Microelectromechanical systems (MEMS) based artificial sensory hairs for flow sensing have been widely explored, but the processes involved in their fabrication are lithography intensive, making the process quite expensive and cumbersome. Most of these devices are also based on silicon MEMS, which makes the fabrication of out-of plane 3D flow sensors very challenging. This thesis aims to develop new fabrication technologies based on Polymer MEMS, with minimum dependence on lithography for the fabrication of piezoresistive 3D out-of-plane artificial sensory hairs for sensing of air flow. Moreover, the fabrication of a flexible sensor array is proposed and new materials are also explored for the sensing application. Soft lithography based approaches are first investigated for the fabrication of an all elastomer device that is tested in a bench top wind tunnel. Micromolding technologies allow for the mass fabrication of microstructures using a single, reusable mold master that is fabricated by SU-8 photolithography, reducing the need for repetitive processing. Polydimethylsiloxane (PDMS) is used as the device material and sputter deposited gold is used as both the piezoresistive as well as the electrode material for collection of device response. The fabrication results of PDMS to PDMS metal transfer micromolding (MTM) are shown and the limitations of the process are also discussed. A dissolving mold metal transfer micromolding process is then proposed and developed, which overcomes the limitations of the conventional MTM process pertinent to the present application. Testing results of devices fabricated using the dissolving mold process are discussed with emphasis on the role of micro-cr  acking as one failure mode in elastomeric devices with thin film metal electrodes. Finally, a laser microfabrication based approach using thin film Kapton as the device material and an electrically conductive carbon-black elastomer composite as the piezoresistor is proposed and demonstrated. Laminated sheets of thick and thin Kapton form the flexible substrate on which the conductive elastomer piezoresistors are stencil printed. Excimer laser ablation is used to make the micro-stencil as well as to release the Kapton cantilevers. The fluid-structure interaction is improved by the deposition of a thin film of silicon dioxide, which produces a stress-gradient induced curvature, strongly enhancing the device sensitivity. This new approach also enables the fabrication of backside interconnects, thereby addressing the commonly observed problem of flow intrusion while using conventional interconnection technologies like wire-bonding. Devices with varying dimensions of the sensing element are fabricated and the results presented, with smallest devices having a width of 400 microns and a length of 1.5 mm with flow sensitivities as high as 60 Ohms/m/s. Recommendations are also proposed for further optimization of the device.

The thesis focuses on elastic polymer material that is biodegradable and compatible with human cells and tissues. The presented research describes polymer synthesis, material processing, physico-chemical investigation and biological tests performed on this novel biomaterial.

Regeneration, a spontaneous response of bones in response to injuries, infections and fractures, is severely compromised in certain clinical circumstances. Unfortunately, several shortcomings are associated with the current treatment of bone grafting method such as donor shortage and immune response for allografts and donor morbidity for autografts. Thus, the development of clinical alternates is essential. One promising adjunct method is bone tissue engineering that includes the implantation of a scaffold containing the cells with the supplementation of suitable growth factors. Among the various classes of materials, biodegradable polymers are commonly preferred because their use does not necessitate a secondary surgery for their removal after the intended use. Commercially available polymers such as poly (lactic- co- glycolic acid) and polycaprolactone are expensive and degrade slowly. This motivates the development of novel synthetic biodegradable polymers that are affordable and can be tuned to tailor for specific biomedical applications. The primary aim of this thesis is to synthesize effective biodegradable polymers for drug delivery and bone tissue engineering. The properties of these polymers such as modulus, hydrophobicity and crosslinking etc. were tailored based on the variations in chemical bonds, chain lengths and the molar stoichiometric ratios of the monomers for specific clinical applications. Based on the above variations, degradation and release kinetics were tuned. The cytocompatibilty properties for these polymers were studied and suitable mineralization studies were conducted to determine their potential for bone regeneration.

Die vorliegende Arbeit stellt eine mehrskalige Modellierungs-Strategie für die Beschreibung magnetorheologischer Elastomere (MRE) vor. Diese ermöglicht die Betrachtung von MRE sowohl auf der Mikroskala, wo die heterogene Mikrostruktur bestehend aus Partikeln und Matrix explizit aufgelöst ist, als auch auf der Makroskala, in welcher das MRE als homogener magnetisch aktiver Körper aufzufassen ist. Auf beiden Skalen kommt dabei eine Kontinuumsformulierung des gekoppelten magneto-mechanischen Feldproblems mit Gültigkeit für finite Deformationen zum Einsatz, wobei die Lösung des Systems partieller Differentialgleichungen mittels der Finite-Elemente-Methode erfolgt. Ausgehend von einer experimentellen Charakterisierung der Konstituenten werden Materialmodelle für die elastomere Matrix sowie Carbonyleisen- und Neodym-Eisen-Bor-Partikel formuliert und mittels dieser Daten kalibriert. Im nächsten Schritt erfolgt die Analyse des effektiven Verhaltens hart- und weichmagnetischer MRE auf Basis von numerischen Homogenisierungen verschiedener mikroskopischer Partikelverteilungen und den Materialmodellen für die Konstituenten. Um weiterhin die effiziente Simulation makroskopischer MRE-Proben und -Bauteile zu ermöglichen, ist daran anschließend die Entwicklung und Parametrisierung eines Makromodells ausgehend von mikroskopisch generierten Datensätzen beschrieben. Mit diesem für isotrope, weichmagnetische und elastische MRE gültigen Modell werden abschließend Simulationen des magnetostriktiven sowie des magnetorheologischen Effektes verschiedener Proben durchgeführt. / In this contribution, a strategy for the multiscale modeling of magnetorheological elastomers (MREs) is presented. It allows to consider these materials on the microscopic scale, where the heterogeneous microstructure consisting of an elastomer matrix and embedded magnetizable particles is explicitly resolved, as well as the macroscopic scale, where the MRE is considered to be a homogeneous magneto-active body. On both scales, a continuum formulation of the coupled magneto-mechanical boundary value problem valid for finite strains is applied. The solution of the system of partial differential equations is calculated by using the finite element method. Starting with an experimental characterization of the individual constituents, constitutive models for the elastomer matrix as well as carbonyl iron and neodymium-iron-boron particles are formulated and adjusted to experimental data. In a next step, basic effective properties of magnetically soft and hard MREs are analyzed by using a computational homogenization scheme, where different geometrical arrangements of the particles on the microscale are considered. In order to enable the efficient simulation of macroscopic MRE samples and components, the developement and parametrization of a macroscopic model based on a microscopically generated data basis is described. With this model which is applicable for isotropic, magnetically soft and elastic MREs, simulations of the magnetostrictive and magnetorheological effects of several sample geometries are performed.

In der Dissertation wurden Nanokomposite mit unterschiedlichen Kautschuken (HNBR, EPDM, MAH-g-EPDM) als Basismaterial sowie diversen modifizierten Schichtsilikaten als Füllstoff hergestellt und charakterisiert. Untersucht wurden die sich ausbildenden Strukturen bzw. die Morphologie (Aggregation, mögliche Orientierungen), die mechanischen Eigenschafte (Verstärkungswirkung) sowie die Füllstoff-Füllstoff-Wechselwirkungen und die Polymer-Füllstoff-Wechselwirkungen.

No description available.

Cette thèse s'intéresse au développement de procédés monotopes (en une seule étape) permettant la synthèse accélérée de polymères conducteurs ioniques.Une étude bibliographique sur les poly(liquides ioniques) à base 1,2,3-triazolium (TPILs) a démontré leurs richesses structurale et fonctionnelle inégalées. Leur synthèse requière cependant plusieurs étapes nécessitant l'emploi de catalyseurs, de solvants et d'agents de polymérisation.Une première partie est consacrée au développement d'une voie de synthèse accélérée permettant d'accéder en une seule étape, sans solvant, ni catalyseur à des TPILs de structures variées. Il est en effet aisément possible de moduler les structures chimiques de l'espaceur, du contre-anion et du substituant en position N-3 du groupe 1,2,3-triazolium à partir d'un large choix de monomères a-azoture-?-alcyne et d'agents alkylants.Une seconde partie est consacrée à l'extension de cette voie de synthèse originale à l'élaboration d'une série de réseaux conducteurs ioniques, démontrant ainsi la souplesse du procédé et l'immense possibilité de variation structurale. Ces réseaux possèdent les propriétés uniques des matériaux vitrimères sur la base d'échanges dynamiques des points de réticulation par des réactions de transalkylation des liaisons C-N sous contrainte et température. Ils peuvent ainsi être remis en forme et recyclés sans pertes majeures de leurs propriétés et constituent donc le premier exemple de vitrimère fonctionnel. L'ensemble de ces matériaux de par leurs propriétés ainsi que leur rapidité et leur facilité de synthèse constituent donc une avancée majeure dans le domaine des polymères conducteurs ioniques et leurs applications / This PhD thesis tackles the development of monotopic (or single step) processes enabling the accelerated synthesis of ion conducting polymer materials. A bibliographic study on 1,2,3-triazolium-based poly(ionic liquid)s (TPILs) have demonstrated their unequaled structural and functional richness. However, their syntheses require several synthetic steps and the use of catalysts, solvents and polymerization mediators.A first part is devoted to the development of an accelerated synthetic approach enabling in a single step to access TPILs with broad structural variety without solvent nor catalyst. Indeed the chemical structure of the spacer, the counter-anion and the N-3 substituent of the 1,2,3-triazolium group can be readily tuned from a broad library of a-azide-?-alkyne monomers and alkylating agents.A second part is devoted to the extension of this original synthetic approach to the formation of a series of ion conducting polymer networks, thus demonstrating the flexibility of the process and the broad capacity in structural design. These networks possess the unique properties of vitrimer materials based on dynamic exchanges of the cross-linking points by transalkylation reactions of C-N bonds under strain and temperature. They can thus be reshaped and recycled without significant loss of their properties, which constitute the first example of functional vitrimer.The properties of these materials, as well as the rapidity, the versatility and the flexibility of their syntheses constitute a major breakthrough in the field of ion conducting polymer materials and their applications

No description available.

No description available.

I denna studie undersöks XLANCE® som ett alternativt elastiskt garn emot LYCRA®. Syftet är att jämföra egenskaper och livslängd för att kunna ersätta det etablerade garnet av elastomerer på dagens marknad. Möjligheten till kemisk återvinning och cirkulära resurser har uppvisat vara möjligt med XLANCE®, som är aktuellt för att minimera det textila avfallet av material innehållandes av flera syntetiska fibrer. Genom att konstruera XLANCE® respektive LYCRA® med PES, som huvudmaterial, visar resultateten inga markanta skillnader under ISO-standardiserade tester av elasticitet, draghållfasthet och dimensionsstabilitet både före samt efter 50 tvättar. En ersättning av elastiskt garn kan därför vara möjlig. Slutsatsen bekräftas genom litteraturstudien om att XLANCE® kan separeras ifrån PET genom en filtrering utan att smälta samman, som beskrivs vara utmaningen med spandexfibrer från LYCRA®. XLANCE® höga resistens emot värme och kemikalier möjliggör denna filtrering med glykolsyra och pyrolysoljor som kan användas på nytt. Om framtida forskning kan visa praktiska resultat för separation och kemisk återvinning av XLANCE®, kan detta bli en lösning för att åstadkomma cirkulära modeller efter långvarig användning av elastiska trikåmaterial. / In this study, XLANCE® is investigated as an alternative elastic yarn to LYCRA®. The purpose is to compare properties and longevity to be able to replace the established yarn of elastomers on today’s market. The possibility of chemical recycling and circular resources has been shown to be feasible with XLANCE®, which is relevant to minimizing textile waste of materials containing several synthetic fibers. By constructing XLANCE® and LYCRA® respectively with PES as the main material, the results show no marked differences during ISO standardized tests of elasticity, tensile strength and dimensional stability both before and after 50 washes. A substitution of elastic yarn may therefore be possible. The conclusion confirms through the literature study that XLANCE® can be separated from PET by filtration without fusing, which is described as the challenge with spandex fibers from LYCRA®. XLANCE®’s high resistance to heat and chemicals enables this filtration with glycolic acid, and pyrolysis oils that can be reused. If future research can show practical results for the separation and chemical recycling of XLANCE®, this could become a solution to achieve circular models after long-term use of elastic knitted fabrics.