<div> <p>Fiber reinforced polymer composites are widely used in manufacturing advanced light weight structures for the aerospace, automotive, and energy sectors owing to their superior stiffness and strength. With the increasing use of composites, there is an increasing need to monitor the health of these structures during their lifetime. Currently, health monitoring in filament wound composites is facilitated by embedding piezoelectrics and optical fibers in the composite during the manufacturing process. However, the incorporation of these sensing elements introduces sites of stress concentration which could lead to progressive damage accumulation. In addition to introducing weak spots in the structure, they also make the manufacturing procedure difficult. </p> <p> </p> <p>Alternatively, nanofiller modification of the matrix imparts conductivity which can be leveraged for real time health monitoring with fewer changes to the manufacturing method. Well dispersed nanofillers act as an integrated sensing network. Damage or strain severs the well-connected nanofiller network thereby causing a local change in conductivity. The self-sensing capabilities of these modified composites can be combined with low cost, minimally invasive imaging modalities such as electrical impedance tomography (EIT) for damage detection. To date, however, EIT has exclusively been used for damage detection in planar coupons. These simple plate-like structures are not representative of real-world complex geometries. This thesis advances the state of the art in conductivity-based structural health monitoring (SHM) and nondestructive evaluation (NDE) by addressing this limitation of EIT. The current study will look into damage detection of a non-planar multiply connected domain – a filament-wound glass fiber/epoxy tube modified by carbon black (CB) filler. The results show that EIT is able to detect through holes as small as 7.94 mm in a tube with length-to-diameter ratio of 132.4 mm-to-66.2 mm (aspect ratio of 2:1). Further, the sensitivity of EIT to damage improved with decreasing tube aspect ratio. EIT was also successful in detecting sub-surface damage induced by low velocity impacts. These results indicate that EIT has much greater potential for composite SHM and NDE than prevailing work limited to planar geometries suggest.</p> </div> <br>

Abstract This thesis describes a detailed investigation of new glass 10Li₂O−10Na₂O−20K₂O−60MoO₃ (LNKM), ceramic (α-MoO₃) and ceramic-commercial glass (PZ29-GO17, rutile TiO₂-GO17) composites to satisfy the future requirements for ultra-low fabrication temperature materials and their associated processes. The initial part of the thesis is devoted to the development of the LNKM glass by a glass-melting and quenching process, followed by an investigation into its structural, microstructural and microwave dielectric properties. The prepared glass had ultra-low glass transition and melting temperatures of 198 and 350 °C, respectively. The glass pellet heat-treated at 300 °C had a relative permittivity (εr) of 4.85 and a dielectric loss (tan δ) of 0.0009 at 9.9 GHz. The temperature dependence of the relative permittivity was (τε) 291 ppm/°C. Another part of the work concerns α-MoO₃ ceramic, its preparation by uniaxial pressing and sintering at 650 °C followed by an investigation of its structural, microstructural, thermal and microwave dielectric properties. It had an εr of 6.6, tan δ of 0.00013 (at 9.9 GHz) and τε of 140 ppm/°C. In addition to this, a functional ultra-low temperature co-fired composite was developed based on commercial PZ29 and 50 wt.% of GO17 glass followed by tape casting and co-firing with Ag at 450 °C. The average values of the piezoelectric (d₃₃) and voltage (g₃₃) coefficients were 17 pC/N and 30 mV/N, respectively. The sintered sample had an average CTE value of 6.9 ppm/°C measured in the temperature range of 100–300 °C. The εr and tan δ of the sintered substrates were 57.8 and 0.05 at 2.4 GHz, respectively. Additionally, a new ceramic-glass composite was developed using rutile TiO₂-GO17, and co-fired with Ag at 400 °C. It had an average CTE value of 8.3 ppm/°C measured in the temperature range of 100–300 °C. This composite substrate showed εr of 15.5 and tan δ 0.003, at 9.9 GHz. Moreover, it also had τε of -400 ppm/°C at 9.9 GHz measured in the temperature range of −40 to 80 °C. The findings of the thesis reveal the feasibility of the ultra-low temperature co-fired ceramic (ULTCC) technology for high-frequency telecommunication devices as well as for electronics packages. Additionally, a first step to develop functional ULTCC has been taken. / Tiivistelmä Tässä väitöskirjassa kuvataan uuden lasin 10Li₂O−10Na₂O−20K₂O−60MoO₃ (LNKM), keraamin (α-MoO₃) sekä keraami-lasi (PZ29-GO17, rutiili TiO₂-GO17) komposiittien tutkimustulokset, jotka mahdollistavat tulevaisuuden sähkökeraamisten materiaalien ja komponenttien valmistuksen ultra-matalissa valmistuslämpötiloissa. Väitöskirjan alkuosa keskittyy LNKM lasin kehitykseen lasin sulatus- ja karkaisuprosessilla, sekä tämän materiaalin mikrorakenteen sekä mikroaaltoalueen dielektristen ominaisuuksien tarkasteluun. Valmistetulla lasilla oli ultra-matala lasittumislämpötila 198 °C sekä sulamislämpötila 350 °C. Lasipelletin, joka lämpökäsiteltiin 300 °C:ssa, suhteellinen permittiivisyys (εr) oli 4,85 ja dielektriset häviöt (tan δ) 0,0009 9,9 GHz taajuudella. Suhteellisen permittiivisyyden lämpötilariippuvuus (τε) oli 291 ppm/°C. Toinen osa työtä käsittelee α-MoO₃ keraamia, josta valmistettiin näytteet mikrorakenne ja mikroaaltoalueen dielektristen ominaisuuksien tutkimuksiin aksiaalisella puristuksella ja sintraamalla 650 °C:ssa. Valmistetun materiaalin suhteellinen permittiivisyys oli 6,6, häviöt 0,00013 (9,9 GHz:ssa) ja permittiivisyyden lämpötilariippuvuus 140 ppm/°C. Näiden lisäksi kehitettiin toiminnallinen ultra-matalan lämpötilan yhteissintrattu komposiitti perustuen kaupalliseen pietsosähköiseen keraamiin (PZ29) ja lasiin (GO17). Komposiitista valmistetiin monikerrosrakenne nauhavalulla ja yhteissintraamalla hopeaelektrodien kanssa 450 °C:ssa. Keskimääräiset arvot pietsosähköiselle varausvakiolle (d₃₃) sekä jännitevakiolle (g₃₃) olivat 17 pC/N ja 30 mV/N. Sintratun näytteen keskimääräinen lämpölaajenemiskerroin oli 8,3 ppm/°C lämpötila-alueella 100–300 °C. Tämän komposiittisubstraatin suhteellinen permittiivisyys oli 15,5 ja häviötangentti 0,003 9,9 GHz:n taajuudella. Lisäksi suhteellisen permittiivisyyden lämpötilariippuvuus oli -400 ppm/°C samalla 9,9 GHz:n taajuudella, kun lämpötilan mittausalue oli −40–80 °C. Tämän väitöstyön tulokset osoittavat ultra-matalan lämpötilan yhteissintrattavan keraamiteknologian (ULTCC) soveltuvuuden korkean taajuuden tietoliikennesovelluksiin ja elektroniikan pakkausteknologiaan. Lisäksi työssä on otettu ensimmäiset askeleet funktionaalisten ULTCC materiaalien kehittämiseksi.

Within the field of neuroprosthetics the possibility to use implanted electrodes for communication with the nervous system is explored. Much effort is put into the material aspects of the electrode implant to increase charge injection capacity, suppress foreign body response and build micro sized electrode arrays allowing close contact with neurons. Conducting polymers, in particular poly(3,4-ethylene dioxythiophene) (PEDOT), have been suggested as materials highly interesting for such neural communication electrodes. The possibility to tailor the material both mechanically and biochemically to suit specific applications, is a substantial benefit with polymers when compared to metals. PEDOT also have hybrid charge transfer properties, including both electronic and ionic conduction, which allow for highly efficient charge injection.   Part of this thesis describes a method of tailoring PEDOT through exchanging the counter ion used in electropolymerisation process. Commonly used surfactants can thereby be excluded and instead, different biomolecules can be incorporated into the polymer. The electrochemical characteristics of the polymer film depend on the ion. PEDOT electropolymerised with heparin was here determined to have the most advantageous properties. In vitro methods were applied to confirm non-cytotoxicity of the formed PEDOT:biomolecular composites. In addition, biocompatibility was affirmed for PEDOT:heparin by evaluation of inflammatory response and neuron density when implanted in rodent cortex.   One advantage with PEDOT often stated, is its high stability compared to other conducting polymers. A battery of tests simulating the biological environment was therefore applied to investigate this stability, and especially the influence of the incorporated heparin. These tests showed that there was a decline in the electroactivity of PEDOT over time. This also applied in phosphate buffered saline at body temperature and in the absence of other stressors. The time course of degradation also differed depending on whether the counter ion was the surfactant polystyrene sulphonate or heparin, with a slightly better stability for the former.   One possibility with PEDOT, often overlooked for biological applications, is the use of its semi conducting properties in order to include logic functions in the implant. This thesis presents the concept of using PEDOT electrochemical transistors to construct textile electrode arrays with in-built multiplexing. Using the electrolyte mediated interaction between adjacent PEDOT coated fibres to switch the polymer coat between conducting and non conducting states, then transistor function can be included in the conducting textile. Analogue circuit simulations based on experimentally found transistor characteristics proved the feasibility of these textile arrays. Developments of better polymer coatings, electrolytes and encapsulation techniques for this technology, were also identified to be essential steps in order to make these devices truly useful.   In summary, this work shows the potential of PEDOT to improve neural interfaces in several ways. Some weaknesses of the polymer and the polymer electronics are presented and this, together with the epidemiological data, should point in the direction for future studies within this field. / QC 20100623

This thesis begins with a brief overview of current strategies used in the synthesis of side-chain functionalizad polymers and materials. The discussion then focuses more explicitly on transition metal-based motifs and methodologies that are employed in polymer functionalization and continues with a more detailed overview of this field. The primary hypothesis that is addressed herein is that combining the versatility and strength of metal-ligand interactions with the efficiency and functional group tolerance of ROMP comprises a useful method of generating a variety of functionalized polymers and materials via side-chain metal coordination. Thus, the goal is to test this hypothesis by synthesizing functionalized polymers with a range of useful properties to demonstrate the relevance and importance of this methodology, by employing several different strategies to show the synthetic ease by which the materials can be realized. The strategies and methods discussed in the synthesis of side-chain functionalized polymers are divided into three subgroups: (1) pre-polymerization functionalization, in which all of the modifications take place on the monomer with polymerization as the last step, (2) post-polymerization functionalization, in which the polymer itself is subsequently modified, and (3) combinations of the first two strategies. It is shown that useful functional polymers and materials can be synthesized by any of the above strategies, and representative examples of each are given in both the introduction and in the body of work presented. Modes of functionalization are all based on transition metal coordination, and polymerizations are primarily carried out via ROMP. Metal coordination is shown to be a useful technique for functionalizing polymers, to creating supported emissive complexes, to modulating solution viscosity. Finally, conclusions are drawn regarding the various strategies presented herein, and potential future directions are discussed.

The motivations for the research issues addressed in this thesis are based on the needs of the aerospace structural analysis and the design community. The specific focus is related to the characterization and shock induced chemical reactions of multi-functional structural-energetic materials that are also know as the reactive structural materials and their reaction capabilities. Usually motivation for selection of aerospace structural materials is to realize required strength characteristics and favorable strength to weight ratios. The term strength implies resistance to loads experienced during the service life of the structure, including resistance to fatigue loads, corrosion and other extreme conditions. Thus, basically the structural materials are single function materials that resist loads experienced during the service life of the structure. However, it is desirable to select materials that are capable of offering more than one basic function of strength. Very often, the second function is the capability to provide functions of sensing and actuation. In this thesis, the second function is different. The second function is the energetic characteristics. Thus, the choice of dual functions of the material are the structural characteristics and energetic characteristics. These materials are also known by other names such as the reactive material structures or dual functional structural energetic materials. Specifically the selected reactive materials include mixtures of selected metals and metal oxides that are also known as thermite mixtures, reacting intermetallic combinations and oxidizing materials. There are several techniques that are available to synthesize these structural energetic materials or reactive material structures and new synthesis techniques constitute an open research area. The focus of this thesis, however, is the characterization of chemical reactions of reactive material structures that involve two or more solids (or condensed matter). The subject of studies of the shock or thermally induced chemical reactions of the two solids comprising these reactive materials, from first principles, is a relatively new field of study. The published literature on ab initio principles or quantum mechanics based approach contains the ab initio or ab initio-molecular dynamics studies in related fields of a solid and a gas. One such study in the literature involves a gas and a solid. This is an investigation of the adsorption of gasses such as carbon monoxide (CO) on Tungsten. The motivation for these studies is to synthesize alternate or synthetic fuel technology by Fischer-Tropsch process. In this thesis these studies are first to establish the procedure for solid-solid reaction and then to extend that to consider the effects of mechanical strain and temperature on the binding energy and chemisorptions of CO on tungsten. Then in this thesis, similar studies are also conducted on the effect of mechanical strain and temperature on the binding energies of Titanium and hydrogen. The motivations are again to understand the method and extend the method to such solid-solid reactions. A second motivation is to seek strained conditions that favor hydrogen storage and strain conditions that release hydrogen easily when needed. Following the establishment of ab initio and ab initio studies of chemical reactions between a solid and a gas, the next step of research is to study thermally induced chemical reaction between two solids (Ni+Al). Thus, specific new studies of the thesis are as follows: 1. Ab initio Studies of Binding energies associated with chemisorption of (a) CO on W surfaces (111, and 100) at elevated temperatures and strains and (b) adsorption of hydrogen in titanium base. 2. Equations of state of mixtures of reactive material structures from ab initio methods 3. Ab initio studies of the reaction initiation, transition states and reaction products of intermetallic mixtures of (Ni+Al) at elevated temperatures and strains. 4. Press-cure synthesis of Nano-nickel and nano-aluminum based reactive material structures and DTA tests to study experimentally initiation of chemical reactions, due to thermal energy input.

In this thesis the magnetic properties of novel amorphous magnetic materials grown on a flexible substrate of polyethylene naphthalate and a silicon wafer have been analyzed and characterized. The analyzed films are two films of amorphous Cobalt-Iron-Zirconium(Co36Fe53Zr11 &amp; Co37Fe55Zr8) grown on the flexible substrate and two films of amorphous (Fe89Zr11) doped with boron (B). The B is implanted in a lattice of rings with inner diameter of 10 μm and outer diameter of 20 μm and with the distance between the center of the rings of either 50 μm or 25 μm. The composition in the doped region is Fe80Zr10B10. Various magneto-optical Kerr effect(MOKE) magnetometers are used to measure hysteresis loops of the samples and a superconducting quantum interference device (SQUID) is used to find the volume magnetization of the flexible samples. To measure the anisotropy in the flexible films a series of sample holders has been developed to measure various amount of stress using the same sample in magneto-optical magnetometers. The stress induced uniaxial anisotropy is found by measuring hysteresis loops of the flexible samples while bending them with different curvatures. The induced anisotropy is related to the magnetostriction and the magnetostriction constants is estimated for the two flexible samples by assuming values for Young’s modulus and Poisson’s ratio. The estimated values for the magnetostriction constant are found to vary with the amount of Zr and to be in the correct order of magnitude for magnetic films. The implanted B rings with the short distance of 25 μm between the center showed to have some interaction between the rings. This conclusion is drawn after analyzing first order reversal curves of the samples and looking at the domains under a MOKE-microscope. At very low temperatures the (unimplanted) FeZr matrix is ferromagnetic and seem to have an anti-ferromagnetic coupling with the B rings. At room temperature the rings are still ferromagnetic and they couple to each other.

Microporous membranes act as selective barriers and play an important role in industrial gas separation and water purification. The permeability of such membranes is inversely proportional to their thickness. Synthetic two-dimensional materials (2DMs), with a thickness of one to a few atoms or monomer-units are ideal candidates for developing separation membranes. In this Progress Report, we present groundbreaking advances in the design, synthesis, processing, and application of 2DMs for gas and ion separations, as well as water desalination. After the introduction in Section 1, this report describes the syntheses, structures, and mechanical properties of 2DMs in Section 2. In Section 3, we will discuss the established methods for processing 2DMs into selective permeation membranes and address the separation mechanism and their performances. Finally, current challenges and emerging research directions, which need to be addressed for developing next generation separation membranes, are summarized in the Conclusion and Perspective.

Cette thèse se concentre sur la synthèse et l’analyse photophysique de complexes de Pt(II) luminescents and leur assemblage après agrégation. Multiples motifs supramoléculaires ont été utilisé pour acquérir un contrôle sur l’assemblage de ces complexes plan-carrés.Des ossatures de type couronne-éther furent attachés à des complexes métalliques phosphorescents pour donner un bouton supramoléculaire qui peut être actionné par des cations potassium. De plus, l’altération de l’arrangement de l’empilage des Pt(II) après coordination d’un ligand fut exploité pour la réalisation d’un senseur chimique qui peut être utilisé pour la détection différentielle d’aza-hétérocylces. Par ailleurs, l’installation d’un motif pont hydrogène à un complexe de Pt(II) luminescent fut établie, donnant un composé ayant un organisation 2D sur graphène. Finalement, des complexes de Pt(II) amphiphiles qui s’auto-assemblent en solution aqueuse dans des agrégats hautement luminescents furent synthétisés. La série de complexes soluble dans l’eau, chargés négativement ou neutres furent caractérisés par rapport à leurs paramètres photophysiques et leurs interactions avec des protéines capsides virales. / The presented thesis focused on the synthesis and photophysical investigation of luminescent Pt(II) complexes and their resulting assemblies that form upon aggregation. Multiple supramolecular motifs were utilized in order to gain control over the assembling behavior of the square-planar complexes. Crown-ether scaffolds were tethered with the phosphorescent metal complexes rendering a supramolecular switch that can be triggered by potassium cations. Moreover, alteration of the Pt(II)-stacking arrangement upon ligand coordination was exploited to realize a chemosensor that can be employed for of differential detection of aza-heterocycles. Furthermore, the installation of a H-bond motif to a luminescent Pt(II) complex was established, which resulted in a compound forming a two-dimensional organization on graphene. Finally, amphiphilic Pt(II) complexes were synthesized that self-assemble into highly luminescent aggregates in aqueous solutions. The series of water soluble neutral and negatively charged metal complexes were characterized with respect to their photophysical parameters and their interactions with virus coat proteins.

<p>Microparticles have been investigated not only as feedstock spherical or amorphous bulk materials used for shape molding, but also as agents that can perform work in the micron scale. The fabrication of microparticles with active properties of self-propulsion, self-assembly, and mobility with enhanced mechanical, thermal, and chemical properties is of particular interest for emerging technologies such as drug delivery, micro-robotics, micro energy generation/harvesting, and MEMS. Conventional fabrication methods can produce several complex particle shapes in one fabrication session or hundreds of spheroid shaped particles per second. Innovative techniques, as flow lithography, have demonstrated control over particle form and composition for continuous fabrication cycles. In recent years predefined shape polymer microparticles have been fabricated as well as ceramic microparticles through suspension processing with these set of techniques. Even though ceramic materials have been fabricated, there is still a strong need to increment the palette of available materials to be processed via flow lithography. We have pioneered the production of shaped ceramic microparticles by Stop-Flow Lithography (SFL) using preceramic polymers, providing control of particle size and shape in the range of 1 – 1000 μm. The principal arranged technique (SFL) combines aspects of PDMS-based microfluidics and photolithography for the continuous cyclable fabrication of microparticles with predefined shapes. The PDMS microchannel devices used were fabricated with vinyl film molds in a laminar hood avoiding the need for a cleanroom, procedure that reduced fabrication costs. After a fabrication session, the preceramic polymer microparticles were collected, washed, and dried before entering an inert atmosphere furnace for pyrolysis. Additionally, by treating the material initially as liquid polymer, special properties can be added by converting it into an emulsion or a suspension. Microparticles were functionalized by introducing porosity and magnetic nanoparticles in the preceramic polymer matrix. The porous characteristic of a particle leads to an increase in surface area, allowing the particle to be infiltrated with a catalyzer or act as a chemical/physical carrier, and the magnetic behavior of the particles allows a controllable trajectory with defined external magnetic fields. These two properties can be used to fabricate bifunctional microparticles to serve as drug carriers through human arteries and veins for drug delivery purposes. We successfully fabricated solid and functional ceramic microparticles in the 10 – 50 μm range with predefined shapes as hexagons, gears, triangles, and ovals. This system is an economical route to fabricate functional defined shape particles that can serve as microrobots to perform tasks in liquid media.</p>

<div>Recently, energy crisis and environment pollution has become global issues and there is a great demand for developing green and renewable energy system. At the same time, advancements in materials production, device fabrication, and flexible circuit has led to the huge prosperity of wearable devices, which also requires facile and efficient approaches to power these ubiquitous electronics. Piezoelectric nanogenerators and triboelectric nanogenerators have attracted enormous interest in recent years due to their capacity of transferring the ambient mechanical energy into desired electricity, and also the potential of working as self-powered sensors. However, there still exists some obstacles in the aspect of materials synthesis, device fabrication, and also the sensor performance optimization as well as their application exploration.</div><div>Here in this research, several different materials possessing the piezoelectric and triboelectric properties (selenium nanowires, tellurium nanowires, natural polymer hydrogel) have been successfully synthesized, and also a few novel manufacturing techniques (additive manufacturing) have been implemented for the fabrication of wearable sensors. The piezoelectric and triboelectric nanogenerators developed could effectively convert the mechanical energy into electricity for an energy conversion purpose, and also their application as self-powered human-integrated sensors have also been demonstrated, like achieving a real-time monitoring of radial artery pulses. Other applications of the developed sensors, such as serving as electric heaters and infrared cloaking devices are also presented here. This research is expected to have a positive impact and immediate relevance to many societally pervasive areas, e.g. energy and environment, biomedical electronics, and human-machine interface.</div><div><br></div>