Dissertations / Theses on the topic 'Macromolecular materials'
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1
Zhang, Borui. "Novel Dynamic Materials Tailored by Macromolecular Engineering." Miami University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1564157701522666.
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Reinsel, Anna Michele. "Spectroscopic Characterization of Organic and Inorganic Macromolecular Materials." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1312823530.
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Eden, E. G. "Analysis of solution-phase macromolecular materials by diffusion NMR." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3006567/.
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Molecules such as covalent cages can adopt several shapes, in which the ratio of starting materials is the same, but the number of starting materials, and the shape of the resulting molecule is different. However, determining this in the absence of a crystal structure can be challenging. Pulsed field gradient (PFG) NMR has been used for two decades to characterise large macromolecules in solution, but it is still difficult to determine precise structural information, because of the rotational-averaging experienced in experimental measurements. Here, we develop experimental techniques for collecting PFG-NMR data that break this barrier, and allow characterisation of several useful molecular descriptors. By measuring the diffusion coefficients of molecules in a range of solvents, incurvate surfaces are probed to map the outer surface of nanometre-sized molecular species. This technique allows details about the geometrical shape of covalent cages to be determined without the need for isolation. Furthermore, we compare experimental PFG-NMR data to structures produced by computational modelling and produce a new molecular descriptor, ρr, which describes the isotropy of covalent cages. This descriptor is used to determine the quality of agreement between proposed structures and experimental PFG-NMR data. In analysing polymers, we develop a new mathematical model for determining the molar-mass dispersity (ÐM) by PFG-NMR. We find a single parameter is sufficient to determine the dispersity of a system, which eliminates the need for data modelling and enhances the reliability of analysis. We hope this will make the technique more accessible to polymer scientists, and will help test the validity of molar-mass dispersity measurements made by other means. Finally, we synthesise five novel dodecaamide cages, which contain functional groups that offer the opportunity to extend functionality beyond the cage via further reaction. We take significant steps towards producing singly functionalised species, which could be incorporated into polymeric materials for the development of robust membranes and coatings.
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Kuttner, Christian [Verfasser]. "Macromolecular Interphases and Interfaces in Composite Materials / Christian Kuttner." München : Verlag Dr. Hut, 2014. http://d-nb.info/1063222036/34.
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Price, Erik Joshua. "EXTREME-ENVIRONMENT PROTECTION USING MACROMOLECULAR COMPOSITE TECHNOLOGY." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1617027732923331.
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Mohin, Jacob W. "Nanostructured π-Electron Materials for Energy Applications Derived from Macromolecular Self-Assembly." Research Showcase @ CMU, 2015. http://repository.cmu.edu/dissertations/1045.
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Globalization and climate change have driven the need to develop new technologies which can provide clean, plentiful energy from renewable sources. This work was focused on the application of nanostructured π-electron materials derived from carbon-based macromolecules towards capturing, converting, and storing energy. Nanostructures are beneficial in this role as they provide high interfacial area and unique electronic properties which can be harnessed to perform chemistry relevant to energy conversion and storage. This work was focused on the characterization, materials development, and device application of two nanostructured systems: (i) poly(3-hexyl)thiophene (P3HT) blended with phenyl(C-61)butyric acid methyl ester (PCBM), and (ii) copolymer-templated nitrogen-doped nanoporous carbons (CTNCs). In both systems, nanomorphology has pronounced impact on the performance of devices made from such materials. P3HT/PCBM blends find application as a photovoltaic material, where the phase-separated morphology is crucial for efficient photogenerated charge collection. Despite widespread recognition of the importance of morphology in P3HT/PCBM photovoltaics, a robust understanding of the unique packing motif of P3HT on the morphology of blended structures has yet to emerge. This thesis addresses this deficiency by developing methods which connects real-space atomic force microscopy images with inverse space x-ray scattering patterns to analyze poorly ordered two-phase systems. The application of this method allowed for quantitative measurement of the phase ratios of P3HT/PCBM nanostructured blends, utilizing the Porod length of inhomogeneity and the Bragg length associated with pseudo-fibrillar P3HT morphologies. The results showed that P3HT possesses void space originating from molecular weight dispersity inherent to polymerization, which accounts for solid-phase solubility of PCBM in P3HT. X-ray scattering and atomic force microscopy were also used in part to characterize CTNCs. Past success using CTNCs as electrocatalysts and supercapacitors motivated research towards increasing their surface area by utilizing a lower molecular weight precursor polymer. Atom-transfer radical polymerization was utilized to synthesize block copolymers consisting of polystyrene and polyacrylonitrile, but it was found their surface areas were lower than those achieved in previous work. Careful structural analysis by variable temperature x-ray scattering showed that crystallization of polyacrylonitrile drives morphological changes on heating, increasing domain spacing. Further thermal analysis showed that polystyrene interferes with the crosslinking of polyacrylonitrile, which may cause morphological collapse leading to low surface area. A feature of CTNCs noted in past and present studies is their sizeable surface area consisting of pores <1 nanometer (micropores). Differential scanning calorimetry showed that reactive chain ends left behind by polymerization might play a role in disrupting the crosslinking process, resulting in a material with sizeable microporosity, which could be used to engineer dual pore-size materials. Finally, CTNCs were utilized for heterogeneous catalytic production of hydrogen from water, with electrons provided by both light and external circuitry. Their performance was correlated with nitrogen heteroatom content, conductivity, and nanomorphology, and shown to match that of noble metals. The lessons learned about nanomorphology in P3HT/PCBM and CTNCs highlight the importance of nanomorphology in energy devices and will serve as insight for materials design in future studies.
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Stimson, Lorna M. "Phase behaviour of macromolecular liquid crystalline materials : computational studies at the molecular level." Thesis, Durham University, 2003. http://etheses.dur.ac.uk/3144/.
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Molecular simulations provide an increasingly useful insight into the static and dynamic characteristics of materials. In this thesis molecular simulations of macro-molecular liquid crystalline materials are reported. The first liquid crystalline material that has been investigated is a side chain liquid crystal polymer (SCLCP). In this study semi-atomistic molecular dynamics simulations have been conducted at a range of temperatures and an aligning potential has been applied to mimic the effect of a magnetic field. In cooling the SCLCP from an isotropic melt, microphase separation was observed yielding a domain structure. The application of a magnetic field to this structure aligns the domains producing a stable smectic mesophase. This is the first study in which mesophases have been observed using an off-lattice model of a SCLCP. The second material that has been investigated is a dendrimer with terminal mesogenic functionalization. Here, a multi-scale approach has been taken with Monte Carlo studies of a single dendrimer molecule in the gas phase at the atomistic level, semi-atomistic molecular dynamics of a single molecule in liquid crystalline solvents and a coarse-grained molecular dynamics study of the dendrimer in the bulk. The coarse-grained model has been developed and parameterized using the results of the atomistic and semi-atomistic work. The single molecule studies showed that the liquid crystalline dendrimer was able to change its structure by conformational changes in the flexible chains that link the mesogenic groups to the core. Structural change was seen under the application of a mean field ordering potential in the gas phase, and in the presence of liquid crystalline solvents. No liquid crystalline phases were observed for the bulk phase studies of the coarse-grained model. However, when the length of the mesogenic units was increased there was some evidence for microphase separation in these systems.
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De, Alwis Watuthanthrige Nethmi Thanurika. "Application of Photochemistry and Dynamic Chemistry in Designing Materials tuned through Macromolecular Architecture." Miami University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=miami1626694956739651.
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Zang, Xu. "Encapsulation of Proteinaceous materials in Macromolecular Organic Matter as a mechanism for environmental preservation /." The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486400446370061.
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Stark, Andreas. "Advancement and optimization of an electrospray injection based in-vacuum patterning system for macromolecular materials." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002534.
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Acosta, Sullcahuamán Julio Arnaldo. "Fractura de materiales poliméricos a altas velocidades de solicitación." Doctoral thesis, Universitat Politècnica de Catalunya, 2001. http://hdl.handle.net/10803/6034.
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Este trabajo se ubica en una perspectiva marcada por dos fuentes de inspiración y exigencia, que se complementan mutuamente: La primera está relacionada con el campo tecnológico y la segunda viene del ambiente científico. Por un lado, es sabido que los productos plásticos y compuestos de matriz polimérica se usan cada vez más en ingeniería y, como la mayoría de los materiales utilizados en este ámbito, muchos están sometidos a cargas dinámicas; de tal manera que en este momento resulte tan necesario el estudio de sus propiedades como el desarrollo de métodos de ensayo fiables para poder caracterizarlos bajo diferentes condiciones de aplicación de carga, siendo de especial interés conocer la respuesta de los mismos a altas velocidades de solicitación. Por otro lado, desde la óptica de la ciencia de los materiales, la relación entre la estructura y el comportamiento de fractura de los polímeros es una de sus más importantes ramas, en la que los ensayos de impacto juegan un rol principal. Cada vez más un conocimiento cuantitativo del comportamiento a impacto, en términos de la ciencia de los materiales, requiere de un conjunto de técnicas adicionales para suplir -teórica y experimentalmente- los métodos de ensayo de impacto básicos especificados por las entidades de normalización. En este sentido, el objetivo central de la presente Tesis es el diseño y puesta a punto de técnicas de ensayo para el estudio de la fractura de los materiales poliméricos, a altas velocidades de solicitación y en el dominio de baja energía.Como resultado y según la orientación del objetivo de la Tesis, se proponen dos metodologías de ensayo de impacto de baja energía: flexión por impacto de baja energía e indentación por impacto. Asimismo, cada metodología incluye el diseño de un "modelo" que permite una aproximación al fenómeno de impacto de baja energía en las geometrías de flexión e indentación respectivamente.
Se ha verificado la validez de los mencionados modelos en el estudio del comportamiento mecánico del polimetilmetacrilato, poliestireno y compuestos de poliestireno y microesferas de vidrio. Las técnicas de impacto de baja energía aplicadas según las metodologías de ensayo propuestas fueron apropiadas y permitieron evaluar la respuesta de estos materiales en el campo elástico, determinar sus características elásticas a elevadas velocidades, así como estimar el inicio del daño en los mismos. Los resultados de estos ensayos, tanto el módulo elástico como las tensiones a las cuales comienzan los fenómenos de emblanquecimiento, crazing y rotura, fueron interpretados según los modelos propuestos. Finalmente, por extensión, las metodologías y modelos propuestos son válidos y apropiados para el estudio de los plásticos, cuando menos similares a los estudiados.
Este trabajo se ha estructurado en concordancia con la metodología utilizada en la investigación correspondiente. Así, en el primer capítulo se ha hecho una revisión sobre los temas afines a la tesis, desde sus aspectos conceptuales hasta los más avanzados; para examinar la evolución y el estado actual del tema en cuestión y precisar los conocimientos que sirvan de base a esta investigación. En el segundo capítulo se describen las características generales y particulares de los materiales sometidos a estudio experimental. En el tercer capítulo se exponen los métodos de ensayo utilizados y las herramientas experimentales necesarias para su realización.
Finalmente, antes de exponer las conclusiones, fue de rigor abordar un cuarto capítulo referido a la flexión por impacto de baja energía y otro quinto capítulo similar que versa sobre la indentación por impacto, para la presentación, interpretación y análisis de resultados, así como la correspondiente discusión.
This work is situated in a perspective highlighted by two inputs of inspiration and exigency, that complement each other: the first input is related with the technology field, and the second comes from a scientific field. On one hand, it is known that plastic products and composites of polymeric matrix are used increasingly in the engineering industry, and as many of the materials used in this field, they are usually exposed to dynamic charges.
Therefore, it is necessary the study of their properties like the development of methods and tests to be able to characterize them under different conditions of charge applications, being of special interest to know the results at high speeds. On the other hand, from the material science point of view, the relation between the structure and the behavior of fracture of the polymers is one of the most important subjects, in which the impact tests play a fundamental role. The knowledge of fracture behavior, in terms of science of the materials, requires a group of additional techniques in order to supply (theoretically and experimentally) the basic impact test methods specified by the normalization entities. In this sense, the principal objective of this thesis is the design and development of test techniques for the study of the fracture of polymers at high speeds of solicitation and in the domain of low energy.
As a result and based in the objective of this thesis, it is proposed two methods of test for impact of low energy: flexion by impact of low energy and indentation by impact. In the same way, every methodology includes the design of a "model" that allows an approximation for the phenomenon of impact of low energy in the geometric of flexion and indentation, respectively. The validity of the models mentioned above in the study of the mechanic behavior of the polymethylmetacrilate, polystyrene and polystyrene filled with different percentages of glass beads has been verified. The techniques for impact of low energy applied according to the methodology of proposed test were appropriate and allowed to evaluate the response of these materials in the elastic field, to determine its elastic characteristics at high speeds, and to estimate the initial damage of components. The results of these tests, likewise the elastic module and the tensions at which begin the whitening phenomena, crazing and rupture, where interpreted according to the proposed models.
Finally, per extension, the methodology and proposed methods are valid and appropriate for the study of plastics, at least similar to the ones studied.
This work has been structured in accordance with the methodology utilized in the correspondent investigation. Thus, in the first chapter, a revision of the subjects corresponding to the thesis were made, from its conceptual aspects to the more advanced, in order to examine the evolution and estate of the actual subject in question and precise the knowledge that can be use as a base for this investigation. In the second chapter, the general and particular characteristics of the materials submitted to the experimental studies are described. In the third chapter the methods of test utilized and the necessary experimental tools for its realization are exposed.
Finally, before the conclusions are presented, it was consistent to add a fourth chapter that refers to the flexion by impact, and another fifth chapter similar that contains the indentation by impact for the presentation, interpretation and analysis of results, and the related discussion.
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Lenart, William R. "EXPANDING EXPERIMENTAL AND ANALYTICAL TECHNIQUES FOR THE CHARACTERIZATION OF MACROMOLECULAR STRUCTURES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1584358701735061.
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Carrillo, Navarrete Fernando. "Caracterización estructural de fibras lyocell y su comportamiento frente a procesos de degradación." Doctoral thesis, Universitat Politècnica de Catalunya, 2002. http://hdl.handle.net/10803/6428.
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Durante estas últimas décadas ha habido un gran interés científico y tecnológico en el desarrollo de nuevos sistemas para la obtención e hilatura de fibras de celulosa regenerada. Las tecnologías aplicadas en este campo no sólo deben satisfacer los requisitos económicos sino que además deben cumplir con los modernos estándares medioambientales. Actualmente, sólo el proceso NMMO, basado en el uso del disolvente N-óxido de N-metilmorfolina hidratado, ofrece una alternativa comercialmente viable entre los diferentes métodos existentes de producción de fibras de celulosa regenerada a partir de disolventes orgánicos. El producto obtenido ha aparecido en el mercado con el nombre genérico de lyocell (CLY), ofreciendo, sobre la fibra viscosa, un proceso de producción más sencillo y respetuoso con el medio ambiente.Debido a la reciente aparición de las fibras de lyocell en el mercado, se han suscitado una serie de incógnitas respecto tanto de su estructura como de su comportamiento en las condiciones de trabajo y/o utilización. Por esta razón, el objetivo del presente trabajo es el de contribuir a un mejor conocimiento sobre su estructura y evaluar su comportamiento frente a la acción de diversos tratamientos: absorción de colorantes, acción enzimática y fibrilación.
En el capítulo II, se ha realizado la caracterización estructural de la fibra de lyocell, mediante las técnicas de espectroscopía infrarroja por transformada de Fourier (FT-IR) y análisis térmico por calorimetría diferencial (DSC) y termogravimetría (TG). Las bandas de absorción FT-IR indican que la fibra de lyocell está formada principalmente por celulosa cristalizada II y celulosa amorfa y que la fibra de lyocell presenta mayor cristalinidad que las fibras de celulosa regenerada tradicionales. Por otra parte, el análisis térmico demuestra que la fibra de lyocell es térmicamente más estable que la fibras de celulosa regenerada obtenidas por el proceso tradicional del xantato de celulosa.
En el capítulo III, se ha caracterizado la influencia de la estructura de la fibra en el rendimiento de absorción del colorante directo C.I. direct blue 1, mediante el estudio de las isotermas de equilibrio, estimándose el valor del volumen libre característico de la fibra lyocell. También se han calculado las magnitudes termodinámicas que gobiernan el proceso de absorción. Los resultados indican que la fibra de lyocell presenta una menor estabilidad de los enlaces colorante/fibra que las fibras de celulosa regenerada tradicionales, como consecuencia de su mayor cristalinidad. Además, se ha desarrollado un modelo de absorción que reproduce los resultados experimentales satisfactoriamente.
Por otra parte, en el capítulo IV, se han determinado las cinéticas de hidrólisis enzimática con celulasas de las fibras de lyocell. A partir de estos resultados se han calculado los parámetros cinéticos característicos de la hidrólisis, comparándolos con los obtenidos para las fibras de modal y viscosa de referencia. Del estudio se destaca la menor velocidad de hidrólisis obtenida para las fibras de lyocell, lo que constata la presencia de una estructura de celulosa menos degradable.
Finalmente, en el capítulo V, se ha evaluado la influencia de los tratamientos industriales de fibrilación y desfibrilación enzimáticos en las propiedades mecánicas (curvas carga/alargamiento), morfológicas (microscopía electrónica), estructurales (FT-IR), de accesibilidad (absorción de colorantes) y reactividad (hidrólisis enzimática). El tratamiento de fibrilación produce una extensa fibrilación sobre la superficie de las fibras, mientras que un gran número de estas fibrillas son eliminadas posteriormente durante la etapa de desfibrilación enzimática. Ambos tratamientos disminuyen significativamente las propiedades de resistencia mecánica, aunque en el tratamiento con enzimas la reducción es más intensa debido a la especificidad de la hidrólisis catalítica. Los tratamientos mejoran la accesibilidad y reactividad del sustrato, debido al incremento de la superficie específica de la fibra provocado durante la fibrilación, aunque los resultados indican que se produce una descristalización de la estructura por transformación de la celulosa cristalizada II a celulosa amorfa.
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Castiglione, Andrea. "Liquid crystalline macromolecular architectures based on regioregular poly(3-alkylthiophene) as backbone and calamitic mesogens as side-groups : towards ambipolar materials." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066693.
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Très récemment, le potentiel des semi-conducteur organiques (OSC) ambipolaires à attiré l'attention par de nombreuses applications technologiques. Dans le domaine de la microélectronique organique, l'un des obstacles majeurs pour le développent des OSC est le design de systèmes capables de transporter à la fois les électrons et les trous. Les matériaux semi-conducteurs ambipolaires ordonnés, peuvent répondre à cette problématique. Dans ce contexte nous avons développé la synthèse et la caractérisation d'une architecture macromoléculaire originale, fondée sur l'association d'un polymère semi-conducteur régiorégulier d'une part, avec des molécules ?-conjuguées cristal liquides ayant la propriété de s'auto-organiser spontanément d'autre part. Afin d'améliorer les propriétés mésomorphes et électroniques de ce système macromoléculaire, une gamme de composés différant par (i) la nature chimique du groupement pendant et (ii) le dégrée de polymérisation moyen du polymère à été synthétisée. La présence d'une mesophase a été confirmée pour chacun de ces composés par diffraction des rayons X et une mesophase de type lamello-lamellaire, présentant une alternance de couches électron-donneur ou électron-accepter à également pu être mis en évidenceVery recently ambipolar organic semi-conductors (OSC) have gaining attention for their potential use in numerous technologically relevant applications. Representative technological examples are the area of organic microelectronics where patterning of p- and n-channel semiconductors is one of the major hurdles for the implantation of OSC in organic complementary logic circuit. To achieve this objective, well-ordered ambipolar semiconducting materials are needed. In this work we investigated the self-organization and the electronic properties of a series of side chain liquid crystal (SCLC) semiconducting polymers where: (i) the backbone is a π-conjugated polymer and (ii) the side-groups are π-conjugated calamitic mesogens. We present our results on the design, synthesis, and structural characterization of this new liquid crystal regioregular poly(3-alkylthiophene) polymer family post-functionalized with side-on calamitic moieties. The parameters of these materials are: (i) the chemical nature of the side-group moieties and (ii) the degree of polymerization. As a result we will show that this strategy leads to the supramolecular self-assembly of this SCLC semiconducting polymer in a peculiar lamello-lamellar mesophase, where the two different lamellas present two different electronic properties, such as electron donor and electron acceptor behaviors
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Etok, S. E. "Structural characterisation and in vitro behaviour of apatite coatings and powders." Thesis, Faculty of Medicine and Biosciences, 2009. http://hdl.handle.net/1826/3973.
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Hydroxyapatite (HAP) coatings are used in orthopaedic surgery for bone regeneration.
Current methods of phase quantification of HAP coatings suffer from drawbacks. A
novel methodology of quantitative phase analysis of HAP coatings has been devised and
validated. This method, based on whole pattern fitting with a fundamental parameters
approach, incorporates amorphous calcium phosphate (ACP) and apatite phases into
structural refinements.
A comparison of the structural and chemical properties of plasma sprayed (PS) and novel
electrodeposited (ED) HAP coatings has been conducted. ED coatings contained less
ACP and more preferred orientation than the PS coatings, although the stoichiometry was
similar.
In vitro investigations of PS and ED coatings in simulated body fluid and foetal calf
serum revealed that both are bioactive. A carbonated apatite layer produced on the ED
coatings was -0.7μm thick with a stoichiometry and chemical constituents similar to that
of natural bone apatite.
PS coatings produced a nanocrystalline carbonated apatite layer (-4μm). For the first
time it has been possible to model crystalline HAP and nanocrystalline apatite as
independent phases and obtain accurate lattice parameters for each.
A positive linear correlation has been made between microstrain and the solubility of
HAP and carbonated apatites. Dissolution studies have shown that the behaviour of HAP
and carbonated apatite is dominated by crystallite size at low undersaturation and by
crystallite size and microstrain at high undersaturation for crystallites between -30OA-
1000A. Metastable equilibrium occurred for crystallites <_400A at low undersaturation.
Carbonate content did not affect the solubility or dissolution behaviour.
A novel technology for coating polymeric tape with HAP for potential use in anterior
cruciate ligament reconstruction has been devised. Mechanical tests have demonstrated
that no adverse properties are induced by the coating technology. Cell culture studies
have shown that the HAP layer is capable of enhanced attachment, proliferation and
differentiation of osteoblast cells compared to uncoated tape.
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Etok, Susan Essien. "Structural characterisation and in vitro behaviour of apatite coatings and powders." Thesis, Cranfield University, 2005. http://dspace.lib.cranfield.ac.uk/handle/1826/3973.
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Hydroxyapatite (HAP) coatings are used in orthopaedic surgery for bone regeneration. Current methods of phase quantification of HAP coatings suffer from drawbacks. A novel methodology of quantitative phase analysis of HAP coatings has been devised and validated. This method, based on whole pattern fitting with a fundamental parameters approach, incorporates amorphous calcium phosphate (ACP) and apatite phases into structural refinements. A comparison of the structural and chemical properties of plasma sprayed (PS) and novel electrodeposited (ED) HAP coatings has been conducted. ED coatings contained less ACP and more preferred orientation than the PS coatings, although the stoichiometry was similar. In vitro investigations of PS and ED coatings in simulated body fluid and foetal calf serum revealed that both are bioactive. A carbonated apatite layer produced on the ED coatings was -0.7μm thick with a stoichiometry and chemical constituents similar to that of natural bone apatite. PS coatings produced a nanocrystalline carbonated apatite layer (-4μm). For the first time it has been possible to model crystalline HAP and nanocrystalline apatite as independent phases and obtain accurate lattice parameters for each. A positive linear correlation has been made between microstrain and the solubility of HAP and carbonated apatites. Dissolution studies have shown that the behaviour of HAP and carbonated apatite is dominated by crystallite size at low undersaturation and by crystallite size and microstrain at high undersaturation for crystallites between -30OA- 1000A. Metastable equilibrium occurred for crystallites <_400A at low undersaturation. Carbonate content did not affect the solubility or dissolution behaviour. A novel technology for coating polymeric tape with HAP for potential use in anterior cruciate ligament reconstruction has been devised. Mechanical tests have demonstrated that no adverse properties are induced by the coating technology. Cell culture studies have shown that the HAP layer is capable of enhanced attachment, proliferation and differentiation of osteoblast cells compared to uncoated tape.
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Sandouk-Lincke, Nadia Anna Al [Verfasser]. "Application of advanced pyrolysis for the analysis of biogeochemically and environmentally significant macromolecular organic materials : microfossils, macerals and drilling fluid additives / Nadia Anna Al Sandouk-Lincke." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2015. http://d-nb.info/1073885941/34.
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Xiao, Yiming. "Engineering, Synthesis and Characterization of New - π Conjugated (Macro)molecular Architectures for Organic Optoelectronics : application toward ambipolar materials." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066638/document.
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Dans le domaine de l’électronique organique comprenant les cellules photovoltaïques (OPV), les diodes électroluminescentes (OLED) et les transistors à effet de champ (OFET), l’intérêt pour des matériaux ambipolaires a fortement augmenté au cours de ces dernières années.Dans ce contexte, nous nous sommes intéressés au cours de cette thèse au design et à la préparation de différentes architectures semi-conductrices auto-organisées avec lesquelles il serait possible d’injecter et de transporter à la fois les trous et les électrons. Notre approche est basée sur des matériaux cristaux liquide (LC) incorporant différents types de systèmes électron-donneurs (p-type) ou électron-accepteurs (n-type) dans une architecture moléculaire ou macromoléculaire unique. Ainsi, nous avons synthétisé et caractérisé différentes séries de semi-conducteurs organiques tels que des diades discotiques LC donneur-σ-accepteur, des diades calamitiques LC donneur-σ-accepteur, et des polymères en peigne LC donneur-σ-accepteur portant des groupements latéraux discotiques. Leurs comportement thermiques, leurs propriétés optiques et électroniques, leurs propriétés d’auto-organisation en volume et en film mince, ainsi que leurs propriétés de transport de charge sont présentées et discutés.Ces études ont montré que tous ces matériaux présentent des propriétés liquide-cristallines en s’auto-organisant selon différentes structures telles que des organisations colonnaires, lamellaires et lamello-colonnaires. Plus particulièrement, ces matériaux montrent une nano-ségrégation spontanée en volume des fragments de type p et de type n, formant des chemins bien distincts pour chaque type de porteurs de charge, ces résultats étant bien mis en évidence par les premières mesures de transport de charge ambipolaire observées par temps de vol et en configuration transistor à effet de champsIn the general field of organic electronics, including Organic Photovoltaic (OPV), Organic Light-Emitting Diode (OLED) and Organic Field-Effect Transistor (OFET), the interest for the ambipolar organic materials have increased remarkably during the recent years.In this context, we were interested, in this present work, in designing and preparing different new self-organized semiconducting architectures in which it could be possible to inject and transport both holes and electrons. Our approach is based on liquid crystalline (LC) materials incorporating different kinds of electron-donor (p-type) and electron acceptor (n-type) π-conjugated systems in a unique molecular or macromolecular architecture. Thus, we synthesized and characterized different series of organic semiconductors such as donor-σ-acceptor discotic LC dyads and triads, donor-σ-acceptor calamitic LC dyads, and donor-σ-acceptor side-chain LC polymers bearing discotic side-groups. Their thermal behaviors, optical and electronic properties, self-organization properties both in bulk and in thin films, and finally charge transport properties are presented and discussed.Based on different characterization techniques, we demonstrated that all these series of materials present liquid crystalline properties in self-organizing in different structure such as columnar, lamellar, and lamella-columnar organizations. More particularly, these materials exhibit spontaneous nanosegregation of p-type and n-type entities in bulk, leading to well defined distinct conductive channels for each type of charge carriers as evidenced by the preliminary ambipolar charge transport properties observed by Time-of-flight and Field effect transistor measurements
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Shebani, Anour N. "The effect of wood composition and compatibilisers on polyethylene/wood fibre composites." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5270.
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Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: The effects of the macromolecular composition and content of different wood species on the properties of wood-polymer composites (WPCs) achieved when using poly(vinyl alcohol-co-ethylene) (EVOH) as a compatibiliser and linear low density polyethylene (LLDPE) as a matrix, were investigated. Four wood different species (A. cyclops (acacia), E. grandis (eucalyptus), P. radiata (pine) and Q. alba (oak)) with different macromolecular composition and contents and average particle lengths were used. WPCs filled with these species and WPCs filled with the same species but without extractives were prepared using 10% wood content and different amounts (0, 2, 5, 7 and 10%) of EVOH. An EVOH content of 7% was found to be optimum. Unextracted woods produced WPCs with higher mechanical properties and better resistance to ultraviolet (UV) degradation, while the extracted woods produced WPCs with lower water absorption (WA) rates and better thermal stability. Use of unextracted A. cyclops resulted in composites with superior mechanical and thermal properties compared with the other unextracted species, most probably due to its higher cellulose and lignin contents and a favourable average wood particle length (0.225 mm). A. cyclops composites also had higher WA and thickness swelling (TS) rates most likely due to the greater number of free hydroxyl groups present in these composites because of higher cellulose content. Composites containing wood species with a high lignin and extractive content, such as A. cyclops and Q. alba, exhibited higher resistance to UV degradation. Poly(vinyl alcohol-co-ethylenes) (EVOHs) with different ethylene content (27, 32, 38 and 44%) and A. cyclops with different particle sizes (180, 250 and 450 ìm) were used to prepare WPCs with 10% A. cyclops content. The effect of the contact area between the A. cyclops particles and LLDPE achieved when using EVOHs as compatibilisers on the properties of WPCs was also investigated. The greatest improvements in the mechanical and thermal properties of composites made with A. cyclops with particle size 180 ìm were obtained when EVOH with 44% ethylene content was used. The greatest improvements in the composites made with A. cyclops with particle size 250 ìm were achieved when EVOH with 38% ethylene content was used. Composites made with A. cyclops with particle size 450 ìm exhibited better properties when EVOH with 27% ethylene content was used. All the composites that had better mechanical and thermal properties, also exhibited better compatibility and interface adhesion. Two successful approaches were used to impart more attractive ecological and economical advantages to WPCs. In the first approach, (0, 2, 5 and 7%) degraded LLDPE was used as a compatibiliser in WPCs at levels of 10, 30 and 50% wood content. The resulting mechanical properties, such as tensile strength and hardness, thermal and morphological properties of the compatibilised composites were slightly higher than those of noncompatibilised composites and virgin LLDPE. Elongation at break and impact properties of the compatibilised composites were lower than in virgin LLDPE, but higher than in noncompatibilised composites. In the second approach, polyethylene (PE) and various functionalised polyethylenes (PEs) were synthesised by copolymerising ethylene and 10-undecen-1-ol using a soluble metallocene/methylaluminoxane catalyst at room temperature. The incorporation of functional groups increased with increasing comonomer content. WPCs with 10 and 30% wood content were prepared. The composites prepared with functionalised PEs had better mechanical, thermal and morphogical properties than the composites prepared with PE. Composites made with functionalised PE with higher hydroxyl groups content exhibited better properties than composites made with functionalised PE with lower hydroxyl groups content. Composites with 10% wood content exhibited better properties and performance than composites with 30% wood content.
AFRIKAANSE OPSOMMING: Die gevolg van die makromolekulere samestelling van verskillende houtspesies op die eienskappe van hout-polimeer saamgestelde materiale (HPS) wanneer poli(viniel alcohol-ko-etileen) (EVOH) as versoeningsmiddel gebruik word saam met linieere lae digtheid poli(etileen) (LLDPE) as matriks is ondersoek. Vier houtspesies (A. cyclops (acacia), E. grandis (eucalyptus), P. radiata (pine) and Q. alba (oak)) met verskillende makromolekulere samestelling and partikelgrootte-verspreiding is gebruik in die studie. HPS materiale is berei met hierdie vesels, beide voor en na ekstraksie van die houtpartikels met onderskeidelik warm water en oplosmiddels (alleen en in kombinasie). In hierdie HPS materiale is 10% hout gebruik en 0, 2, 5, 7 en 10% EVOH. 'n EVOH inhoud van 7% is as optimum bepaal. Houtpartikels voor ekstraksie het HPS materiale met beter meganiese eienskappe en beter weerstand teen UV bestraling, terwyle partikels wat ekstraksie ondergaan het HPS materiale met laer water-absorpsie en beter hitte-stabiliteit to gevolg gehad het. Die gebruik van ongeekstraheerde A. cyclops het samegestelde materiale met die beste meganiese en termiese eienskappe tot gevolg gehad in vergelyking met die ander houtspesies (voor ekstraksie), as gevolg van die hoer sellulose en lignien inhoud van die spesie, sowel as 'n voordelige partikelgrootte-verspreiding. A. Cyclops saamgestelde materiale he took hoer waterabsorpsie (WA) en dikte-swelling (DS) tempos gehad, weens die groter hoeveelheid vrye hidroksielgroepe teenwoording in die materiale, direk in verwantskap met die sellulose-inhoud. Saamgestelde materiale met 'n hoe hoevellheid lignien en ekstraheerbare materiale (A. cyclops and Q. alba) het beter weerstand teen UV-degradasie geopenbaar. Verskillende poli(viniel alkohol-ko-etileen) polimere (EVOHs) met wisselende etileen-inhoud (27, 32, 38 en 44%) en A. Cyclops met verskillende partikel-groottes (180, 250 en 250 µm) is gebruik om HPS materiale met 10% hout te vervaardig. Die gevolg van die kontak-area tussen die houtpartikels en die LLDPE wanneer EVOHs as versoeningsmiddel gebruik is, is ook ondersoek. Die beste verbetering in die meganiese en termiese eienskappe van die saamgestelde materiale met A. cyclops met partikel-grootte 180 µm is gekry met EVOH met 44% etileen-inhoud, terwyl die beste resultate met 250 µm partikels verkry is met 'n EVOH met 38% etileen, en met 27% etileen in die geval van die 450 µm partikels. Twee benaderinge om meer aantreklike ekologiese en ekonomiese eienskappe by die HPS materiale te bewerkstellig was suksesvol. In die eerste geval is gedegradeerde LLDPE as versoeningsmiddel gebruik. Die resulterende meganiese eienskappe van die HPS materiale met LLDPE as versoeningsmiddel was beter as die HPS mateirale daarsonder. Samegestelde materiale met 10, 30 en 50% hout is vervaardig. Die trekverlenging by die breekpunt sowel as die impaksterkte van die HPS materiale was laer as LLDPE alleen, maar beter as die nie-versoende HPS materiale. In die tweede benadering is polietileen (PE) en gefunksionaliseerde PE gesintetiseer deur etileen en 10-undekeen-1-ol te koplimeriseer met ‘n oplosbare metalloseen/metiel alumoksaan katalis. Die hoeveelheid funskionele (OH) groepe is verhoog deur toenemend ekomonommer-inhoud. HPS materiale met 10 en 30% hout is vervaardig. Die saamgestelde materiale met funksionele PE het beter maganiese eienskappe gehad as die met gewone PE. Hoe hoër die hidroksielgroep-inhoud, hoe beter die eienskappe van die HPS materiale, terwyl die materiale met 10% hout beter eienskappe openbaar het as materiale met 30% hout.
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Menzel, Jan Philipp. "Wavelength-dependent photoreactivity for macromolecular material design." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/210196/1/Jan%20Philipp_Menzel_Thesis.pdf.
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This thesis is a study of light-induced chemical reactions and the dependence of their reactivity and selectivity on the wavelength of light. Both experimental methods using tunable laser systems and light emitting diodes as well as computational simulation methods are developed that establish an understanding of light-induced bond-forming reactions. Information on wavelength-dependent reactivity is used to predict the rate of LED light induced reactions. The design of systems with chemical reaction pathways that are fully controllable by the wavelength of light paves the way to advanced 3D micro- and nano-printing of macromolecular materials through direct laser writing.
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Nolan, Christine Marie. "Microgel Based Materials for Controlled Macromolecule Delivery." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6874.
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This dissertation focuses on utilization of poly(N-isopropylacylamide) (pNIPAm) based mirogels for regulated macromolecule drug delivery applications. There is particular emphasis on incorporation of stimuli responsive materials into multi-layer thin film constructs with the main goal being fabrication of highly functional materials with tunable release characteristics. Chapter 1 gives a broad overview of hydrogel and microgel materials focusing on fundamental properties of pNIPAm derived materials. Chapter 2 illustrates the progression of controlled macromolecule release from hydrogel and microgel materials and sets up the scope of this thesis work. Chapter 3 details studies on thermally modulated insulin release from microgel thin films where extended pulsatile release capabilities are shown. Chapters 4 and 5 focus on more fundamental synthesis and characterization studies of PEG and acrylic acid modified pNIPAm microgels that could ultimately lead to the design of protein loaded microgel films with tunable release characteristics. Chapter 6 illustrates fundamental macromolecule loading strategies, which could also prove useful in future protein drug delivery design using stimuli responsive networks. Chapter 7 concentrates on direct insulin release studies that probe the interaction between entrapped and freely diffusing protein and microgels. These model experiments could prove useful in design of tunable macromolecule drug release from functionally modified microgels and could aid in the tailored design of peptide-loaded microgel thin films. Chapter 8 discusses the future outlook of controlled macromolecule release from microgel based materials.
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Lis, Arias Manuel J. (Manuel José). "Comportamiento cinético de fibras Tencell con colorantes directos." Doctoral thesis, Universitat Politècnica de Catalunya, 2002. http://hdl.handle.net/10803/6490.
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Objetivos de la Tesis:El objetivo principal de la presente Tesis, Cinética de Tintura de Tencel ,se centra en dos objetivos parciales: la sensibilidad a la temperatura y el efecto de la variación de la concentración de electrolito en la misma.
La evaluación cinética del sistema fibra-colorante, se ha realizado mediante la evolución de la expresión Ct/Cinf, relación entre colorante absorbido por la fibra en un tiempo t y la concentración del mismo en el equilibrio, en función de los distintos parámetros estudiados a través del análisis de varios modelos.
Metodología empleada
La aproximación a dicha evaluación puede realizarse mediante: Modelos cinéticos semi-empíricos y Modelos matemáticos provenientes de la segunda ley de Fick. En los primeros, es la constante cinética k el parámetro definitorio del proceso, mientras que, en los modelos matemáticos es el adimensional Dt/r2.
Ambos enfoques describen la evolución del mismo fenómeno y, por lo que debería existir algún tipo de relación entre k y Dt/r2. El estudio del proceso desde ambos puntos de vista y, cuando sea posible, establecer la relación mencionada, es otro de los objetivos de la Tesis. Con ello, se podrá comparar la incidencia estructural del sustrato respecto al comportamiento cinético.
Fases del trabajo
Siendo Tencel una fibra celulósica, se ha realizado un análisis comparativo con Viscosa , mediante un estudio experimental en celda de tintura en flujo continuo con medición espectrofotométrica on line .
Las condiciones experimentales escogidas han sido: Temperaturas de 30, 40, 50, 60, 70 y 80ºC y [NaCl] de 0.5, 1.0 y 1.5 g/L, valorando la cantidad de colorante que la fibra absorbe, en función del tiempo.
Conclusiones y valoración de los resultados obtenidos
La comparación de D/r2 entre ambas fibras indica que:
Exceptuando el modelo de Chrastil, los valores de D/r2 obtenidos, disminuyen con el aumento de la concentración de electrolito .
Los valores obtenidos a partir de la aproximación de Crank y de la de Rais-Militky presentan gran similitud.
Hay un estrecho paralelismo entre los valores obtenidos a partir de la ecuación de Cegarra-Puente-Valldeperas y los de las aproximaciones matemáticas de Crank y Rais-Militky.
Para algunos modelos matemáticos, a la concentración máxima de electrolito, los valores de D/r2 son muy similares en Viscosa y prácticamente coincidentes en Tencel.
El orden de magnitud de los Dap para Tencel pueden apreciarse en la Tabla siguiente.
Dap (cm2/s) Modelo
10-11-10-14 Cegarra-Puente-Valleperas
10-12-10-14 Chrastil
10-11-10-16 Urbanik
10-11-10-14 Crank
10-11-10-14 Rais-Militky
10-13-10-16 Kilby
A pesar de las diferencias según la ecuación considerada, existe en Tencel una variación del Dap en función de los tres niveles de agotamiento en los que se ha estructurado el estudio cinético.
A través de la cinética de tintura se ha podido demostrar la existencia de varias capas de distinto nivel de ordenación microestructural que implicará, la necesidad de reconsiderar los procesos de tintura a fin de obtener unos niveles de penetración del colorante en la fibra similares a los de otras fibras celulósicas, al existir en Tencel velocidades de difusión diferenciadas en sus distintas capas.
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Filion, Potts Tera M. "Biomimetic Synthetic Tissue Scaffolds for Bone Regeneration: A Dissertation." eScholarship@UMMS, 2011. https://escholarship.umassmed.edu/gsbs_diss/556.
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Injury to bone is one of the most prevalent and costly medical conditions. Clinical treatment of volumetric bone loss or hard-to-heal bony lesions often requires the use of proper bone grafting materials, with or without adjuvant anabolic therapeutics. Despite significant problems associated with autografting (donor site morbidity, limited supplies) and allografting (disease transmissions, high graft failure rates) procedures, synthetic bone grafts remain the least utilized clinically. Existing synthetic orthopaedic biomaterials rarely possess a combination of bone-like structural and biochemical properties required for robust osteointegration, scalable and user-friendly characteristics indispensable for successful clinical translations. This thesis tests the hypothesis that by recapitulating key structural elements and biochemical components of bone in 3- and 2-dimensional biomaterials, scalable synthetic bone grafts can be designed to enable expedited healing of hard-to-heal volumetric bone loss. Specifically, FlexBone, a 3-dimensional hydrogel scaffold encapsulating 50 wt% of structurally well integrated nanocrylstalline hydroxyapatite, the main inorganic component of bone, was developed. The large surface area of nanocrystalline hydroxyapatite combined with its intrinsic affinity to proteins and its excellent structural integration with the hydrogel matrix enabled FlexBone to both sequester endogenous protein signals upon press-fitting into an area of skeletal defect and to deliver exogenous protein therapeutics in a localized and sustained manner. We demonstrated that FlexBone enabled the functional healing of critical-size long bone defects in rats in 8 – 12 weeks with the addition of a very low dose of osteogenic growth factor BMP-2/7. This promising synthetic bone graft is now being explored for the delivery of multiple growth factors to expedite the healing of diabetic bony lesions. In addition, a 2-dimensional electrospun cellulose fibrous mesh was chemically modified with sulfate residues to mimic sulfated polysaccharide ECM components of skeletal tissues to enabled progenitor cell attachment and differentiation as well as controlled retention and localized/sustained delivery of protein therapeutics. This sulfated fibrous mesh is currently explored as synthetic periosteum to augment the osteointegration of devitalized structural allografts. Finally, a rat subcutaneous implantation model developed to examine the biocompatibility of newly developed biodegradable shape memory polymer bone substitutes is also presented.
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Ferrer, Balas Dídac. "Aplicación del método del trabajo esencial de fractura al estudio de films de polipropileno y de copolímeros propileno-etileno en bloques." Doctoral thesis, Universitat Politècnica de Catalunya, 2001. http://hdl.handle.net/10803/6033.
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En aquest treball, es presenta l'estudi de les propietats de fractura de films de polipropilè (PP) i copolímers etilè-propilè en blocs (EPBC) per mitjà de la tècnica del Treball Essencial de Fractura (EWF). Aquesta tècnica es mostra com una alternativa molt adapatada per a l'aplicació de la Mecànica de la Fractura a films dúctils, i permet separar l'energia total de fractura en un terme essencial, que fa referència al treball real de fractura, i un terme no essencial, relatiu a la dissipació d'energia de deformació plàstica al voltant del camí de fractura.En una primera part, s'estudien les condicions òptimes d'assaig de la técnica EWF per aplicar-la a films de polímers dúctils, analitzant la influència de variables d'assaig com són les dimensions de la proveta, la velocitat d'assaig o el mode de fractura.
En una segona part, s'ha estudiat la relació entre els paràmetres de fractura obtinguts mitjançant la tècnica EWF i diferents propietats referents a l'estructura del material. Entre aquestes, s'ha analitzat la influència de les característiques cristal·lines, modificades per un procés de recuit previ als assajos, i del contingut d'etilè a diferents temperatures d'assaig. S'han aplicat nombroses tècniques de caracterització tant mecàniques i de fractura com físico-químiques.
Els resultats mostren que el mètode EWF s'adapta bé a la necessitat de caracteritzar la fractura de films polimèrics, i permet estudiar la relació entre la seva estructura i les propietats de fractura que presenten. Alhora, es plantegen diferents modificacions del mètode que permeten potenciar les seves possibilitats. S'observa que al millorar la perfecció cristalina dels materials estudiats, el terme essencial augmenta en detriment del terme no essencial. També es demostra que la presència d'etilè en els EPBC minimitza la gran dependència que presenten les propietats de fractura del PP homopolímer en variar la temperatura, i es relaciona aquest comportament amb els canvis dels mecanismes de deformació predominants en el material.
En este trabajo, se presenta el estudio de las propiedades de fractura de films de polipropileno (PP) y copolímeros etileno-propileno (EPBC) por medio de la técnica del Trabajo Esencial de Fractura (EWF). Esta técnica se muestra como una alternativa muy adaptada para la aplicación de la Mecánica de la Fractura en films dúctiles, y permite separar la energía total de fractura en un término esencial, que hace referencia al trabajo real de fractura, y un término no esencial, relativo a la disipación de energía de deformación plástica alrededor del camino de fractura.
En una primera parte, se estudian las condiciones óptimas de ensayo de la técnica WF para aplicarla a films de polímeros dúctiles, estudiando la influencia de variables de ensayo como son las dimensiones de probeta, la velocidad de ensayo o el modo de fractura.
En una segunda parte, se ha estudiado la relación entre los parámetros de fractura obtenidos mediante la técnica EWF y distintas propiedades referentes a la estructura del material. Entre éstas, se ha analizado la influencia de las características cristalinas, modificadas por un proceso de recocido previo a los ensayos, y del contenido de etileno a diferentes temperaturas de ensayo. Se han aplicado numerosas técnicas de caracterización, tanto mecánicas y de fractura como físico-químicas.
Los resultados muestran que el método EWF se adapta bien a la necesidad de caracterizar la fractura de films poliméricos, y permite estudiar la relación entre su estructura y las propiedades de fractura que presentan. También se plantean diferentes modificaciones del método que permiten potenciar sus posibilidades. Se observa que al mejorar la perfección cristalina de los materiales estudiados, el término esencial aumenta en detrimento del término no esencial. También se demuestra que la presencia de etileno en los EPBC minimiza la gran dependencia que presentan las propiedades de fractura del PP homopolímero al variar la temperatura, y se relaciona este comportamiento con los cambios de los mecanismos de deformación predominantes en el material.
In this work, the study of the fracture properties of polypropylene (PP) and ethylene-propylene block copolymers (EPBC) films by means of the Essential Work of Fracture (EWF) method is presented. This method is considered as a suitable alternative for applying Fracture Mechanics to ductile films, allowing the separation of the total fracture energy into two different items: an essential term, related to the actual fracture work, and a non essential term, related to the plastic deformation energy dissipation occurring in the region surrounding the fracture path.
In a first part, the optimal EWF method test conditions for ductile plastic films are studied, by analysing the influence of such test variables as the specimen dimensions, the test rate or the fracture mode.
In a second part, the relationship between the fracture parameters obtained by applying the EWF method and different materials structural properties are studied. Among these properties, the influence of the crystalline characteristics, modified by an annealing process before the tests, and that of the ethylene content at different test temperatures have been analysed.
Various mechanical, fracture and physico-chemical characterisation techniques have been applied.
The results show that the EWF method is very suitable to assess the fracture of polymeric films, and therefore to study the relationship between their structure and the fracture properties that they present. In addition, various modifications of the method are proposed in order to improve its possibilities.
It is observed that as the crystalline perfection grows, the essential term increases but the non-essential term decreases. It is also shown that the ethylene presence in the EPBC minimises the strong temperature dependence shown by the fracture properties of the PP homopolymer. This behaviour is related to the predominant deformation mechanisms in the material.
Cet ouvrage présente l'étude des propriétés de rupture de films de polypropylène (PP) et de copolymères éthylène-propylène en blocs (EPBC) par moyen de la methode du Travail Essentiel de Rupture (EWF). Cette technique se révèle comme une alternative très adaptée à l'application de la Mécanique de la Rupture aux films ductiles, et permet la séparation de l'énergie totale de rupture en un terme essentiel, qui fait référence au travail réel de rupture, et en un terme non essentiel, relatif à la dissipation d'énergie de déformation plastique autour du chemin de rupture.
Dans une première partie, les conditions optimales d'essai de la technique EWF pour l'application aux polymères ductiles sont étudiées, tout en analysant l'influence de variables d'essai telles que les dimensions de l'éprouvette, la vitesse de l'essai, ou le mode de rupture.
La deuxième partie est consacrée à l'étude de la relation entre les paramètres de rupture obtenus par la méthode EWF et différentes propriétés de la structure du matériau. Parmis celles-ci, nous avons analysé l'influence des caractéristiques cristallines, modifiées par un processus de recuit préalable aux essais, et de l'effet du contenu en éthylène à différentes températures d'essai. Plusieurs techniques de caractérisation, aussi bien mécaniques, que de rupture, que physico-chimiques ont été utilisées.
Les résultats montrent que la méthode EWF est très adaptée à la caractérisation de la rupture de films de polymères, et permet d'étudier la relation entre leur structure et leurs propriétés de rupture. Nous présentons, aussi, différentes approches modifiées de la technique EWF qui permettent d'accroître son potentiel. Il est observé que, quand la perfection cristalline des matériaux étudiés augmente, le terme essentiel augmente lui aussi, mais le terme non essentiel présente une tendance opposée. De même, il est démontré que la présence d'ethylène dans les EPBC a un effet de minimisation de l'importante dépendence que le PP homopolymère présente vis-à-vis de la température, et ce comportement est relié aux changements des mécanismes de déformation prédominants dans le matériau.
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Höfling, Felix. "Dynamics of Rod-Like Macromolecules in Heterogeneous Materials." Diss., lmu, 2006. http://nbn-resolving.de/urn:nbn:de:bvb:19-105831.
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Höfling, Felix. "Dynamics of rod like macromolecules in heterogeneous materials." Münster Verl.-Haus Monsenstein und Vannerdat, 2006. http://deposit.d-nb.de/cgi-bin/dokserv?id=2930009&prov=M&dok_var=1&dok_ext=htm.
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Höfling, Felix. "Dynamics of Rod-Like Macromolecules in Heterogeneous Materials /." Münster, Westf : Monsenstein und Vannerdat, 2007. http://deposit.d-nb.de/cgi-bin/dokserv?id=2930009&prov=M&dok_var=1&dok_ext=htm.
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Han, Lin Ph D. Massachusetts Institute of Technology. "Nanomechanics of cartilage extracellular matrix macromolecules." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42134.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007.Includes bibliographical references (p. 187-201).
In this thesis, the shear and self-adhesion nanomechanical properties between opposing cartilage aggrecan macromolecules were probed. In addition, nanoscale dynamic oscillatory mechanical properties of cartilage and its type II collagen network was measured. Aggrecan shear nanomechanics was assessed via microcontact printing and lateral force microscopy. Lateral force between aggrecan and the probe tip, and compression of aggrecan was simultaneously measured in 0.001 - 1.0 M NaCl aqueous solutions. Using the microsized tip (Rtip ~ 2.5 [mu]m) enabled a large assembly of ~ 103 aggrecan molecules to interact simultaneously, closely mimicking the in vivo conditions.Both electrostatic and nonelectrostatic components were identified to importantly contribute to aggrecan shear. At near physiological IS (0.1 M), significant rate dependence was observed, suggestive of visco/poroelastic interactions within the aggrecan layer. By using an aggrecan end-functionalized colloidal tip, shear of two opposing aggrecan layers was assessed in a similar fashion. Lower lateral force and a more marked rate dependence were measured compared to the shear of a single layer, due to the aggrecan inter-layer molecular interpenetration and the different local z-dependent charge density distribution. The addition of Ca2+, at physiological-like 2 mM concentration, significantly affects cartilage shear by its electrostatic screening and binding effects. Marked aggrecan self-adhesion upon separation was discovered after static compression in the presence of electrostatic repulsion in physiological-like conditions.
(cont.) Aggrecan self-adhesion increases as increasing equilibration time and bath IS. Molecular origins of the adhesion, also present in vivo, include van der Waals, hydrogen bonding, Ca2+-mediated bridging, and molecular entanglements between the glycosaminogly-can branches of aggrecan. This self-adhesion could be an important factor in protecting cartilage matrix structural integrity and function via these energy-dissipative mechanisms. The nanoscale oscillatory dynamic deformation properties of both nontreated and proteoglycan(PG)-depleted (left mostly type II collagen) calf knee cartilage disks (- 0.5 mm thick) was measured by connecting an external electronic wave generator to the AFM. A significant increase in effective stiffness E and phase lag A (deformation with respect to force) as increasing frequency for both disks suggests poro/viscoelasticity are more critical at higher frequency. The PG-depleted disk shows a more marked dependence of E and A on deformation amplitude - 2 - 100 nm, as the nanostructure and nanomechanical properties of porous collagen network are more heterogeneous without the entrapment of aggrecan motif. A unique - 23 nm banding pattern along the type II collagen fibrils was observed, which may be relative to the cartilage swelling properties and the molecular interaction between aggrecan and the collagen network. Taken together, this study provides insights into molecular-level deformation of cartilage extracellular matrix (ECM) macromolecules (e.g., aggrecan, type II collagen) that are important to the understanding of cartilage biomechanical function. Ongoing studies are probing the age, disease (osteoarthritis), source and species related variations of cartilage ECM properties at the molecular level.
by Lin Han.
Ph.D.
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Eleftheriou, Lygia. "Study of macromolecule-mineral interactions on nuclear related materials." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/16816/.
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Microbes have been identified close to contaminated sites such as nuclear-waste repositories indicating their ability to interact with radionuclides. One of the main mechanisms bacteria use involves the reduction of highly mobile radionuclides to less mobile minerals, often in the form of oxides. The precipitated minerals are found located at the cell wall or close to the external components of the bacterial cell suggesting a possible interaction of cell wall components or external components of the tested bacteria with the precipitated particles. Tests on ceria, urania, thoria and europium oxide confirmed that several biomolecules are responsible for the observed localisation. The first experiments used lipopolysaccharides (LPS), found at the outer site of Gram negative bacterial cells and resulted in successful sorption of LPS on all four minerals. The Purpald assay was used to quantify LPS before and after the interaction and confirmed the attachment of the biopolymers to the oxides with ΔG values in the range of physisorption (-3 to -25 kJ/mol) for all systems. ATR-FTIR, zeta potential analysis and electron microscopy also confirmed the attachment of the biomolecules on the minerals. Mycolic acids and peptidoglycans, components of Gram positive bacteria, were also assessed for their ability to interact with ceria and europium oxide. Mycolic acids showed successful sorption profiles with ΔG values in the physisorption range (-10 to -17 kJ/mol) for all systems, highly dependent on the experimental conditions. In addition, Molecular Dynamics simulations were used to examine the interaction of mycolic acid with ceria under natural conditions (pH7) in the presence of Na+ and the calculated binding energy (-11.598 kJ/mol) agreed well with the experimental results for the corresponding system (-16.485 kJ/mol). Additionally, preliminary tests on peptidoglycan interactions resulted in successful sorption of the biomolecule on both ceria and europium oxide with ΔG values in the physisorption range (-8 to -10 kJ/mol). ATR-FTIR and zeta potential analysis confirmed the attachment of mycolic acid and peptidoglycan on the minerals tested. These results suggest that the observed localisation of mineral within the bacterial cell walls are related to lipopolysaccharide and peptidoglycan-mediated sorption and have potential uses in treatment of nuclear waste and biomining processes.
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Höfling, Felix [Verfasser]. "Dynamics of rod-like macromolecules in heterogeneous materials / Felix Höfling." Münster : Verl.-Haus Monsenstein und Vannerdat, 2006. http://d-nb.info/997139641/34.
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Gottlieb, Ronny, and Karl-Friedrich Arndt. "Intelligente Werkstoffe - Vom Makromolekül zum intelligenten Material." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1188378259921-41093.
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Sensitive polymers change their conformation in response to even a little change in the environmental conditions, e. g. temperature, pH value, concentration of a second component, or light. Crosslinking of these polymers and their swelling in water forms smart hydrogels (intelligent hydrogels). Different shapes and dimensions are possible: bulk gel, thin layers, intraor intermolecular crosslinked globular particles. Smart hydrogels display two important properties: Their volume (swelling degree) depends on the environment and can be switched between two states. The gels can thus be used as actuators. As the change in the gel properties is stimulated by changes in the environment, the gels can also be used as sensors. Smart hydrogels are suitable for applications in microsystems, and gel particles are potential carriers for drugs in the human bodyUmgebungssensitive Polymere ändern in Abhängigkeit von Umgebungsbedingungen, wie zum Beispiel dem Licht, der Temperatur, dem pH-Wert oder der Konzentration einer zweiten Komponente neben dem Polymer, drastisch ihre Molekülgestalt. Vernetzt und in Wasser gequollen, bilden sie sogenannte smarte Hydrogele. Dabei werden die Besonderheiten eines Makromoleküls, dessen Eigenschaften durch die Umgebung beeinflusst werden, auf ein polymeres Material übertragen. Dies kann ein großer Körper, eine dünne Schicht oder ein Nanopartikel sein. Das Volumen der smarten Hydrogele kann zwischen zwei Zuständen geschaltet werden. Dabei können die Hydrogele wie Aktoren eine Kraft ausüben. Da das Schalten durch die Umgebung stimuliert wird, sind sie als Sensoren verwendbar. Die Polymerstrukturen sind miniaturisierbar, sodass smarte Hydrogele als Komponenten in Mikrosystemen angewendet werden können. Zum Beispiel werden die Partikel zur kontrollierten Abgabe von Arzneimittelwirkstoffen verwendet
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Del, Regno Annalaura. "Microscopic behaviour of porous macromolecules." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/microscopic-behaviour-of-porous-macromolecules(d1eb5218-a2f3-41db-a6ee-7e7d45e37f4d).html.
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This Thesis investigates computationally the behaviour of two novel microporous materials,organic molecules of intrinsic microporosity (OMIMs) and polymers of intrinsic microporosity(PIMs). OMIMs and PIMs are organic amorphous materials, which achieve microporosityby packing inefficiently. The design of amorphous materials is challenging because their self-assembly process is not known. Predictive molecular simulations can help in recognising thefeatures that affect the properties of these materials, and guiding in the design of new structures with desired performances. OMIMs are highly concave shaped molecules, consisting of a core and a series of termini, which provide the geometry and the general chemical environment of these structures, respectively. PIMs are polymers consisting of fundamental units such as stiff segments and contortionsites, which form either linear or network like porous structures. While chronologically olderthan OMIMs, they share with them a common design philosophy. This Thesis is presented in alternative format, and the results, consisting of five journal articles,can be divided into three main parts. The first part focuses on recognising a reliable method to generate representative models ofOMIMs. Different computational protocols and molecular mechanics descriptions were investigated; the development of the utilised simulation protocol was based on comparison of several simulation methods and force fields to experimental wide angle X-ray scattering (WAXS) patterns. Our work suggests that OMIMs can be described successfully by both PCFF and UFF; the final packed material can be generated using a 21-step compression-decompression molecular dynamics protocol, previously developed to generate virtual model of PIMs. The examination of the simulated structures has provided a deeper understanding of the features that affect the packing behaviour of this class of materials, suggesting that OMIMs have a greater microporosity when the molecules are the most shape-persistent, which required rigid structures and bulky end groups. The adsorption behaviour described by different generic force fields (Dreiding, OPLS and UFF) was also investigated to guide on the selection of the solid-fluid interactions when modelling OMIMs, for future comparison with experimental data. Our results suggest that very strong interactions between argon adsorbate and OMIM-based framework are described by UFF, while the weakest adsorbent is obtained using OPLS force field. The second part of the research focuses on assessing the effect that different termini’s chemistry and bulkiness have over the packing behaviour, adsorption properties and solubility of the OMIMs. The microporous frameworks generated by two selected families of cruciform OMIMs (benzene and naphthalene- based) were investigated with respect to their packing behaviour, porosity and adsorption properties. Our analysis suggests that the final density of the material, as well as the surface area and pore volume, depend on the ending group’s bulkiness. Bulkier molecules lead to materials with lower densities, but it was found that the adsorption behaviour is not just related to the material’s density, but also to the pore size and shape, which are determined by the way the molecules pack. The relationship between adsorption capacity and physical properties was analysed and the role of surface area, free volume and enthalpic interaction was used to identify different adsorption regimes. It was found that the uptake of argon at low pressure is proportional to the strength of the adsorbent-adsorbate interaction while at moderate pressure it is dependent on the free volume and surface area. The dissolution of three cruciform OMIMs was investigated in dichloromethane, ethyl acetateand toluene. Direct interface molecular dynamics simulations showed that the solubility process consists of two steps; the diffusion of the solvent in the OMIM-rich phase, and the departure of the OMIMs in the solvent bulk. We proposed a simple model to represent this mechanism. Furthermore, results from infinite dilution simulations show that the solvent-OMIMs interactions can be related to the chemistry of the OMIMs and to the solvent’s properties. We found that, in general, increasing the length of the OMIM’s arm affects negatively the solubility of the material, while adding bulky alkyl groups favours the interaction with the solvent molecules. The third part concentrates on the characterisation of PIMs and their application as CO2 adsorbent. Properties of four polymers of intrinsic microporosity containing Tröger’s base units were assessed for CO2 capture experimentally and computationally. Structural properties included average pore size, pore size distribution, surface area, and accessible pore volume, whereas thermodynamic properties focused on density, CO2 sorption isotherms, and enthalpies of adsorption. It was found that the shape of the contortion site plays a more important role than the polymer density when assessing the capacity of the material, and that the presence of a Tröger base unit only slightly affects the amount adsorbed at low pressures, but it does not have any significant influence on the enthalpy of adsorption fingerprint. A comparison of the materials studied with those reported in the literature allowed us to propose a set of guidelines for the design of polymers for CO2 capture applications.
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Almqvist, Nils. "Studies of plasma-facing materials and macromolecules using scanning probe microscopy." Doctoral thesis, Luleå tekniska universitet, Materialvetenskap, 1995. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16824.
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The main topic of this thesis is experimental analysis of material surfaces using scanning probe microscopies. These microscopes are used for characterization through high-resolution topographical imaging, but also for controlled modification of surfaces and molecules. The surface characterization includes evaluation and development of fractal methods for surface roughness determination. The term modification is used for manipulating the structures on a microscale by scraping them with a tiny tip. The major application of this technique in the present work is the analysis of effects induced by plasma-surface interactions. Such studies are fundamental in the understanding of erosion and deposition processes on the first wall in controlled fusion devices. In this work, scanning probe microscopes were for the first time used for studying such plasma-facing materials. Both the surface structure and composition have to be known in order to evaluate new wall-materials for fusion reactors. The materials studied here are graphites, SiC/Al coatings, graphite-silicon mixtures and various silicon carbide based composites. They were all exposed to plasmas, either to lowenergy deuterium plasmas and ions in laboratory experiments, or to the plasma in a socalled tokamak. The results show the usefulness of these high-resolution microscopes in the study of plasma-surface interaction. Several other surface sensitive techniques were also applied, at the home laboratories of our collaborators, the most important ones being Rutherford backscattering spectroscopy and nuclear reaction analysis. The scanning probe microscopy in combination with the ion-beam analysis made it possible to trace fine structural features on the surfaces and to measure the surface roughness. The main results are: (i) the detection of the initial stages of bubble/blister formation on CSi mixtures, SiC/AI coatings and graphites; (ii) the morphological changes and the physical properties of the silicon carbide composites; (iii) the distinction of radiation damages on different phases of multicomponent composites; (iv) the estimation of layer thickness with scanning probe microscopy; (v) the determination of the structure of codeposited layers formed during exposure in a tokamak; (vi) the uptake of deuterium by the materials. The atomic force microscope has also been used to study the human protein spectrin, and we managed to image free spectrins with molecular resolution in an almost natural environment. The elongated spectrin macromolecule was found to be 100 rim long and 5 nm broad. Indications of a substructure were observed. The force between the sensor tip and the molecules was crucial, both for sample movement, manipulation and image resolution. Therefore, the instrument was rebuilt to operate with so called tapping-mode in liquid. Preliminary results with this method on spectrin are presented.Godkänd; 1995; 20070410 (ysko)
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Van, Schalkwyk Welmarie. "Self-assembly of amphiphilic discotic materials." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/79799.
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Thesis (MSc)--Stellenbosch University, 2013.ENGLISH ABSTRACT: The creation of nanometer-scale (nanoscale) materials has fascinated and inspired the scientific community for more than a quarter of a century because of the wide range of applications of these materials, e.g. applications in drug delivery, medicine, tissue engineering, memory storage, display and audio devices, semiconductors, etc. π-Conjugated dendrimers have a proposed flat packing arrangement. An alternating phenyl isoxazole dendrimer system was developed to investigate this phenomenon. The synthesis of this dendritic system was attempted by divergent and convergent approaches. Preparation of the second generation failed because some functional groups inhibited the monomers to react to the first generation. Other examples of nano materials that have attracted a vast amount of interest are the so-called discotic amphiphiles. Discotic amphiphilic molecules have the potential to self-assemble into helical architectures. Discotic systems bearing chiral polar side chains (one and three respectively) were developed. Their self-assembly was investigated in variable concentration and variable solvent composition experiments. These systems did show signs of aggregation in UV-vis and CD spectroscopy experiments. Thread-like helical structures were observed with transmission electron microscopy.
AFRIKAANSE OPSOMMING: Nanometer-skaal materiale inspireer en fassineer wetenskaplikes al vir meer as 25 jaar as gevolg van hulle wye verskeidenheid toepassings bv.: die vervoer van geneesmiddels, weefsel ontwerp, geheue stoorspasie, digitale skerms, klank toerusting, geleiers, ens. π-Gekonjugeerde dendrimere het 'n plat drie dimmensionele rangskikking. 'n Afwisselende feniel isoxazole dendrimer stelsel was ontwikkel om hierdie verskynsel te ondersoek. Die sintese van hierdie dendritiese stelsel is aangepak deur divergerende en konvergerende benaderings. Sintese van die tweede generasie het misluk omdat sommige funksionele groepe die monomere geïnhibeer het om te reageer met die eerste generasie. Ander interessante voorbeelde van nano materiale, is die sogenaamde skyfvormige amphiphiles. Skyfvormige amphiphiles het die potensiaal om spontaan te versamel in heliese strukture. Skyfvormige molekules met chirale polêre sykettings (een en drie onderskeidelik) is ontwikkel. Hulle potensiaal om spontaan te versamel is ondersoek met wisselende konsentrasie en wisselende oplosmiddel samestelling eksperimente. Hierdie stelsels het tekens van versameling gewys in UV-vis en CD-spektroskopiese eksperimente. Staaf-vormige heliese strukture is waargeneem met transmissie-elektronmikroskopie.
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Ehrlich, Deborah J. C. "Synthetic strategies for control of structure from individual macromolecules to nanoscale materials to networks." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122451.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 2019Cataloged from PDF version of thesis.
Includes bibliographical references.
Chapter 1. Aqueous self-assembly of prodrug macromonomers. A series of highly tunable micelles for drug delivery were made from norbornene based poly(ethylene glycol) macromonomers with covalently linked drugs. A total of five macromonomers were made using three different drugs (telmisartan, paclitaxel, and SN-38) and three different drug loadings. Combinations of these macromonomers were then allowed to self assemble into micellar aggregates. The size, stability, and shape of these micellar aggregates were controlled with the highly versatile structure. Chapter 2. Post micellization modification of norbornene-containing prodrug macromonomers. Highly tunable micelles for drug delivery were functionalized after their selfassembly. Post-micellization inverse electron demand Diels-Alder reactions of norbornenes and tetrazines were used to signal changes in micelle size and stability through the addition of either hydrophilic or hydrophobic tetrazines.
Thiol-ene additions reactions were used to increase micelle size and form chemically crosslinked nanoparticles. These modifications of norbornene-containing prodrug macromonomer assemblies illustrate their versatility. Chapter 3. Synthesis of polymers by iterative exponential growth. A scalable synthetic route that enables absolute control over polymer sequence and structure has remained a key challenge in polymer chemistry. Here, we report an iterative exponential growth plus side-chain functionalization (IEG+) strategy for the production of macromolecules with defined sequence, length, and stereoconfiguration. Each IEG+ cycle begins with the azide opening of an enantiopure epoxide, followed by side chain functionalization, alkyne deprotection, and copper-catalyzed azide-alkyne cycloaddition (CuAAC). These cycles have been conducted to form unimolecular macromolecules with molar masses of over 6,000 g/mol.
Subsequent modifications to IEG+ allow for the functionalization of monomers prior to the IEG+ cycle, expanding the library of compatible side chain chemistries. Chapter 4. Introduction to elastomer toughening strategies. Silicone elastomers are ubiquitous. Here, silicone elastomers are discussed in terms of network structure, the impact of network structure upon physical properties, and modifications of network structure in order to achieve desired physical properties. Fillers, the standard toughening strategy, are discussed in conjunction with entanglement density. Focus is placed on the impact of entanglement density on material properties. Topological networks are discussed and noted for their stress dissipative properties. Chapter 5. Topology modification of polydimethylsiloxane elastomers through loop formation. Topological networks are well known for their stress dissipation through the pulley effect leading to soft, extensible materials.
Combining these properties with a traditionally crosslinked network to produce a hybrid material allows for enhanced extensibility without a loss in modulus. Here, such hybrid networks were made with poly(dimethyl siloxane) polymers of a range of molecular weights. Side-loop polymer brushes were synthesized and then crosslinked to create hybrid networks with the statistical formation of topological bonds. These materials were characterized through tensile testing. Elastomers formed with the same molecular weight polymer in both side-loops and network formation did not show mechanical properties that depended upon the fraction of networks used for brush formation. Elastomers made with long polymers in brush formation and shorter polymers for network formation resulted in highly extensible systems without significant loss in modulus.
by Deborah J.C. Ehrlich.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Chemistry
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Durmus, Asuman. "Realization Of Neutral State Green Polymeric Materials." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610738/index.pdf.
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Polymeric electrochromic materials that has as one of the three complementary colors (red, green, and blue) in the neutral form and become transparent via oxidation (or reduction), has a crucial importance towards use of these materials in electrochromic devices and displays. To reflect red or blue color in neutral state, the materials have to absorb at only one dominant wavelength. On the contrary, to have a green color, there should exist at least two simultaneous absorption bands in the red and blue regions of the visible spectrum where these bands should be controlled with the same applied potential. The transmissivity in the oxidized state is significantly important in addition to the neutral state color of the polymer. The optical contrast between the states is the decisive point for use of these materials for many electrochromic applications, especially as smart windows and displays. Hence, the material should possess two absorption bands with definite maximum points, and upon oxidation these bands should simultaneously vanish to have a transmissive state. A donor&ndashacceptor approach can be utilized to solve this puzzle. It has been shown that insertion of alternating donor&ndash
acceptor units on the polymer backbone leads to a significant decrease in band gap due to the increased double bond character in the structure. In this study novel donor-acceptor type polymers were synthesized, and electrochromic properties were investigated in detail. PBDT is the first green electrochromic material which has a highly transmissive sky blue oxidized state. PDETQ was shown to be one of the few examples of neutral state green polymeric materials in literature. PDEQ has a bluish green color in the neutral state and a highly transmissive light blue oxidized state.
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Park, Juhyun Ph D. Massachusetts Institute of Technology. "Adsorption and multilayer assembly of charged macromolecules on neutral hydrophobic surfaces and applications to surface patterning." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36210.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006.Includes bibliographical references.
Micrometer- and nanometer-scale chemical patterns are indispensable and ubiquitous in a range of applications, such as optoelectronic devices and (bio) chemical sensors. This thesis studies chemical surface patterning utilizing polyelectrolyte multilayers for electronic and biological applications. It focuses on both fundamental study and application development in the field of layer-by-layer self-assembled composite thin films, with the goal of defining new concepts allowing for technological breakthrough. In the process of completing it, a multicomponent patterning technology that has been a bottleneck in realizing practical devices utilizing the multilayers has been developed. To achieve this goal, a multilayer transfer printing concept was applied to serial printing of individual device components. The main achievements include fundamental studies about uniform multilayer assembly of charged macromolecules on neutral hydrophobic surfaces as the principle of the technique, and the demonstration of multicomponent patterning of polyelectrolyte/nanoparticle composite thin films on a flexible substrate.
(cont.) Extending the technique toward nanometer-scale patterning, a new polymeric mold material that was suitable for sub-100 nm structuring was studied and used for chemical patterning for flow control in microfuidic devices and nanoparticle assembly for potential biological applications, combined with polyelectrolyte multilayers.
by Juhyun Park.
Ph.D.
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Kumar, Abhishek. "Development, characterization and experimental validation of metallophthalocyanines based microsensors devoted to monocyclic aromatic hydrocarbon monitoring in air." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22635/document.
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Résumé indisponibleThis PhD work is dedicated to investigate potentialities of phthalocyanines materials to realize a Quartz Crystal Microbalance (QCM) sensor for Benzene, Toluene and Xylenes (BTX) detection in air. The goal is to develop a sensor-microsystem capable of measuring BTX concentrations quantitatively below the environmental guidelines with sufficient accuracy. To achieve these objectives, our strategies mainly focused on experimental works encompassing sensors realization, sensing material characterizations, development of gas-testing facility and sensor testing for different target gases. One of the main aims is to identify most appropriate phthalocyanine material for sensor development. After comparative sensing studies, tert-butyl-copper phthalocyanine based QCM device is found as most sensitive and detail metrological characteristics are further investigated. Results show repeatable, reversible and high magnitude of response, low response and recovery times, sub-ppm range detection limit, high resolutions and combined selectivity of BTX gases among common atmospheric pollutants. Special focus is given to understand the gas/material interactions which are achieved by (a) XRD and SEM characterizations of sensing layers, (b) formalization of a two-step adsorption model and (c) assessing extent of diffusion of target gas in sensing layer. At last, possible ageing of sensor and suitable storage conditions to prevent such effect are investigated
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PATWARDHAN, SIDDHARTH VIJAY. "SILICIFICATION AND BIOSILICIFICATION: THE ROLE OF MACROMOLECULES IN BIOINSPIRED SILICA SYNTHESIS." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1054325597.
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Small, Aaron Charles. "Novel hybrid materials and their applications : a thesis submitted to the Victoria University of Wellington in fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry /." RestrictedArchive@Victoria -- VUW staff and students only, 2008. http://restrictedarchive.vuw.ac.nz.helicon.vuw.ac.nz/handle/123456789/1298.
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Yu, Tingting. "Solid state luminescent molecules, macromolecules and materials, their response to stimuli and their applications in devices." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEN061.
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Au cours de cette thèse, nous avons développé de nouveaux chromophores conjugués luminescents présentant une alternance de groupements donneurs et accepteurs, avec une attention particulière quant à leurs propriétés d’émission dans le rouge et proche infra-rouge à l’état solide ou agrégats. Nous avons étudié l’influence de la longueur de chaine et de la nature de la substitution donneur/accepteur non seulement sur les propriétés optiques en solution mais aussi (et surtout) sur le matériau agrégé. Enfin, en utilisant les propriétés spécifiques de certains des composés développés selon cette approche, nous avons exploré leur potentiel pour des applications allant de matériaux fluorochrome stimuli-responsifs (sous forme de films) à l’élaboration de sondes à deux photons émettant dans le proche infra rouge pour l’imagerie biologique. Les principaux accomplissements de cette thèse sont les suivant: 1/ de nouveaux polymères alternant des motifs triarylamine (ou carbazole)/ tetraphenylethylene (TPE) dans leur chaine principale ont été synthétisés. Leurs propriétés d’émission à l’état solide présentent des caractéristiques d’agrégats-J, peu courant dans les dérivés TPE, ce que nous attribuons à l’arrangement linéaire des chaînes polymères; 2/ Une nouvelle famille de colorants diphenylamine/benzobisthiazole et leurs dérivés oligomères ont été synthétisés. Leurs propriétés de luminescence présentent une sensibilité marquée à la protonation, que nous avons utilisée dans la conceptions de dispositifs luminescents commutables par stimuli acide/base; 3/Nous avons exploré la possibilité d’introduire des modifications chimiques complémentaires sur cette nouvelle famille de chromophores, afin d’obtenir des composés luminescents à l’état solide dans le proche infrarouge, en particulier par un changement de la nature de la transition électronique à transfert de charge intramoléculaire vers une transition cyanine, par le biais d’une quaternarisation des fonction benzobisthiazole. D’autres modifications ont conduit à une amélioration de la biocompatibilté des molécules, de leurs propriétés AIE, ou encore de leur spécificité de marquage cellulaire; 4/ Ces nouveaux composés présentent une luminescence photo-commutable (de type allumé/éteint), qui pourrait présenter un intérêt dans l’élaboration d’agents de contraste pour l’imagerie de microscopie super-résolueIn this thesis, we developed new luminescent conjugated chromophores presenting an alternation of electron donor and acceptor groups, with a specific focus on their emission properties in aggregates or solid states in far-red or near infrared region. We studied the influence of chain length and donor/acceptor substitution not only on the optical properties of the isolated compounds, but also (and especially) on the material in its aggregated state. Finally, taking advantages of these specific properties of some of the as-designed candidates, we explored their potential applications ranging from fluorochromic stimuli-responsive sensors (in film form) to red and NIR luminescent two-photon probes for biological imaging. The main achievements of this thesis are the following: 1) new alternating triarylamine or carbazole / tetraphenylethylene (TPE) polymers were synthesized. Their solid state luminescence poseeses typical J-aggregates emission features in solid state, unusual in TPE derivatives that we relate to the linear polymeric nature of the object; 2) A new family of diphenylamine / benzobisthiazole chromophores and derived oligomers were synthesized . Their luminescence properties present a marked sensitivity to protonation, which we took advantage of in the making of acid-base responsive luminescent devices; 3) we explored the possibility of additional chemical transformations of the newly designed chromophore, in order to achieve solid state NIR emission, in particular by means of a change in the character of the electronic transition from Intra-Molecular Charge Tranfer (ICT) to Cyanine transition owing to benzothiazole quaternarization. Other modifications resulted in improvement of their AIE properties, bioavailability and selectivity of their cellular compartments staining ability; 4) These new compounds present a reversible photoinduced “on-off” switching of their luminescence properties, which might present an interest in the design of contrast-agents for super resolution imaging
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San, Juan Ocete Alexis. "Nuevos materiales macromoleculares formados por la unión de moléculas con estado birradical triplete asequible térmicamente." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/587192.
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Estudios previos de nuestro grupo de investigación describieron moléculas orgánicas heterocíclicas, aparentemente de capas cerradas que presentan carácter birradical triplete asequible térmicamente.
La formación de esta especie birradicalaria proviene de la rotura de un doble enlace exocíclico por rotación de dicho enlace. Un factor de estabilización del biradical formado es la conjugación de uno de los electrones desapareados con un ciclo aromático aceptor de electrones y el otro con otro ciclo dador de electrones, con la consiguiente deslocalización de los mismos, de manera independiente, en cada una de dichas partes. Además, tanto los datos experimentales como los teóricos han mostrado que, si las moléculas estudiadas contienen protones ácidos, la formación de los correspondientes aniones hacen aumentar de manera considerable la población de moléculas en estado birradical triplete.
Se exploró un elevado número de estructuras buscando cuales eran las características mínimas que debían presentar para tener el citado estado birradical triplete asequible térmicamente y, por lo tanto, un posible carácter paramagnético. Este trabajo dio como resultado una gran familia de nuevas moléculas (más de 50 compuestos) que presentaban la propiedad estudiada y de las que se pudo deducir un modelo molecular general para todas ellas.
A partir del modelo anterior se buscó en la literatura moléculas que pudieran presentar las anteriores características electrónicas y se encontraron el Dasatinib y sus análogos, fármaco de segunda generación que se utiliza en el tratamiento de algunos tipos de cáncer y el p-HBDI, cromóforo de la proteína verde fluorescente (‘Green Fluorescent Protein’, GFP). Este último compuesto, de fácil síntesis y estudiado desde muchos puntos de vista pero no desde el nuestro, se tomó como modelo para la mayor parte de nuestros trabajos.
Ante los precedentes anteriores, la presente Tesis Doctoral ha consistido en obtener materiales macromoleculares formados por dichas moléculas, con el objetivo de analizar la propiedad que nos interesa cuando éstas moléculas se hallan en entornos poliméricos. Para ello, se han desarrollado diversos métodos de síntesis.
Previamente, ha sido necesario sintetizar derivados de las unidades de menor tamaño que presentan un mayor carácter birradical triplete asequible térmicamente
funcionalizadas adecuadamente para ser unidas sobre los diferentes soportes poliméricos. Se han introducido diversos tipos de funcionalización para intentar anclar dichas moléculas, empleando diversas opciones de síntesis, siendo la funcionalización principal introducida una cadena de 2-hidroxietilo, un grupo funcional versátil que permite llevar a cabo bastantes transformaciones sintéticas. Además, se han preparado y estudiado modelos auxiliares simples, análogos de los sistemas macromoleculares objetivo de nuestro trabajo, con el objeto de estudiar previamente las reacciones que posteriormente se ensayarían a nivel macromolecular.
Una vez obtenidas las moléculas con carácter birradical triplete asequible térmicamente funcionalizadas adecuadamente, se unieron a diferentes soportes poliméricos. El primero fue el ácido poliacrílico (PAA), mediante esterificación entre los grupos ácidos de la cadena polimérica y los grupos hidroxilo de las moléculas anteriores. Además, se intentaron llevar a cabo sin éxito polimerizaciones radicalarias para generar el mismo tipo de material macromolecular. Dada la dificultad de purificación de estos compuestos se decidió utilizar soportes poliméricos con grupos funcionales NH2. Estos soportes fueron la polietileimina ramificada (PEI) y el (aminometil)poliestireno reticulado. Asimismo, se estudió la posibilidad de emplear estructuras dendriméricas como alternativa a los sistemas anteriores, por su estructura química bien definida.
Intentar unir todas las moléculas que han presentado carácter birradical triplete asequible térmicamente sobre soportes poliméricos sería un trabajo sumamente extenso, con lo que, básicamente, nos hemos centrado en la obtención de análogos poliméricos del p-HBDI y derivados.
La técnica de elección para el estudio de estos productos poliméricos de los que se esperaban que fueran paramagnéticos ha sido la Resonancia Paramagnética Electrónica (RPE, ‘Electron Paramagnetic Resonance’, EPR).
Los resultados obtenidos han confirmado los estudios previos que nos permiten predecir qué moléculas presentan la propiedad indicada en el título de esta Memoria.Studies carried out previously by our research group show that there are heterocyclic organic molecules, seemingly closed layers and without any metal atom, presenting thermally affordable triplet biradical character. The formation of these biradical species comes from an imine double bond break by simple conformational changes of this bond. A stabilization factor of the biradical formed is to be included in an electron acceptor part (e.g. acridine) and another electron donor part (e.g. benzothiazole), with the consequent relocation of the unpaired electrons independently in each of such parts. In addition, if the studied molecules contain acidic protons, the formation of the corresponding conjugated base make increase significantly the population of molecules in a triplet biradical state, due to the negative charge generated, that stabilizes better the unpaired electrons. More than 50 compounds have been synthesized and have shown the studied feature, being able to get a general molecular model for all of them. Bibliographic search have also shown that there are natural products which include this model in its structure, and for this reason, paramagnetic response (EPR). These biomolecules are Dasatinib and its analogues, and p-HBDI, chromophore of green fluorescent protein (GFP), being the last one included in this Thesis in order to give validity to the model made up of molecules previously studied. Firstly, our molecules have been functionalized properly to be united on the different polymeric supports. Then, the work has consisted of getting macromolecular materials formed by these molecules to see how affects the property when these molecules are in a polymeric environment. To do this simpler, analog auxiliary models of macromolecular systems have been synthesized and have been used as a guide, for its both synthesis and characterization. Polymers with different structures have been used by the possible influence on the formation of biradical species. The union of these molecules have been carried out on polyacrylic acid (PAA), polyethyleneimine branched (PEI), the (aminomethyl) cross-linked polystyrene as well as dendrimeric structures, focusing, exclusively, in obtaining polymeric analogues of the p- HBDI and its derivatives. For the study of these products have been carried out using the Electron Paramagnetic Resonance (EPR), comparing the macromolecular systems obtained with their low molecular weight precursors. Furthermore, other systems with possible poliradical states as dimers and tetramers have been proposed.
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Noell, John Lee Watson. "The preparation and characterization of PEK/TEOS glasses by the sol-gel method." Thesis, Virginia Tech, 1987. http://hdl.handle.net/10919/44056.
Full textAbstract:
Over the last twenty years, substantial emphasis has been placed on the development
of a new class of inorganic glasses using the sol-gel approach. This technique utilizes metal
alkoxide precursors such as tetraethylorthosilcate (TEOS) to build an inorganic glass matrix
out of solution by a two step poly(hydrolysis-condensation) reaction mechanism. The benefits
of making ceramics by this method include considerable energy savings due to the lower
sintering temperatures required to form the densified glass and the ability to produce multi-component
amorphous materials that can not be made through the traditional firing processes.
As a result of this last possibility, polymer researchers have sought to develop spin-off
hybrid inorganic-organic network systems that can be prepared by the sol-gel method using
reactively functionalized oligomers and/or monomers along with the metal alkoxide precursors.
These types of organically modified multi-component glasses could have enormous potential
from an applications standpoint because the systemâ s mechanical and physical
features can be tailored in accordance to the organic and polymeric materials chosen.
One such inorganic-organic system prepared by this procedure is the new PEK/TEOS
glasses. The PEK represents the bisphenol-A polyarylene ether either ketone thermoplastic
polymer endcapped with triethoxysilane functional groups. By mixing the PEK and
TEOS components at different weight compositions in the starting sol-gel reaction solution,
change in the mechanical properties is observed as the TEOS content is increased for the final,
thin film glasses. Also, a poor extent of reaction or degree of incorporation of the PEK
oligomer is revealed which has been attributed to the vitrification of the glass before the PEK
endgroups have a chance to react. To alleviate this problem, thermal treatments are employed
to further the sol-gel reaction and to complete the network formation in the PEK/TEOS
glasses. After the thermal treatments, the change in the mechanical and physical properties are monitored, and the data retlects systematic trends in regards to the TEOS content and the
temperature of the thermal treatment utilized. In addition to these results, some speculative
information is provided on the temperature sensitivity and the rate of curing of the PEK/TEOS
glasses during the thermal treatments.Master of Science
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Atak, Samed. "Soluble Alkyl Substituted Poly(3,4propylenedioxyselenophne)s: A Novel Platform For Optoelectronic Materials." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613106/index.pdf.
Full textAbstract:
In this study, optical and electrochemical properties of regioregular and soluble
alkyl substituted propylenedioxyselenophene based electrochromic polymers, namely
poly(3,3-dibutyl-3,4-dihydro-2H-selenopheno[3,4-b][1,4]dioxephine) (PProDOS-C4),
poly(3,3-dihexyl-3,4-dihydro-2H-selenopheno[3,4-b][1,4]dioxephine) (PProDOS-C6), and
poly(3,3-didecyl-3,4-dihydro-2H-selenopheno[3,4-b][1,4]dioxephine) (PProDOS-C10),
which were synthesized via electrochemical polymerization, were investigated. It is
noted that these unique polymers have low band gaps (1.54 &ndash1.64 eV) and they are exceptionally stable under ambient atmospheric conditions. For example, polymer films retained 84-96 % of their electroactivity after five thousands cycles. The percent transmittance of PProDOS-Cn (n= 4, 6, 10) films found to be between 55-59 %. Furthermore, these novel soluble PProDOS-Cn polymers showed electrochromic behavior: a color change form pure blue (L = 57.31, a = -13.18, b = - 42.68) to highly transparent state (L = 91.74, a = 2.52, b = -1.30) state in a low switching time (1.0 s) during oxidation with high coloration efficiencies (328 &ndash
864 cm2/C) when compared to their close analogues.
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Wu, Huangli. "Computational simulation of dynamics of nematic liquid crystals in the presence of nanoparticles and biological macromolecules." Master's thesis, Mississippi State : Mississippi State University, 2006. http://sun.library.msstate.edu/ETD-db/ETD-browse/browse.
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Eroglu, Gulden. "Isocyanate Functionalization Of Nano-boehmite For The Synthesis Of Polyurethane Organic-inorganic Hybrid Materials." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12612930/index.pdf.
Full textAbstract:
In this study, organic-inorganic hybrid materials were prepared from polyurethane and boehmite. It was achieved by polymerizing monomers in the presence of functional nano-particles of boehmite with cyanate groups. The produced polyurethane organic-inorganic hybrid materials with enhanced mechanical properties were used for coating applications. Plate-like boehmite nano-particles were produced by hydrothermal process from aluminum hydroxide which was first ground in a high energy ball-mill, and then, processed hydrothermally under pressure and high temperature in a reactor. The surface morphology and crystal structure of boehmite were investigated by Scanning Electron Microscopy and X-Ray Diffraction analyses, respectively. The molecular structures of boehmite particles were investigated by Fourier Transform infrared spectroscopy. Furthermore, Brunauer-Emmett-Teller analysis and Photon Correlation Spectroscopy analysis were carried out to determine the surface area and the size of particles. Then, plate-like boehmite nano-particles were functionalized by the reaction of their hydroxyl groups with 1,6-hexamethylene diisocyanate and 4,4&rsquo-methylene diphenyl diisocyanate. Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Differential Thermal Analysis-Thermal Gravimetric Analysis, and elemental analysis were performed for both functionalized and non-functionalized particles to confirm the functionalization of the particles. The polyester polyol used in the production of polyurethane was synthesized from 1,4-butanediol and adipic acid (PE-PO-1), and phthalic anhydride (PE-PO-2). Molecular structure of the polyester polyols was confirmed by Fourier Transform Infrared Spectroscopy analysis and molecular weight of the polymers were determined by end group analysis. Then, the produced functionalized nano-particles and polyester polyols were used for producing polyurethane organic-inorganic hybrid materials. Furthermore, polyurethane polymer and polymer-nonfunctionalized boehmite organic-inorganic hybrids were also synthesized for property comparison. Hardness, impact resistance, scratch resistance, abrasion resistance, and gloss property of the samples were determined. It was observed that mechanical properties of organic-inorganic hybrid materials improved significantly. The hardness of the PU produced with PE-PO-1 increased from 82 to 98 Persoz, and the hardness of the PU produced with PE-PO-2 increased from 52 to 78 Persoz when one weight percentage functionalized boehmite was used. The impact resistance of the coatings was found to depend on the type of the polyols used in PU but not in the inorganic component. Therefore PE-PO-2 used PU has higher impact resistance than PE-PO-1 used PU. Scratch resistance of the coatings improved from 2B to 2H when using functionalized boehmite. Abrasion resistance of PUs produced with PE-PO-1 increased from 2 to 10 l/micrometer and abrasion resistance of PUs produced with PE-PO-2 increased from 12 to 20 l/micrometer by addition of functionalized boehmite.
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Koysuren, Ozcan. "Preparation And Characterization Of Conductive Polymer Composites, And Their Assessment For Electromagnetic Interference Shielding Materials And Capacitors." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609452/index.pdf.
Full textAbstract:
The aim of this study was to improve electrical properties of conductive polymer composites. For this purpose, various studies were performed using different materials in this dissertation. In order to investigate the effect of alternative composite preparation methods on electrical conductivity, nylon 6/carbon black systems were prepared by both in-situ polymerization and melt-compounding techniques. When compared with melt compounding, in-situ polymerization method provided enhancement in electrical conductivity of nylon 6 composites.
Furthermore, it was aimed to improve electrical conductivity of polymer composites by modifying surface chemistry of carbon black. 1 wt. % solutions of 3-Aminopropyltriethoxysilane and formamide were tried as chemical modifier, and treated carbon black was melt mixed with low-density polyethylene (LDPE) and nylon 6. According to electron spectroscopy for chemical analysis (ESCA), chemicals used for surface treatment may have acted as doping agent and improved electrical conductivity of polymer composites more than untreated carbon black did. Formamide was more effective as dopant compared to the silane coupling agent. In order to investigate electromagnetic interference (EMI) shielding effectiveness and dielectric properties of conductive polymer composites, 1, 2 and 3 wt. % solutions of formamide were tried as chemical modifier and treated carbon black was melt mixed with poly(ethylene terephthalate) (PET). Composites containing formamide treated carbon black exhibited enhancement in electrical conductivity, EMI shielding effectiveness and dielectric constant values compared to composites with untreated carbon black.
In order to enhance electrical conductivity of polymer composites, the selective localization of conductive particles in multiphase polymeric materials was aimed. For this purpose, carbon nanotubes (CNT) were melt mixed with polypropylene (PP)/PET. Grinding, a type of solid state processing technique, was applied to PP/PET/CNT systems to reduce the average domain size of blend phases and to improve interfacial adhesion between these phases. Grinding technique exhibited improvement in electrical conductivity and mechanical properties of PP/PET/CNT systems at low PET compositions.
To investigate application potential of conductive polymer composites, polyaniline (Pani)/carbon nanotubes (CNT) composites were synthesized and electrochemical capacitance performances of these systems, as electrode material in electrochemical capacitors, were studied. Polyaniline/carbon nanotubes composites resulted in a higher specific capacitance than that of the composite constituents. Pseudocapacitance behavior of Pani might contribute to the double layer capacitance behavior of nanotubes. Additionally, as an alternative to Pani/CNT systems, polyaniline films were deposited on treated current collectors and electrochemical capacitance performances of these electrode systems were investigated. The highest specific capacitance of polyaniline/carbon nanotubes composites was 20 F/g and this value increased to 35.5 F/g with polyaniline film deposited on treated current collector.
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Gunbas, Gorkem E. "Novel Donor-acceptor Type Polymers Towards Excellent Neutral State Green Polymeric Materials For Realization Of Rgb Based Electrochromic Device Applications." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12609002/index.pdf.
Full textAbstract:
Polymers having one of the three complementary colors (red, green, and blue) in the reduced state and high transmissivity in the oxidized state are key materials towards use in electrochromic devices and displays. Although many neutral state red and blue polymers were reported up to date, neutral state green polymeric materials appear to be limited. For potential application of electrochromic materials in display technologies, one should have to create the entire color spectrum and this can be only achieved by having materials with additive or subtractive primary colors in their neutral states. To obtain a green color there should be at least two simultaneous absorption bands. Although the neutral state color is of great importance, the transmittance in the oxidized state is crucial too. The materials having one of the three primary colors should also possess highly transmissive oxidized states in order to be used in commercial electrochromic device applications. Donor-acceptor molecules lead to lower band gap due to resonances that enable a stronger double bond character between the donor and acceptor units. The materials with low band-gaps produce cathodically coloring polymers due to the lower energy transition in the doped state. Moreover, donor-acceptor type materials commonly show two absorption maxima. Since donor-acceptor approach seems to be the key to the complex nature of producing these materials, novel donor-acceptor type polymers were synthesized, and electrochromic properties were investigated in detail.Additionally a solution-processable donor-acceptor type polymer was realized using method of introducing alkyl side chains in the polymer structures.
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Endres, Kevin J. "Mass Spectrometry Methods For Macromolecules: Polymer Architectures, Cross-Linking, and Surface Imaging." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1553096604194835.
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Wu, Haiyan. "Design and Development of New Chemistry for Biosensing." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1502459975409826.
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