agrégation du P3HT par spectroscopie de fluorescence et le déplacement de sa bande Raman associée au mode d’élongation C=C sur une gamme de températures afin d'observer sa transition de phase vitreuse à l'échelle du nanoobjet individuel. Une preuve de concept est réalisée par des analyses sur des films minces à base de P3HT pour ensuite analyser les échantillons d’intérêt. Les résultats de spectroscopie Raman et de fluorescence sur les nanomatériaux de P3HT sont comparés aux analyses DSC sur les matériaux macroscopiques. Le projet améliorera d'une part notre capacité à caractériser les nanomatériaux de P3HT et, d'autre part, à en optimiser les propriétés. De manière plus générale, nos résultats conduiront à terme à une meilleure compréhension des relations structure-mise en forme-propriété-fonction des polymères conjugués, contribuant à la préparation de nouveaux matériaux électroniques organiques plus performants. / Conjugated polymers are promising semiconducting materials for applications in flexible optoelectronic and energy conversion devices. However, they are difficult to process because of the rigidity of their polymer backbone. Poly(3-hexylthiophene) (P3HT) is often used as a model organic conjugated polymer. Its processing and its properties can be improved by incorporating it into a polymer matrix and by favoring the molecular orientation of its chains. This orientation can be induced in a material during its processing, notably during the preparation of fibers by electrospinning. The project aims to prepare materials optimizing the orientation of P3HT and to develop tools to characterize the molecular organization of P3HT in these materials. More specifically, the first study consists of understanding the effect of the polymer matrix on the behaviour of P3HT in electrospun nanofibers. These nanofibers are prepared by mixing P3HT with an amorphous atactic poly(methyl methacrylate) (PMMA) or highly crystalline poly(ethylene oxide) (PEO) polymer matrix, and the orientation of the P3HT chains is measured by Raman spectroscopy. The results show that the capability of POE to crystallize, unlike PMMA, constrains the chains of P3HT to orient themselves along the fiber axis, which could improve its charge transport properties. Differential scanning calorimetry and optical and scanning electron microscopy make it possible, respectively, to analyze the thermal properties and to image the morphology of the nanomaterials. The second study is to develop an approach to identify the glass transition temperature of P3HT in electrospun nanofibers and 3D prints composed of a P3HT-PEO blend. We then follow the evolution of the aggregation state of P3HT by fluorescence spectroscopy and the shift of the Raman band associated with the C=C elongation mode over a range of temperatures to observe its glass transition temperature at the scale of the individual nanoobject. A proof of concept is first realized by carrying out analyses on thin films based on P3HT, followed by the analysis of the samples of interest. Raman and fluorescence spectroscopy results on P3HT-containing nanomaterials are compared to DSC analyses on macroscopic materials. The project will improve our ability to characterize P3HT nanomaterials and to optimize their properties. More generally, our results will ultimately lead to a better understanding of the structure-processing-property-function relationships of conjugated polymers, contributing to the preparation of new, more efficient organic electronic materials.

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<p dir="ltr">The gastrointestinal (GI) tract and its diverse microbial community play a significant role in overall health, impacting various aspects such as metabolism, physiology, nutrition, and immune function. Disruptions in the gut microbiota have been associated with metabolic diseases, colorectal cancer, diabetes, obesity, inflammatory bowel disease, Alzheimer's disease, and depression. Despite recognizing the importance of the gut microbiota, the interrelationship between microbiota, diet, and disease prevention remains unclear. Current techniques for monitoring the microbiome often rely on fecal samples or invasive endoscopic procedures, limiting the understanding of spatial variations in the gut microbiota and posing invasiveness challenges. To address these limitations, this dissertation focuses on the design and development of an electronic-free smart capsule platform capable of targeted sampling of GI fluid within specific regions of the GI tract. The capsule can be retrieved for subsequent bacterial culture and sequencing analysis. The capsule design is based on stimuli-responsive polymers and superabsorbent hydrogels, chosen for their proven safety, compatibility, and scalability. By leveraging the pH variation across the GI tract, the pH-sensitive polymeric coatings dissolve at the desired region, activating the sampling process. The superabsorbent hydrogel inside the capsule collects the sampled GI fluid and facilitates capsule closure upon completion of sampling. Systematic studies were conducted to identify suitable pH-responsive polymer coatings, superabsorbent hydrogels, and processing conditions that effectively operated within the physiological conditions of the GI tract. The technology's effectiveness and safety were validated through rigorous <i>in vitro</i> and <i>in vivo</i> studies using pig models. These studies demonstrated the potential of the technology for targeted sampling of GI fluid in both small and large intestinal regions, enabling subsequent bacterial culture and gene sequencing analysis. Additionally, the capsule design was enhanced with the integration of a metal tracer, enabling traceability throughout the GI tract using X-ray imaging and portable metal detectors for ambulatory screening. This technology holds promise as a non-invasive tool for studying real-time metabolic and molecular interactions among the host, diet, and microbiota in challenging-to-access GI regions. Its application in clinical studies can provide new insights into diet-host-microbiome interactions and contribute to addressing the burden faced by patients and their families dealing with GI-related diseases.</p>

The purpose of this thesis is to develop a simple Direct Ink Writing (DIW) method for fabricating intrinsically stretchable microsupercapacitors as ef- fective on-chip energy storage devices for the emerging stretchable electron- ics. Using the printing method for fabricating intrinsically stretchable elec- tronic components remains a novel approach. In this thesis, interdigitated structures of intrinsically stretchable electrodes were printed on a stretchable thermoplastic polyurethane (TPU) substrate using a formulated ink based on Poly(3,4-ethylenedioxythiophene):Polystyrene Sulfonate. Formulated elec- trolytes based on Poly(4-styrene Sulfonic Acid) and Phosphoric Acid were applied to the electrodes to complete the fabrication of microsupercapacitors. Cyclic Voltammetry (CV), Galvanostatic Charge-Discharge (GCD) and Elec- trochemical Impedance Spectroscopy (EIS) were used to characterize the per- formance of the devices. The stretchability of the electrodes was also mea- sured. Results from CV-measurements revealed a maximum capacitance of740 µF cm−2 at a scan rate of 5 mV s−1. GCD-measurements showed a capaci- tance of 952 µF cm−2 for the same device and an equivalent series resistance of approximately 7 kΩ. The printed electrodes exhibited a stretchability of 80%. The results show the feasibility of fabricating intrinsically stretchable energystorage devices using commercially available materials and a simple 3D print- ing technique. This method could be used as a high-throughput and low-cost method for stretchable electronics applications. / Syftet med detta arbete är att utveckla en simpel Direct Ink Writing (DIW) metod för framställning av intrinsiskt sträckbara mikrosuperkondensatorer som effektiva on-chip energilagrinsenheter i kommande sträckbar elektronik. Användandet av DIW för att tillverka intrinsiskt sträckbara elektroniska kom- ponenter är ett nytt tillvägagångssätt. I detta arbete trycktes interdigiterade strukturer av intrinsiskt sträckbara elektroder på ett sträckbart termoplastiskt polyuretan (TPU) substrat genom att använda ett formulerat bläck baserat på Poly(3,4-etylendioxitiofen):Polystyren Sulfonat (PEDOT:PSS). Formuler- ade elektrolyter baserade på Poly(4-styrensulfonsyra) och Fosforsyra applicer- ades på elektroderna för att färdigställa tillverkningen av mikrosuperkonden- satorer. Cyklisk Voltammetri (CV), Galvanostatisk uppladdning-urladdning (eng. GCD) och Elektrokemisk Impedansspektroskopi (EIS) användes för att karaktärisera enheternas prestanda. Bläckets sträckbarhet uppmättes också. Resultaten från CV-mätningar visade att den maximala kapacitansen var 742µF cm−2 vid skanningsfrekvensen 5 mV s−1. Kapacitansen från GCD-mätningar var 952 µF cm−2 för samma enhet och den ekvivalenta serieresistansen var cirka 7 kΩ. Sträckbarheten som de tryckta elektroderna uppvisade var 80%. . Re- sultaten påvisar möjligheten att kunna framställa intrinsiskt sträckbara en-ergilagringsenheter genom att använda kommersiellt tillgängliga material och en simpel metod för friformsframställning. Denna metod skulle kunna använ- das för att framställa sträckbara elektroniska komponenter till låg kostnad och med hög produktionstakt.

Purpose: This paper will present insight to the methodology and results of the experimental characterization of Acrylonitrile Butadiene Styrene (ABS) using Fused Deposition Modeling (FDM). The work in this research explored the effects of print orientation, surface treatment, and ultraviolet (UV) light degradation with the utilization of Digital Image Correlation (DIC) on ABS tensile specimens. Design/methodology: ABS specimens were printed at three build orientations (flat (0 degrees), 45 degrees, and up-right (90 degrees)). Each of these specimens were treated with three different surface treatments including a control (acrylic paint, Cyanoacrylate, and Diglycidyl Bisphenol A) followed by exposure to UV light to the respective batches. This experiment design will provide tensile direction properties with the effect of thermoset coatings and UV degradation. Dogbone FDM specimens based on ASTM standard D638 type IV were printed on a Stratasys Dimension SST (Soluble Support Technology) 1200es 3D Printer and loaded into a MTS Landmark Servohydraulic Test Systems. Analysis was preformed on the fracture section of the tensile specimens utilized DIC and comparing Ultimate Tensile Strength (UTS) and Ultimate Fracture Strength (UFS). Findings: From the results UV light did not play a large factor in the strength of the specimens. The print orientation showed the largest anisotropic behavior where some specimens experienced as much as a 54% difference in ultimate tensile strength. Thermoset coated specimens experienced a maximum of 2% increase in strength for the Cyanoacrylate and Diglycidyl Bisphenol A specimens where the acrylic paint and natural did not. Several findings were of value when looking at the stress strain plots. Originality/value: This paper provides knowledge to the limited work on print build orientation, thermoset coatings and, UV light on ABS specimens. Very little to no work has been done on these three properties. This paper can serve as the foundation of future work on external applications on ABS plastics.

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