Dissertations / Theses on the topic 'Polymers-applications'
To see the other types of publications on this topic, follow the link: Polymers-applications.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Polymers-applications.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Patil, Satish Amrutrao. "Ladder polymers for photonic applications." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972447490.
Full text
2
Lochab, Bimlesh. "Polymers for electro-optic applications." Thesis, University of Oxford, 2006. http://ora.ox.ac.uk/objects/uuid:34ac7813-b315-415c-ac8a-eac269c23432.
Full textAbstract:
Polymer based photovoltaic cells are being intensively investigated. In such cells three key processes need to occur; namely light absorption, charge separation of the exciton, and transport of the separated charges to the electrodes. Light absorption is reliant on the optical density of the polymer. In general charge separation is achieved by blending an electron acceptor with the polymer film. However, blending materials gives rise to potentially unreliable manufacturing and lifetime issues. This thesis describes the preparation of poly(l,4-phenylenevinylene) derivatives containing dipoles in which the process of charge separation can be achieved intramolecularly. The dipole was created with the use of electron donating alkoxy groups attached to the polymer backbone, and electron withdrawing nitro group attached to the fluorenyl side chains. These groups are believed to facilitate the dissociation of the photogenerated exciton, and potentially stabilise the holes and electrons that are formed when the exciton is separated. The fluorenyl side chains were attached to the polymer backbone via biphenyl or vinyl linkages. The polymers were primarily formed using the Gilch method and the conjugated polymers were obtained either via a soluble precursor route or directly from the monomer. The photophysical properties were studied for polymers with the fluorenyl side-chains as they were found to be more easily formed and stable. For poly[2-(7-nitro-9,9-dipropylfluorenyl)-5-(2'- ethylhexyloxy)-l,4-phenylenevinylene] it was found that the photoluminescence quantum yield dropped by a factor of eight relative to the polymer without the nitro group. It was further elucidated that this was due to the exciton being separated. Solar cells containing the polymers from this study showed modest performance.
3
Kishi, Mariko. "Synthetic polymers for ophthalmic applications." Thesis, Aston University, 1987. http://publications.aston.ac.uk/9721/.
Full textAbstract:
The contact lens represents a well-established important class of biomaterials. This thesis brings together the literature, mostly Japanese and American patents, concerned with an important group of polymers, `rigid gas permeable contact lens materials'. A comparison is made of similarities in the underlying chemical themes, centring on the use of variants of highly branched siloxy compounds with polymerizable methacrylate groups. There is a need for standard techniques to assess laboratory behaviour in relation to in vitro performance. A major part of the present work is dedicated to the establishment of such standardised techniques. It is apparent that property design requirements in this field (i.e. oxygen permeability, surface and mechanical properties) are to some extent conflicting. In principle, the structural approaches used to obtain high oxygen permeability lead to surface properties that are less than ideal in terms of compatibility with tears. PMMA is known to have uniquely good (but not perfect) surface properties in this respect; it has been used as a starting point in attempting to design new materials that possess a more acceptable compromise of transport and surface properties for ocular use. Initial examination of the oxygen permeabilities of relatively simple alkyl methacrylates, show that butyl methacrylate which has a permeability some fifty times greater than PMMA, represents an interesting and hitherto unexplored group of materials for ophthalmic applications. Consideration was similarly given to surface modification techniques that would produce materials having the ability to sustain coherent tear film in the eye without markedly impairing oxygen transport properties. Particular attention is paid to the use of oxygen plasma techniques in this respect. In conclusion, similar design considerations were applied to an extended wear hydrogel lens material in an attempt to overcome mechanical stability deficiencies which manifest themselves lq`in vivo' but not `in vitro'. A relatively simple structure modification, involving steric shielding of the amide substituent group, proved to be an effective solution to the problem.
4
Bogdanowicz, Krzysztof Artur. "Liquid Crystalline Polymers for Smart Applications." Doctoral thesis, Universitat Rovira i Virgili, 2015. http://hdl.handle.net/10803/321835.
Full textAbstract:
Polímers cristall-líquids (PCL) posseeixen propietats que són una combinació entre sòlids cristal·lins i fluids. Actualment, PCL que incorporen elements actius en l'estructura (pe, grups de foto-sensibles, dendrons, etc.) condueixen a un material selectivament sensible. S'informa que els polímers es poden aplicar en diversos sistemes pe com materials amb memòria de forma, sensors o pantalles foto-òptiques. Els nostres estudis se centren en dues aplicacions diferents: microcàpsules fotosensibles per a sistemes de lliurament controlat i les membranes autoacoblades conductores de protons per a la fotosíntesi artificial. La versatilitat i les propietats anisotrópicas de PCL, els fan com a candidats ideals per a nombrosos aplicacions intel·ligents. Per obtenir sistemes amb alliberament foto-activa, una família de copolímers, que conté alfa-estilbè i diferents espaiadors s'han dissenyat i sintetitzat. Alfa-estilbè és un mesogéno foto-actiu. Les microcàpsules basades d'alfa-metilestilbeno, amb vainillina en nucli, estaven preparats. Experiment d'alliberament amb i sense fotoirradiación va demostrar l'eficàcia d'aquest sistema. CLP d'estructura adequada per a auto-acoblament en una estructura columnar que podria ser efectiu en el transport de protons selectiu. Alineació homeotrópica de columnes en una membrana polimèrica permet aconseguir conductivitat de protons. Objectiu del nostre treball va ser: aconseguir estructures organitzades utilitzant poliamines modificades amb un mesógeno dendrític en posició lateral; preparació de membranes orientades usant aquests materials polimèrics; avaluar l'eficàcia de les membranes cap al transport de protons. Es van preparar membranes híbrides de ceràmica / poliamina. El material va mostrar alta conductivitat de protons selectiva i transport aigua-independent.Actualmente, PCL que incorporan elementos activos en la estructura (p.e., grupos de foto-sensibles, dendrones, etc.) conducen a un material selectivamente sensible. Se informa de que los polímeros se pueden aplicar en varios sistemas p.e. como materiales con memoria de forma, sensores o pantallas foto-ópticas. Nuestros estudios se centran en dos aplicaciones diferentes: microcápsulas fotosensibles para sistemas de entrega controlada y las membranas autoensambladas conductoras de protones para la fotosíntesis artificial. La versatilidad y las propiedades anisotrópicas de PCL, los hacen como candidatos ideales para numerosos aplicaciones inteligentes. Para obtener sistemas con liberación foto-activa, una familia de copolímeros, que contiene alfa-estilbeno y diferentes espaciadores se han diseñado y sintetizado. Alfa-estilbeno es un mesogéno foto-activo. Las microcápsulas basadas de alfa-metilestilbeno, con vainillina en núcleo, estaban preparados. Experimento de liberación con y sin fotoirradiación demostró la eficacia de este sistema. CLP de estructura adecuada para auto-ensamblaje en una estructura columnar que podría ser efectivo en el transporte de protones selectivo. Alineación homeotrópica de columnas en una membrana polimérica permite conseguir conductividad de protones. Objetivo de nuestro trabajo fue: lograr estructuras organizadas utilizando poliaminas modificadas con un mesógeno dendrítico en posición lateral; preparación de membranas orientadas usando estos materiales poliméricos; evaluar la eficacia de las membranas hacia el transporte de protones. Se prepararon membranas híbridas de cerámica/poliamina. El material mostró alta conductividad de protones selectiva y transporte agua-independiente.
Liquid Crystalline Polymers (LCPs) possess properties which are a combination of crystalline solids and fluids. Currently, LCPs which incorporate active elements into the structure (i.e. photo-sensitive groups, dendrons, etc.) lead to selectively sensitive material. It is reported, that those polymers can be applied in a variety of systems i.e. as memory-shape materials, sensors or photo-optical displays. Our studies are focused on two different applications: photosensitive microcapsules for controlled delivery systems and self-assembly proton-conducting membranes for artificial photosynthesis. The extreme versatility and the characteristic anisotropic properties of LCPs, make them the ideal candidates for numerous smart applications. To achieve systems with photo-triggered release, a family of copolymers which contained alpha-methylstilbene and different spacers were designed and synthesized. Alpha-methylstilbene is a well-known photo-active mesogenic group. Microcapsules based on alpha-methylstilbene containing vanillin as a core were prepared. Release experiment in the presence and the absence of photoirradiation proved the effectiveness of this system. LC polymers of proper structure self-assembly into a columnar structure which could be effective in selective proton transport. Homeotropic alignment of columns in a polymeric membrane allows to achieve proton-conductivity. Aim of our work was: achieving organized structures using polyamine modified with a dendritic mesogen in side position; preparing oriented membranes based on this polymeric materials;assessing the effectiveness of the prepared membranes toward proton transport. Hybrid ceramic/polyamine membranes were prepared. The new material showed high selective proton conductivity and water independent transport.
5
Inal, Sahika. "Responsive polymers for optical sensing applications." Phd thesis, Universität Potsdam, 2013. http://opus.kobv.de/ubp/volltexte/2014/7080/.
Full textAbstract:
LCST-type synthetic thermoresponsive polymers can reversibly respond to certain stimuli in aqueous media with a massive change of their physical state. When fluorophores, that are sensitive to such changes, are incorporated into the polymeric structure, the response can be translated into a fluorescence signal. Based on this idea, this thesis presents sensing schemes which transduce the stimuli-induced variations in the solubility of polymer chains with covalently-bound fluorophores into a well-detectable fluorescence output. Benefiting from the principles of different photophysical phenomena, i.e. of fluorescence resonance energy transfer and solvatochromism, such fluorescent copolymers enabled monitoring of stimuli such as the solution temperature and ionic strength, but also of association/disassociation mechanisms with other macromolecules or of biochemical binding events through remarkable changes in their fluorescence properties. For instance, an aqueous ratiometric dual sensor for temperature and salts was developed, relying on the delicate supramolecular assembly of a thermoresponsive copolymer with a thiophene-based conjugated polyelectrolyte. Alternatively, by taking advantage of the sensitivity of solvatochromic fluorophores, an increase in solution temperature or the presence of analytes was signaled as an enhancement of the fluorescence intensity. A simultaneous use of the sensitivity of chains towards the temperature and a specific antibody allowed monitoring of more complex phenomena such as competitive binding of analytes.
The use of different thermoresponsive polymers, namely poly(N-isopropylacrylamide) and poly(meth)acrylates bearing oligo(ethylene glycol) side chains, revealed that the responsive polymers differed widely in their ability to perform a particular sensing function. In order to address questions regarding the impact of the chemical structure of the host polymer on the sensing performance, the macromolecular assembly behavior below and above the phase transition temperature was evaluated by a combination of fluorescence and light scattering methods. It was found that although the temperature-triggered changes in the macroscopic absorption characteristics were similar for these polymers, properties such as the degree of hydration or the extent of interchain aggregations differed substantially. Therefore, in addition to the demonstration of strategies for fluorescence-based sensing with thermoresponsive polymers, this work highlights the role of the chemical structure of the two popular thermoresponsive polymers on the fluorescence response. The results are fundamentally important for the rational choice of polymeric materials for a specific sensing strategy.Als Reaktion auf bestimmte äußere Stimuli ändern bestimmte wasserlösliche Polymere reversibel ihren physikalischen Zustand. Dieser Vorgang kann mithilfe von Fluorophoren, die in die Polymerstrukturen eingebaut werden und deren Fluoreszenzeigenschaften vom Polymer¬zustand abhängen, detektiert werden. Diese Idee ist der Ausgangspunkt der vorliegenden Arbeit, die sich damit beschäftigt, wie äußerlich induzierte Änderungen der Löslichkeit solcher Polymere mit kovalent gebundenen Fluorophoren in Wasser in ein deutlich messbares Fluoreszenzsignal übersetzt werden können. Dazu werden photophysikalische Phänomene wie Fluoreszenz-Resonanz¬energie¬transfer und Solvatochromie ausgenutzt. In Kombination mit einem responsiven Polymergerüst wird es möglich, verschiedene Stimuli wie Lösungs¬temperatur oder Ionenstärke, oder auch Assoziation-Dissoziation Reaktionen mit anderen Makromolekülen oder biochemische Bindungs¬reaktionen über die Änderung von Fluorezenz¬farbe bzw. –Intensität autonom mit bloßem Auge zu detektieren. Unter anderem wurde ein wässriger ratiometrischer Temperatur- und Salzsensor entwickelt, der auf der komplexen supramolekularen Struktur eines thermoresponsiven Copolymers und eines thiophenbasierten konjugierten Polyelektrolyts beruht. Die Anbindung solvato¬chromer Fluorophore erlaubte den empfindlichen Nachweis einer Temperatur¬änderung oder des Vorhandenseins von Analyten. Komplexere Phänomene wie das kompetitive Anbinden von Analyten ließen sich hochempfindlich steuern und auslesen, indem gleichzeitig die Sensitivität dieser Polymeren gegenüber der Temperatur und spezifischen Antikörpern ausgenutzt wurde. Überraschenderweise wiesen die hier untersuchten thermoresponsiven Polymere wie poly-N-isopropylacrylamid (pNIPAm) oder poly-Oligoethylenglykolmethacrylate (pOEGMA) große Unterschiede bzgl. ihrer responsiven optischen Eigenschaften auf. Dies erforderte eine ausführliche Charakterisierung des Fluoreszenz- und Aggregationsverhaltens, unter- und oberhalb des Phasenübergangs, im Bezug auf die chemische Struktur. Ein Ergebnis war, dass alle drei Polymertypen sehr ähnliche temperaturabhängige makroskopische Absorptionseigenschaften aufweisen, während sich die Eigenschaften auf molekularer Ebene, wie der Hydratisierungsgrad oder die intermolekulare Polymerkettenaggregation, bei diesen Polymeren sehr unterschiedlich. Diese Arbeit zeigt damit anhand zweier sehr etablierter thermoresponsiver Polymere, nämlich pNIPAm und pOEGMA, das die chemische Struktur entscheidend für den Einsatz dieser Polymere in fluoreszenzbasierten Sensoren ist. Diese Ergebnisse haben große Bedeutung für die gezielte Entwicklung von Polymermaterialien für fluoreszenzbasierte Assays.
6
Wang, Jinfang. "Xanthine-imprinted polymers for decaffeination applications." Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431777.
Full text
7
Spampinato, Nicoletta. "Ferroelectric polymers for organic electronic applications." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0392/document.
Full textAbstract:
L'électronique organique représente une alternative réaliste aux technologies conventionnelles à base de silicium par le design, la synthèse et la mise en oeuvre des matériaux organiques fonctionnels dans des dispositifs légers et flexibles. Les matériaux organiques, tels que les petites molécules ou les polymères organiques, sont avantageux pour leur faible coût, leur flexibilité et leur facilité de traitement. Grâce aux avantages liés à l'utilisation de matériaux organiques, en termes économiques et de gain de temps, l'électronique organique est devenue un domaine innovant qui s'applique aux technologies de l'énergie, de l'environnement, de la santé, de l'information et de la communication.L'électronique organique est issue de la découverte de polymères dotés de fonctionnalités semi-conductrices. Cependant, il ne faut pas négliger une autre classe de polymères exceptionnels, les polymères ferroélectriques. La nature électroactive des polymères ferroélectriques, qui sont également pyroélectriques et piézoélectriques, combinés aux avantages intrinsèques des polymères, les a désignés comme éléments constitutifs d’une gamme étendue de dispositifs électroniques organiques.La famille de polymères ferroélectriques la plus connue est celle du poly(fluorure de vinylidène) P(VDF) et de son copolymère avec le trifluoroéthylène, P(VDF-co-TrFE). La récupération d'énergie, le stockage et la détection de données, principales applications de l'électronique organique, peuvent potentiellement tous être réalisés avec ces matériaux fonctionnels exceptionnels. La ferroélectricité étant une propriété dépendant de la structure, il est indispensable de mieux comprendre les relations réciproques entre la structure et les propriétés ferroélectriques finales afin d'améliorer les applications existantes des polymères ferroélectriques en électronique organique et de promouvoir l'introduction du P(VDF-co-TrFE) dans de nouvelles applications.P(VDF-co-TrFE) en tant que polymère semi-cristallin possède des propriétés cristallines sensibles au traitement thermique. Puisque seules les régions cristallines contribuent a le commutation électronique de la polarisation et non les amorphes, le degré de cristallinité est un facteur clé pour moduler les propriétés ferroélectriques. En autre, l'orientation des cristallites ainsi que la présence de défauts dans les cristallites sont des paramètres cruciaux qui jouent un rôle important dans la définition des performances finales des dispositifs dans lesquels P(VDF-co-TrFE) est incorporé. Tel est l'objectif de cette thèse: atteindre une compréhension exhaustive des relations traitement-structure-fonction qui serviront d'outil pour moduler les performances des dispositifs ferroélectriques.De plus, les applications potentielles de P(VDF-co-TrFE) en électronique organique sont explorées en examinant sa mise en oeuvre dans: (1) des capteurs médicaux à cathéter piézoélectrique destinés à mesurer la fonction cardiaque et éventuellement à détecter maladies cardiaques et (2) dispositifs électroniques dans lesquels P(VDF-co-TrFE) est mélangé avec le polymère poly(3-hexylthiophène) semi-conducteur, P3HT. Ce dernier a déjà été appliqué dans les diodes à mémoire ferroélectrique non volatile et l’utilisation potentielle dans le champ de l’organique photovoltaïque est exploréeOrganic electronics represent a realistic alternative to conventional silicon-based technologies through the design, synthesis and implementation of functional organic materials into light and flexible devices. Organic materials, such as small molecules or organic polymers, are advantageous for their low-cost, flexibility and easy processing. Thanks to the economical and timesaving advantages, organic electronics have emerged as an innovative field with application in energy, environment, health, information and communication technologies.Organic electronics originates from the discovery of polymers with semiconducting functionalities. However, one should not neglect another class of outstanding polymers, the ferroelectric polymers. The electroactive nature of ferroelectric polymers, which are also pyroelectric and piezoelectric, combined with the intrinsic advantages of polymers have designated them as constituent elements of a widespread range of organic electronic devices. The most well-known family of ferroelectric polymers is that of poly(vinylidene fluoride), P(VDF), and its copolymers with trifluoroethylene, P(VDF-co-TrFE). Energy harvesting, data storage and sensing, main applications of organic electronics, can potentially all be realised using these exceptional functional materials.Since ferroelectricity is a structure-dependent property an insight into the interrelations between structure and final ferroelectric properties is indispensable in order to improve existing applications of ferroelectric polymers in organic electronics and to promote the introduction of P(VDF-co-TrFE) in new application fields. P(VDF-co-TrFE) as semi-crystalline polymer possess crystalline properties which are sensitive to thermal treatment. Since only the crystalline regions contribute to ferroelectric switching and not the amorphous ones, the degree of crystallinity is a key factor to modulate the ferroelectric properties. Moreover, crystallites orientation as well as the presence of defects within the crystallites are crucial parameters playing an important role in defining the final performance of the devices in which P(VDF-co-TrFE) is incorporated.Herein stands the aim of this thesis: reach an exhaustive understanding of processing-structure-function relationships that will serve as tool to modulate ferroelectric devices performances.Going one step further, the potential applications of P(VDF-co-TrFE) in organic electronics are explored by investigating it in: (1) medical piezoelectric catheter sensors for measuring cardiac function and eventually for detecting cardiac disease and (2) electronic devices in which P(VDF-co-TrFE) is blended with the semiconducting polymer poly(3-hexylthiophene), P3HT. The latter has already been applied in non-volatile ferroelectric memory diodes and the potential use in organic photovoltaics is explored
8
Kuroda, Kenichi 1972. "Thermally responsive polymers and their applications." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29641.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2003.Vita.
Includes bibliographical references.
This thesis focuses on development of polymeric materials that can alter their functions according to temperature changes. We chose poly(N-isopropylacrylamide) (polyNIPA) as a platform, which phase-separates from water upon heating. The thermally responsive properties and applications of polyNIPA are introduced in Chapter One. In Chapter Two, we described the synthesis of polyNIPA gels with an imidazole comomoer and examined copper ion adsorption by the swollen (room temperature) and shrunken gels (60⁰C). The data analysis using a Langmuir adsorption isotherm indicates that the imidazole groups form 2:1 and 4:1 complexes with a copper ion in the swollen and shrunken gels, respectively, which suggests that thermal gel swelling and shrinking control the formation of multivalent Cu complexes by changing the distance among imidazole groups. In Chapters Three to Six, the synthesis of polyNIPA-conjugated polymer block copolymers and their applications are described. Non-ionic water-soluble poly(phenylene-ethynylene)s (PPEs) (Chapter Three) were used as conjugated polymer segments in the block copolymers. In a route to synthesis of the block copolymers, atom transfer radical polymerization (ATRP) and nitroxide-mediated radical polymerization (NMRP) of NIPA were developed. Incorporation of ATRP or NMRP initiators to the polymer ends of PPEs and the following polymerizations of NIPA were expected to provide tri-block copolymers with precise structures. The ATRP method produced pure polyNIPA with monodisperse and defined molecular weights (Chapter Four). However, endcapping of PPEs with an ATRP initiator ((α-chloroamide) was not successful due to its instability to PPE polymerization conditions (Chapter Five).
(cont.) On the other hand, PPEs could be endcapped with a NMRP initiator (a tert-butyl nitroxide derivative), and the following NMRP of NIPA provided the tri-block copolymers (Chapter Six), phase-separate from aqueous solutions upon heating due to the polyNIPA aggregation. In Chapter Six, we examined fluorescence resonance energy transfer (FRET) between a PPE-polyNIPA block copolymer and Rhodamine B (RhB) bound to polyNIPA. The RhB emission from the polymer precipitates produced by thermally induced phase-separation from the aqueous mixtures increased relative to that from the solutions, which indicates that thermal precipitation brought the PPE and RhB within the F6rster radius of each other and induced FRET between the PPE and RhB.
by Kenichi Kuroda.
Ph.D.
9
Maine, Elicia M. A. (Margaret Anne). "Future of polymers in automotive applications." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10509.
Full text
10
Svensson, Mikael. "Conducting redox polymers for battery applications." Thesis, Uppsala universitet, Strukturkemi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-415137.
Full textAbstract:
The near future will put a lot of demand on the increasing need for energy production and storage. Issues regarding the modern-day battery technology’s environmental benignity, safety and cost to sustain such demands thus serve as a huge bottleneck, necessitating the research into alternative electrochemical energy storage solutions. Conducting redox polymers are a class of materials which combines the concepts of conducting polymers and redox active molecules to work as fully organic electrode materials. In this work three conducting redox polymers based on 3,4-ethylenedioxythiopene and 3,4-propylenedioxythiopene (EPE) with hydroquinone, catechol and quinizarin pendant groups were investigated. The polymers were electrochemically characterized with regards to their ability to cycle protons (aqueous electrolyte) and cations (non-aqueous electrolyte), their kinetics and charge transport and as cathodes in a battery. In non-aqueous electrolyte, hydroquinone and catechol did not exhibit redox activity in a potential region where the backbone was conducting as they were not redoxmatched. Quinizarin showed redox-matching as concluded by in situ conductance and UV-vis measurements when cycling Na+, Li+, Ca2+ and Mg2+-ions in acetonitrile. Comparison of the kinetics revealed that the rate constant for Ca2+-ion cycling was several magnitudes larger than the rest, and galvanostatic charge/discharge showed that 90% of the polymer capacity was attainable at 5C. An EPE-Quinizarin cathode and metallic calcium anode coin cell assembly displayed output voltages of 2.4 V, and the presented material thus shows promising and exciting properties for future sustainable battery chemistries.
11
Martin, Benjamin Ryan. "Energy Harvesting Applications of Ionic Polymers." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/32024.
Full textAbstract:
The purpose of this thesis is the development and analysis of applications for ionic polymers as energy harvesting devices. The specific need is a self-contained energy harvester to supply renewable power harvested from ambient vibrations to a wireless sensor. Ionic polymers were investigated as mechanical to electrical energy transducers. An ionic polymer device was designed to harvest energy from vibrations and supply power for a wireless structural health monitoring sensor.The ionic polymer energy harvester is tested to ascertain whether the idea is feasible. Transfer functions are constructed for both the open-circuit voltage and the closed-circuit current. The impedance of the device is also quantified. Using the voltage transfer function and the current transfer function it is possible to calculate the power being produced by the device.Power generation is not the only energy harvesting application of ionic polymers, energy storage is another possibility. The ionic polymer device is tested to characterize its charge and discharge capabilities. It is charged with both DC and AC currents. An energy storage comparison is performed between the ionic polymers and capacitors. While the polymers performed well, the electrolytic capacitors are able to store more energy. However, the ionic polymers show potential as capacitors and have the possibility of improved performance as energy storage devices. Current is measured across resistive loads and the supplied power is calculated. Although the power is small, the ionic polymers are able to discharge energy across a load proving that they are capable of supplying power.Master of Science
12
wang, xin. "PEPTIDE LINKED POLYMERS FOR CADIOVASCULAR APPLICATIONS." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1340826344.
Full text
13
Perrot, Solène. "Semi-metallic polymers for thermoelectric applications." Thesis, Bordeaux, 2021. http://www.theses.fr/2021BORD0043.
Full textAbstract:
Les matériaux thermoélectriques (TE) ont le potentiel de convertir de grandes quantités de chaleur directement en électricité, et par conséquent de réduire la dépendance aux combustibles fossiles. En thermoélectricité, le concept d'un verre de phonons/cristal électronique est souvent utilisé pour décrire un matériau thermoélectrique idéal. Selon ce concept, un bon matériau TE devrait inhiber la conduction de phonons (ayant ainsi une faible conductivité thermique) tout en assurant efficacement une bonne conduction des porteurs de charges (conductivité électrique importante). Afin de quantifier l'efficacité des systèmes TE, la figure de mérite, ZT, est utilisée comme mesure de performance. Récemment, les polymères conducteurs ont gagné de l'élan dans la communauté TE pour des applications à température ambiante. Leur grand avantage est une conductivité thermique intrinsèquement faible à température ambiante (0.2-0.6 W.m-1K-1) qui est complétée par leur facilité de traitement et leur faible coût. Les films minces de dérivés de poly (3,4-éthylènedioxythiophène) (PEDOT) dopés avec des molécules de p-toluènesulfonate (Tos) peuvent présenter un ZT aussi élevé que 0,25 à température ambiante, soulignant ainsi le potentiel élevé de tels systèmes pour les applications futures. Dans cette thèse, nous nous sommes focalisés sur la compréhension des propriétés des films minces de PEDOT:Tos en jouant sur la méthode de polymérisation. Nous avons démontré que la conductivité électrique peut être améliorée en ajoutant des additifs dans la formulation du matériau. De plus, la concentration en p-toluènesulfonate est un paramètre permettant d’influencer la conductivité électrique sans modifier la valeur du coefficient Seebeck. Finalement, l’hybridation des précurseurs de PEDOT:Tos avec des copolymères à blocs a permis de concevoir des structures de PEDOT:Tos à l’échelle nanométriqueThermoelectric (TE) materials have the potential to convert vast amounts of waste heat directly into electricity, therefore reducing the dependence on fossil fuel. In thermoelectrics, the concept of a phonon glass/electron crystal is often used to describe an ideal thermoelectric material. According to this concept, a good TE material should inhibit the conduction of phonons (thus having a low thermal conductivity) while efficiently conducting electronic charge carriers (high electrical conductivity). In order to quantify the efficiency of TE systems, the figure of merit, ZT, is used as a measure of performance. Recently, conducting polymers have gained momentum in the TE community for applications at room temperature. Their great advantage is an intrinsically low thermal conductivity at room temperature (0.2-0.6 W.m-1K-1) that is complemented by their easy processability and their low cost. Thin films of poly(3,4-ethylenedioxythiophene) (PEDOT) derivatives doped with p-toluenesulfonate (Tos) molecules can exhibit a ZT as high as 0.25 at room temperature underlining the high potential of such systems for future applications. In this thesis, we focused on the understanding of PEDOT:Tos thin films properties by playing on the polymerization method. We demonstrated that the electrical conductivity can be improved by adding additives to the formulation of PEDOT:Tos materials. Moreover, the concentration of p-toluenesulfonate is an important parameter to tune the electrical conductivity without changing the Seebeck coefficient. Finally, the hybridization of PEDOT:Tos precursors with block copolymers allows us to design PEDOT:Tos nanostructures
14
Apaydin, Dogukan Hazar. "Electrochromic And Photovoltaic Applications Of Conjugated Polymers." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614481/index.pdf.
Full textAbstract:
Three new azobenzene containing conjugated monomers were designed and synthesized. Resulting monomers were characterized by means of 1H NMR and 13C NMR techniques. Monomers (E)-1,2-bis(4-(thiophen-2-yl)phenyl)diazene (M1), (E)-1,2-bis(4-(4-hexylthiophen-2-yl) phenyl) diazene (M2) and (E)-1,2-bis(2-fluoro-4-(4-hexylthiophen-2-yl)phenyl) diazene (M3) were electrochemically polymerized using cyclic voltammetry to give polymers P1, P2 and P3. The polymers were subjected to spectroelectrochemical and kinetic studies in order to obtain information about their elecrochromic characteristics. P1 and P2 were pale-yellow in their neutral states and blue in oxidized states while P3 showed multichromic property due to having polaron bands in visible region of the spectrum. Addition of fluorine atoms to the backbone of P3, lowered the LUMO level of P3 thus gained the polymer n-doping property.
In the second part of this thesis poly((9,9-dioctylfluorene)-2,7-diyl-(4,7-bis(thien-2-yl) 2-dodecyl-benzo[1,2,3]triazole)) (PFTBT) polymer was mixed with common electron acceptor Phenyl-C61-butyric acid methyl ester (PCBM) and used in organic solar cell applications. Active layers containing PFTBT and PCBM were spin casted on ITO coated substrates at varying rotational speeds to obtain active layer thicknesses having different values. Thickness of the active layer was optimized so was the efficiency of organic solar cells. As a result of this optimization study, efficiency of PFTBT containing organic solar cells were increased to 1.06% which is a higher value than previosly reported literature results.
15
Tse, Chui-wan. "Rhenium containing hyperbranched polymers for photonic applications." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38574512.
Full text
16
Rafati, Ali. "The analysis of polymers for biomedical applications." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/11914/.
Full textAbstract:
The aim of this work was to analyse the surface of biomedically relevant polymers with a range of surface sensitive techniques both in the interest of improving our knowledge of such polymeric delivery systems and the techniques used. Specifically time of flight- secondary ion mass spectrometry (ToF-SIMS) was a focus of this work complemented by a range of supportive surface and bulk analytical techniques. The new technique of X-ray photoelectron spectroscopy (XPS) depth profiling of organics was scrutinised through its application to a thin film blend of poly(l-lactic acid) (PLA) and the analgesic codeine in Chapter 3. Surface depletion of drug was observed in these films and was quantified for the first time with XPS. A multilayer model was created containing alternating layers of the codeine/PLA blend and biodegradable hydroxypropyl methylcellulose (HPMC) to test the application of SIMS to such formulations described in Chapter 4. Codeine was found to diffuse into a HPMC layer below it but not above due to a solubilisation of the bottom HPMC layer by the chloroform allowing small mobile codeine molecules to penetrate the layer below where the larger PLA chains were unable to. Interface widths observed when casting HPMC above a codeine/PLA layer was far broader than those observed when reversing layer order. This observation suggests HPMC is more sensitive to ion beam induced damage effects than PLA. The detailed characterisation of protein drug loaded polymeric microspheres was undertaken described in Chapter 5 revealing the discontinuous presence of surfactant at the surface and allowed for inferences to be made as to how the production process could be amended to tailor desired attributes. The work describes the thorough characterisation of biomedically relevant polymers with an array of surface sensitive techniques in the interest of improving the future description of such increasingly important formulations.
17
Tse, Chui-wan, and 謝翠雲. "Rhenium containing hyperbranched polymers for photonic applications." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38574512.
Full text
18
Pierre, Viera Marie. "New water-soluble polymers for surface applications." Thesis, Durham University, 2000. http://etheses.dur.ac.uk/4205/.
Full textAbstract:
The main objective of this work, which was the synthesis of water-soluble polymers for scale formation inhibition on stainless steel surfaces, has been achieved. Following an introduction and discussion of the background of the work (Chapter 1), the synthesis and characterisation of various monomers, norbomenes with alkylene ether side chains terminated by trialkyl ammonium salts, is described (Chapter 2). These monomers were polymerised to give water-soluble materials, as described in Chapter 3. The nature of the polymers involved and the development of special techniques for their characterisation is explained in Chapter 4. The amphiphilic water-soluble polymers prepared were used as additives in a detergent solution for scale inhibition tests. The variation in the structures of the polymers prepared allowed the study of the effects of different factors on scale inhibition, including the molecular weights of the polymers, the lengths of the alkylene ether side chains, and the nature of the trialkyl ammonium salt functionality. Most of the materials synthesised had an inhibiting effect on scale formation on the stainless steel substrate, in that treated surfaces allowed an easier cleaning of the samples. This study allowed the identification of a polymer structure showing good properties for scale inhibition, which may provide a lead for future development.
19
Noimark, Sacha M. "Light-activated antimicrobial polymers for healthcare applications." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1470179/.
Full textAbstract:
This thesis details the development of potent light-activated antimicrobial silicone polymers for use in healthcare environments. Upon illumination, these polymers induce the lethal photosensitisation of bacteria through the generation of a range of reactive oxygen species at the polymer surface, initiating a non-site specific attack against bacteria in the vicinity. Activation of the antimicrobial technology developed was achieved using laser illumination (635 nm) and UVA illumination for medical device applications, or white hospital lighting conditions for hospital touch surface applications. Moreover, for the first time, some photobactericidal materials developed also demonstrated strong antimicrobial activity through an additional dark-activated mechanism. Antimicrobial polymers were developed through use of a swell-encapsulation-shrink strategy to incorporate photosensitiser dyes such as methylene blue and crystal violet, in addition to a range of nanoparticles including 2 nm gold nanoparticles, zinc oxide nanoparticles and titania nanoparticles, into medical grade silicone. Specifically, the photobactericidal silicone polymer systems detailed in this thesis are: (i) crystal violet-coated, methylene blue and 2 nm gold nanoparticle-encapsulated silicone for both medical device and hospital touch surface applications, (ii) crystal violet-coated, zinc oxide nanoparticle-encapsulated silicone for hospital touch surface applications and (iii) oleic acid-functionalised titania or gold-doped titania nanoparticle-encapsulated silicone for medical device or hospital touch surface applications (in combination with a suitable light delivery system). The materials were characterised using techniques including: light microscopy, fluorescence microscopy, transmission electron microscopy, UV-Vis absorbance spectroscopy, X-ray photoelectron spectroscopy, time-resolved electron paramagnetic resonance spectroscopy and time-resolved detection of near infrared singlet oxygen phosphorescence (∼ 1270 nm). Functional testing indicated that these materials were suitable for targeted applications and demonstrated strong material photostability and dye-polymer stability under aqueous conditions. The polymers demonstrated strong light-activated antimicrobial activity when tested against key Gram-positive and Gram-negative bacteria associated with hospital-acquired infections including Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli, with > 4 log reductions in viable bacterial numbers observed. Significant antimicrobial activity was also noted under dark conditions. It is anticipated that the potent antimicrobial technology detailed in this thesis could ultimately be used in both medical device and hospital touch surface applications, to reduce bacterial surface colonisation and the associated incidence of hospital-acquired infections.
20
Amara, John Paul. "Polymers for electronics and chemical sensing applications." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36256.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2006.Vita.
Includes bibliographical references.
The incorporation of molecular structures such as shape persistent molecular frameworks, strong hydrogen bond donor groups or perfluoro-alkyl groups can result in considerable gains in the performance of some established polymeric materials. This dissertation details the synthesis and properties of polymers that demonstrate such types of functionality for emerging electronics and chemical sensing applications. In Chapter 1, we present a general introduction to organic electronic materials and chemical sensory technologies. This chapter introduces many of the important principles that are explored throughout the rest of the text. In Chapters 2 and 3, we develop some novel polymeric materials for organic electronics applications. In Chapter 2, the development of several insulating polymers that demonstrate very high porosity in the solid state is discussed. The high porosity is provided by rigid three-dimensional frameworks, which present large amounts of internal free volume. In Chapter 3, we present the development of conducting polymeric materials that present rigid iptycene frameworks. These materials are prepared through an electro-chemical deposition process.
(cont.) In Chapter 4, we find that the performance of an established conjugated polymer-based chemical sensory technology can be enhanced through the employment of pendant hexafluoroisopropanol groups that function as strong hydrogen bond-donating sorbant elements for weakly-binding analytes. In Chapter 5, we demonstrate that these hexafluoroisopropanol groups can be incorporated into a host of polymeric materials through a unique solid-state functionalization step that employs the reactive chemical hexafluoroacetone. These materials may be useful for analyte pre-concentration applications. Finally, in Chapter 6, we develop new, highly-luminescent conjugated polymers for future organic light-emitting diode-based display applications using hexafluoroacetone as a source of fluorination for the polymers. These materials demonstrate greater photo-oxidative stability that may extend their lifetimes in device applications.
by John Paul Amara.
Ph.D.
21
Long, James. "Protein containing porous polymers for biocatalytic applications." Thesis, Liverpool John Moores University, 2005. http://researchonline.ljmu.ac.uk/5660/.
Full textAbstract:
Over the last twenty years there has been a great deal of research conducted into the use of enzymes as catalysts for reactions conducted in non-aqueous media. Not only has it been shown that enzymes can function effectively in organic media, but also that the range of reactions that they can catalyse has been vastly increased. The major disadvantages associated with non-aqueous enzymatic catalysis are relatively slow reaction rates compared to traditional aqueous catalysis, poor enzyme stability towards polar organic solvents and protein agglomeration, which leads to reduced efficiency, making recovery and reuse of the enzyme very difficult. Immobilisation of the enzyme on a suitable support material has been shown to be an effective method in overcoming these problems. This study examined several different methods for immobilising a-chymotrypsin on novel support materials. The catalytic activities of the preparations were assayed by following the transesteriflcation reaction between N-acetyl-L-tyrosine ethyl ester (A TEE) and propan-l-ol by high performance liquid chromatography (HPLC). Immobilised enzyme activities were compared to those obtained for simple unsupported lyophilised preparations of a-chymotrypsin. Uniform porous poly(acrylamide) beads were loaded with various quantities of enzyme via an adsorption procedure. Catalytic activity was measured over a wide range of thermodynamic water activities and was found to be similar to the lyophilised preparations. However, the immobilised enzyme was shown to be more resistant to changes in pH and temperature, and could easily be recovered from the reaction mixture and reused. Design of experiment methodology was employed to optimise support matrices constructed from six component materials. The enzyme was immobilised via a noncovalent entrapment method. The best composites prepared displayed a fifty-fold increase in catalytic activity and a three-fold increase in mechanical strength relative to the equivalent a-chymotrypsin controls. These materials could be reused more than ten times whilst still retaining useful catalytic activity. Porous poly(acrylamide) monoliths containing entrapped a-chymotrypsin were synthesised using a novel carbon dioxide high internal phase emulsion templating technique. The effects of enzyme loading, carbon dioxide pressure and monomer to crosslinker ratio were examined. The corresponding enzyme activity of all the emulsion templated materials was shown to be higher than for the unsupported lyophilised preparations, with the best materials exhibiting a ten-fold increase in activity. Multipoint covalent enzyme immobilisation was also studied. The structure of the enzyme was first modified so as to include a polymerisable functionality. This modified enzyme was then dissolved in organic solvents via the formation of ion-pairs with various anionic surfactants. It was shown that the enzyme remained in solution when transferred from organic solvents to a mixture of monomers. The dense gas porogen R134a was then added to the solution of enzyme in monomer, prior to the initiation of a polymerisation reaction. The resulting crosslinked enzyme-containing polymers were shown to possess useful catalytic activity.
22
Treharne, Andrew J. "Development of biocompatible polymers for ocular applications." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/344289/.
Full textAbstract:
Age-related macular degeneration (AMD) is the largest cause of blindness for those over 65 in the developed world. There is currently no treatment for the retinal cellular loss associated with the disease. One potential therapy is to implant retinal stem cells into the eye using a biodegradable polymer scaffold. Blends of the biodegradable polymers, poly(L-lactic acid) (PLLA) and poly(D,L-lactic-co-glycolic acid) (PLGA) have been formulated into microspheres. The influence of changing processing parameters on the size and morphology of the microspheres has been studied. A human retinal pigment epithelial (APRE-19) cell line was shown to adhere, survive and proliferate on the surface of the microspheres in vitro. Assays have demonstrated that the nature of the blend influenced cell behaviour. Transplantation of retinal pigment epithelial (RPE) cells on a supportive matrix has also been investigated as a therapy for AMD. In view of AMD related pathology of the native RPE support, Bruch’s membrane (BM), transplanted RPE cells require a scaffold to reside on. Copolymers based on methyl methacrylate (MMA) and poly(ethylene glycol) methacrylate (PEGM) have been synthesised and chemically modified at the PEG terminus. These polymers were subsequently manufactured into a fibrous scaffold using an electrospinning technique and investigated as an artificial BM. RPE cells were shown to attach and proliferate successfully on the surface of the fibrous scaffold in vitro. Cell adhesion was significantly enhanced on scaffolds with the PEG chain terminus modification. Significantly less apoptotic cell death was also observed on these surfaces. The diffusion properties of these artificial membranes have also been investigated. In addition, the novel gelation of the produced copolymers under certain conditions has been studied
23
Li, Bin. "Molecularly imprinted polymers for applications in cosmetology." Thesis, Compiègne, 2013. http://www.theses.fr/2013COMP2083.
Full textAbstract:
Un polymère à empreintes moléculaires (MIP) est un récepteur synthétique supramoléculaire, un matériau possédant des cavités pouvant reconnaître spécifiquement une molécule cible. Il est synthétisé en mettant en contact la molécule cible, avec un mélange de monomères fonctionnels et réticulants qui permettent d'obtenir un réseau polymérique tridimensionnel rigide. L'élimination de la molécule empreinte laissera des sites vides complémentaires de cette dernière. Ces cavités sont maintenant capables de la recapturer spécifiquement. Ces polymères sont utilisés dans les domaines tels que l’extraction en phase solide, la chromatographie d’affinité, la catalyse enzymatique, les biocapteurs et la vectorisation des médicaments. Bien que le concept des MIPs a pour origine les travaux réalisés sur des matériaux sol-gel imprimés dans les années 1930, ces derniers sont restés dans l’ombre jusqu’à l'introduction de polymères organiques imprimés plus versatiles. Par rapport aux MIPs organiques, les MIPs sol-gel présentent quelques avantages comme une plus grande stabilité thermique, une meilleure compatibilité avec l'eau et une plus grande porosité. Dans cette thèse, nous avons développé des MIPs organiques et des MIPs sol-gel pour leur application en cosmétologie et pour la vectorisation de médicaments. Dans la première partie, nous présentons des MIPs pouvant adsorber d’une façon spécifique l’acide oléique (OA), un biomarqueur de l’état pelliculaire sur le cuir chevelu. Pour la préparation des MIPs organiques, nous avons employé plusieurs monomères basiques dont l’acryloylaminobenzamidine (AB), que nous avons tout spécialement synthétisé. Tous les MIPs pouvaient lier l’OA mais beaucoup d’interaction non-spécifique était observé. D’autre part, les MIPs sol-gel présentaient une bonne reconnaissance spécifique et une capacité élevée pour OA; par exemple, un MIP de composition OA:APTES:TEOS = 1:1.6:1.7 pouvait adsorber 625 μmol.g-1 de OA dans le sébum artificiel. Des tests pour capturer l’OA sur le stratum corneum et la peau reconstruite (Episkin) ont également été effectués. La pénétration de l’OA sur les deux types de peau était plus faible en présence de MIP que de NIP. Les MIPs comme matériaux désodorisants font l’objet de la deuxième partie de cette thèse. Des MIPs pouvant adsorber les précurseurs de molécules malodorantes comme les conjugués glutamine des acides (E)-3-méthyl-2-hexénoïque (3M2H) et 3-hydroxy-3-méthyl-hexanoïque (3H3MH) ont été préparés. Le N-hexanoyl glutamine et le N-hexanoyl glutamate ont été utilisés comme template. Nous observons que le MIP synthétisé avec AB comme monomère fonctionnel possède la plus grande capacité d'adsorption pour le N-hexanoyl glutamine, ainsi que pour les précurseurs glutamines des molécules malodorantes. Des résultats préliminaires et très prometteurs ont également été obtenus dans la sueur. La dernière partie de cette thèse concerne des MIPs pour la vectorisation de médicaments. L'acide salicylique (SA) est un médicament efficace utilisé dans le traitement de l’acné. Des MIPs organiques et sol-gel contre SA ont été synthétisés. Les MIPs sol-gel ont une plus grande capacité d’adsorption, 180 μmol.g-1, que les MIPs organiques et ils lient le SA sept fois plus que le NIP. Les tests de relargage du SA ont été effectués dans plusieurs milieux, avec la plus grande efficacité dans l’eau pure. En conclusion, les applications de MIPs en cosmétologie et en vectorisation de médicaments ont étés étudiés. Nos résultats montrent que les MIPs sol-gel sont les plus appropriés pour ce type de travailMolecularly imprinted polymers (MIPs) are tailor-made synthetic receptors possessing specific cavities for a given target molecule. They are produced by introducing, into the polymer precursors, guest molecules that act as templates at the molecular level. Interacting and cross-linking monomers are then copolymerized to form a cast-like shell. After removal of the template, cavities complementary to the template in size, shape and position of functional groups are revealed in the polymer, which can now specifically bind the template. Thanks to these specific molecular recognition properties, MIPs have found applications in areas like bio sensors, solid phase extraction, affinity chromatography, catalysis, and drug delivery. Although the MIP concept originated from imprinted silica in the 1930s, imprinted sol-gel materials received little attention afterwards due to the introduction of the more versatile organic polymers as imprinting matrix. However, compared to organic polymers, sol-gels possess higher thermal stability, better water compatibility and larger inner surface area. There have been many applications to biomolecules in aqueous conditions with sol-gel imprinting materials. In this thesis, we have developed organic and silica sol-gel MIPs for applications in cosmetics and drug delivery. MIPs able to adsorb the dandruff-inducing molecule oleic acid (OA) were produced via both the organic and inorganic routes. In the organic MIPs synthesis, different positively charged monomers were used, one of which, acryloyl aminobenzamidine, was specifically synthesized. Although some binding of oleic acid was obtained, specificity and capacity of these polymers were not satisfying. Sol-gel MIPs, on the other hand, exhibited good specific recognition and high binding capacity for OA. A MIP of the composition OA:APTES:TEOS= 1:1.6:1.7 yielded a capacity of 625 μmol.g-1 in artificial sebum. Furthermore, tests were carried out to capture OA on stratum corneum and reconstructed skin (Episkin). Less penetration of OA was observed in the presence of a MIP than with a non-imprinted control polymer. Deodorant materials are another topic of this thesis. MIPs that are able to adsorb certain precursors of odorant molecules, the glutamine conjugates of (E)-3-methyl-2-hexenoic acid (3M2H) and 3-hydroxy-3-methyl-hexanoic acid (3H3MH) were prepared. N-hexanoyl glutamine and N-hexanoyl glutamate were used as templates. After optimization of the MIP composition, we found that MIPs synthesized with acryloyl aminobenzamidine as functional monomer had the highest adsorption capacity for N-hexanoyl glutamine, and also recognised the glutamine targets of 3M2H and 3H3MH. Some preliminary promising binding results were obtained in artificial sweat. The third part of this work concerns a drug delivery MIP. Salicylic acid (SA) is a drug used to treat acne. SA-imprinted polymers were prepared via both organic imprinting and the sol-gel process.Compared to organic MIPs, sol-gel MIPs have a higher capacity, 180 μmol.g-1, and 7 times higher binding than to a non-imprinted control polymer was observed. Release tests were carried out in different aqueous media, the most efficient drug release was observed in pure water. In conclusion, applications of molecularly imprinted polymers for cosmetics and drug delivery have been investigated. Our results demonstrate the great potential of in particular sol-gel MIPs for these purposes
24
Cartwright, Luke. "Donor-acceptor conjugated polymers for optoelectronic applications." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/12054/.
Full textAbstract:
The development of renewable energy is of paramount importance if scientists are to mitigate the enhanced greenhouse effect and dwindling supplies of fossil fuels. Solar energy is believed to be the largest carbon-neutral energy source available with the sun producing vast quantities of energy every second. Current inorganic photovoltaic systems that are available have numerous limitations and shortcomings associated with them. Thus, research into an alternate, cost-efficient photovoltaic device that efficiently harvest a large portion of the incident solar spectrum has resulted in scientists focussing on so-called third generation photovoltaics. Organic photovoltaic devices, which use semiconducting conjugated polymers and fullerene derivatives in the active layer, are an example of third generation devices. Organic photovoltaic devices possess numerous advantages over their inorganic counterparts including: reduced embodied energy, increased flexibility, abundant materials for fabrication and better operation at lower light intensity levels. However, currently they are not as efficient as inorganic devices. The performance of organic photovoltaic devices is influenced by the chemical structure of the semiconducting conjugated polymer. Specifically, the optical band gap, frontier energy levels, charge carrier mobility and solubility are determined by the chemical structure. Copolymerising electron-donating monomers with electron-withdrawing substituents in a so called donor-acceptor (D-A) arrangement has proven to be an effective method in producing conjugated polymers that have high efficiencies when fabricated into organic photovoltaic devices. Chapter II and Chapter III ascertained that attaching fluorine substituents to the benzothiadiazole moieties resulted in a decreased molecular weight. This phenomenon continued to occur when larger alkyl chains were attached to the conjugated backbone. Furthermore, fluorination of the benzothiadiazole unit yielded blue shifted absorption maxima. However, it did deepen the HOMO level of the polymer resulting in increased oxidative stability. Additionally, changing the fluorene donor for the planar, fully aromatic carbazole moiety was successful in lowering the optical band gap. In chapter IV, the donor portion of the conjugated polymer was changed for a triisopropylsilylacetylene functionalised anthracene unit. Previous work within the Iraqi group has shown that the anthracene unit to be a weak donor. Incorporation of the anthracene units resulted in a narrower optical band gap despite the low molecular weights of the polymers. Furthermore, the weak donating properties of the anthracene donor unit yielded deep HOMO levels. In Chapter V, the benzothiadiazole moieties used as acceptor units in Chapter IV were substituted for a thieno[3,4-c]pyrrole-4,6-dione acceptor; an extremely planar compound with strong electron withdrawing properties. Various solubilising groups were attached to the thieno[3,4-c]pyrrole-4,6-dione acceptor to ascertain the impact solubilising chains has upon the physical properties of the polymer. However, it was discovered the steric clash between the bulky triisopropylsilylacetylene groups and the chains attached to the thieno[3,4-c]pyrrole-4,6-dione acceptor resulted in unfavourable backbone twisting. Thus, the polymers displayed wide optical and electrochemical band gaps despite having a high molecular weight. The amorphous nature of these polymers was confirmed with power X-ray diffraction. In chapter VI, the thieno[3,4-c]pyrrole-4,6-dione acceptor unit was changed for diketopyrrolopyrrole acceptor unit. It was hypothesised that the increased planarity of this molecular, relative to thieno[3,4-c]pyrrole-4,6-dione would minimse steric clash between alkyl chains and increase planarity. This hypothesis was proved correct when all polymers sysnthesised in this chapter displayed extremely narrow optical and electrochemical band gaps. Furthermore, powder X-ray diffraction showed the polymers adopted a semi-crystalline conformation, which should, in theory, improve charge transportation. Finally, in Chapter VII the triisopropylsilylacetylene functionalised donor was polymerised with either a fluorinated or non-fluorinated quinoxaline acceptor unit. Relative to the non-fluorinated polymer, the fluorinated polymer displayed a blue-shifted absorption maximum and wider optical and electrochemical band gaps. However, the fluorinated polymer adopted a more crystalline structure, a consequence of enhanced π-π stacking and intermolecular interactions brought about by the incorporation of fluorine.
25
Volodin, Boris Leonidovich 1965. "Design, physics, and applications of photorefractive polymers." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282188.
Full textAbstract:
The subject of this dissertation is design, physics, and applications of organic photorefractive polymers which are a recently discovered new class of multifunctional polymeric composites suitable for real-time holographic recording. Design principles of amorphous guest-host photorefractive polymers are described, and their performance is investigated. Also, the use of these materials as recording media in dynamic holographic applications is evaluated. Diffraction efficiency of η ∼ 86%, limited only by absorption and reflection losses, two-beam coupling net gain coefficient of Γ = 200 cm⁻¹, and light-induced refractive index modulations as high as Δn =7x10⁻³ are demonstrated. Hologram growth rates of the order of 500 ms are observed with recording light intensities > 10 mW/cm² using either low-power laser diodes (675 nm) or a HeNe laser (633 nm). The materials have been synthesized that show good sensitivity in red and near-infrared part of the light spectrum. Physical mechanisms leading to high performance of photorefractive polymeric composites and the influence of the polymer composite structure on optical performance are investigated. The experimental results are compared with a phenomenological model based on Kukhtarev's equations. Experiments showing possible applications of PR polymers, such as dynamic time-average interferometry and document security verification are demonstrated.
26
Nimmagadda, Alekhya. "Design, Synthesis, Applications of Polymers and Dendrimers." Scholar Commons, 2017. https://scholarcommons.usf.edu/etd/7430.
Full textAbstract:
WHO has reported that antibiotic resistance is the third major cause of human death all over the globe. Recent study, has focused on the development of new antibacterial resistance drugs. Herein, we tried to synthesis a series of polymers that can mimic the HDPs. HDPs can target the bacterial cell membrane and they have less chances to develop bacterial resistance. We synthesized the amphiphilic polycarbonates that are highly selective to Gram-positive bacteria, including multidrug resistant pathogens. The membrane disruption activity of these polymers was proved by fluorescence and TEM studies and the drug resistance study showed that the polymers don’t develop bacterial resistance. In order to further design the molecules that can target a broad spectrum of bacteria, we have designed a series of lipidated dendrimers that can target the Gram-positive and Gram-negative bacteria. These dendrimers mimic the HDPs and target the bacterial cell membrane. Dendrimers are reported to inhibit the formation of bacterial biofilm which makes them promising for their future development of antibiotic agents.
Apart from the synthesis of polymers and dendrimers as antibacterial agents, we have designed a series of small molecular antibacterial agents that are based on the acylated reduced amide scaffold and small dimeric cyclic guanidine derivatives. These molecules display good potency against a panel of multidrug-resistant Gram-positive and Gram-negative bacterial strains. Meanwhile, they also effectively inhibit the biofilm formation. Mechanistic studies suggest that these compounds kill bacteria by compromising bacterial membranes, a mechanism analogous to that of host-defense peptides (HDPs). Lastly, we also demonstrate that these molecules have excellent in vivo activity against MRSA in a rat model. This class of compounds could lead to an appealing class of antibiotic agents combating drug-resistant bacterial strains.
27
Cocchi, Davide <1989>. "Nanofibrous-structured polymers and their engineering applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amsdottorato.unibo.it/9666/1/cocchi_davide_tesi.pdf.
Full textAbstract:
Monolithic materials cannot always satisfy the demands of today’s advanced requirements. Only by combining several materials at different length-scales, as nature does, the requested performances can be met. Polymer nanocomposites are intended to overcome the common drawbacks of pristine polymers, with a multidisciplinary collaboration of material science with chemistry, engineering, and nanotechnology. These materials are an active combination of polymers and nanomaterials, where at least one phase lies in the nanometer range. By mimicking nature’s materials is possible to develop new nanocomposites for structural applications demanding combinations of strength and toughness.
In this perspective, nanofibers obtained by electrospinning have been increasingly adopted in the last decade to improve the fracture toughness of Fiber Reinforced Plastic (FRP) laminates. Although nanofibers have already found applications in various fields, their widespread introduction in the industrial context is still a long way to go.
This thesis aims to develop methodologies and models able to predict the behaviour of nanofibrous-reinforced polymers, paving the way for their practical engineering applications. It consists of two main parts. The first one investigates the mechanisms that act at the nanoscale, systematically evaluating the mechanical properties of both the nanofibrous reinforcement phase (Chapter 1) and hosting polymeric matrix (Chapter 2).
The second part deals with the implementation of different types of nanofibers for novel pioneering applications, trying to combine the well-known fracture toughness enhancement in composite laminates with improving other mechanical properties or including novel functionalities. Chapter 3 reports the development of novel adhesive carriers made of nylon 6,6 nanofibrous mats to increase the fracture toughness of epoxy-bonded joints. In Chapter 4, recently developed rubbery nanofibers are used to enhance the damping properties of unidirectional carbon fiber laminates. Lastly, in Chapter 5, a novel self-sensing composite laminate capable of detecting impacts on its surface using PVDF-TrFE piezoelectric nanofibers is presented.
28
Basto, M. José Ricardo. "Mechanical characterization of aged recycled polymers and applications." Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2649.
Full textAbstract:
Thesis (M.S.)--West Virginia University, 2002.Title from document title page. Document formatted into pages; contains xxv, 217 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 163-164).
29
Kellam, Edwin Clay. "The synthesis and applications of phosphazene-containing polymers." Full text available online (restricted access), 2001. http://images.lib.monash.edu.au/ts/theses/Kellam.pdf.
Full text
30
Forsberg, Julia. "Derivatisation of Betulin for industrial applications : - Green polymers." Thesis, Umeå universitet, Kemiska institutionen, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-66951.
Full text
31
Schmit, Jean-Paul. "Novel polymers for applications in light emitting diodes." Thesis, Lancaster University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322867.
Full text
32
Al-Eid, Manal Ali. "Redox-active molecules and polymers with photovoltaic applications." Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/4657/.
Full textAbstract:
The study presented in this thesis provides details regarding the synthesis and characterization of different redox active molecules which can be applied to form the active layer of photovoltaic devices. For example in chapter two, star-shaped thiophene based molecules are described and their electronic and optical properties have been investigated. In chapter three, oligomers featuring bipyridinium units with different thienyl moieties have been successfully synthesized. Preliminary electropolymerization studies are achieved. In chapter four, two different series of powerful push-pull systems containing dimethyaniline DMA moieties as a strong donating group and TCNE or TCNQ as electron accepting groups have been prepared. These series feature quinone and oligothiophene units as supporting acceptor and donor unit. In chapter five, two different series of powerful organic dyes that could improve the efficiency of DSSCs by modulating the absorption of light towards the near-IR region are achieved. The influence of π-conjugated spacers on the optical and physical properties of synthesized dyes has been investigated. Preliminary DSSCs have been fabricated from some of these systems and their properties have been compared to dye N719.
33
Harismah, Kun. "Development of New Carbazole Polymers for LED Applications." Thesis, University of Sheffield, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.500291.
Full text
34
Yin, Xunqian. "Modification of electrostrictive polymers and their electromechanical applications." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0041/document.
Full textAbstract:
Les polymères électroactifs (PAE), sont des matériaux permettant de réaliser une conversion entre l'énergie électrique et mécanique. L'objet de ce travail est de proposer des procédés de modifications des terpolymères électrostrictifs par voies composites basés sur différentes approches dans le but d’améliorer les performances électromécaniques et de développer des applications à partir de ces matériaux modifiés. Dans un premier temps, un nano-composite à base de terpolymère et de noir de carbone a été préparé pour améliorer la permittivité diélectrique. Dans un deuxième temps, sur la base de la nature hétérogène de terpolymère semi-cristallin ainsi que du rôle important que la polarisation interfaciale joue sur la réponse diélectrique et électromécanique, une faible quantité d’agent plastifiant (bis (2-ethylhexyl) phalate (DEHP)) a été introduite dans le terpolymère électrostrictif afin de former un composite tout organique permettant l'amélioration des performances électromécaniques. Enfin, l’utilisation de ces matériaux modifiés dans deux applications spécifiques a été étudiée: La récupération de l'énergie mécanique et une pompe microfluidique sans valveElectroactive polymers (EAPs), which can realize the conversion between electrical and mechanical energy, have been emerging as one of the most interesting smart materials in the past two decades due to their low density, excellent mechanical properties, ease of processing, low price and potential applications in the fields of sensors, actuators, generators, biomimetic robots and so on. The object of this work is to modify electrostrictive terpolymers with different approaches to improve the electromechanical performances and to develop some applications based on modified terpolymers. Firstly, an organic/inorganic (terpolymer/carbon black) nanocomposite was prepared to improve the dielectric permittivity based on the percolation theory. Secondly, based on the heterogeneous nature of semi-crystalline terpolymer and the important role that interface polarization plays for dielectric and electromechanical response, small molecular plasticizer bis(2-ethylhexyl) phalate (DEHP) was introduced into electrostrictive terpolymer to form an all-organic polymer composite with improved electromechanical performances. Finally, two applications including mechanical energy harvesting and microfluidic pump based on DEHP modified terpolymers were investigated
35
Beldon, Patrick John. "New synthetic methods & applications for coordination polymers." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708056.
Full text
36
Benzeval, Ian. "Development of responsive polymers for drug delivery applications." Thesis, University of Bath, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.500696.
Full textAbstract:
In this thesis, glucose responsive hydrogels based on cross-linked dextran molecules were studied to determine the diffusion rate of an insulin analogue. Investigations of the interaction between concanavalin A and dextran, both in free solution and in the form of glucose responsive hydrogels were conducted. The free solution results have shown that there is an increase of association constant between concanavalin A and dextran when the molecular mass of the dextran is increased. Free solution viscometric tests have shown that increasing the molecular mass or the concentration of the dextran increases the viscosity. The hydrogels have been shown to form for dextrans of molecular mass 43kD or greater. Experiments conducted with hydrogel membranes in a diffusion cell have shown that the batch to batch reproducibility of hydrogel transport properties is low. However, clear evidence of glucose enhanced transport was obtained and these results were compared with predictions obtained from a theoretical model of gel permeability that accounts for competitive displacement of affinity cross links. Oscillatory rheological tests of gelation mixtures which showed an increase in complex viscosity at the gel point with increasing molecular mass of dextran were in agreement with empirical observations that gels formed from the highest molecular mass dextrans were more physically robust and easier to handle. Swelling rate experiments have shown that the rate of hydration of a hydrogel in the presence of glucose is decreased due to the osmotic pressure of the glucose. This work has shown that the multivalent nature of concanavalin A may not be a necessary pre-requisite for this type of hydrogel due to spatial constraints decreasing the number of potential affinity bonds per tetramer. In-house production of more tightly defined dextrans might be expected to reduce heterogeneity and improve the reproducibility of this type of hydrogel membrane.
37
Dai, Xiaoshu. "Synthesis and Processing of Polymers for Biomedical Applications." Digital WPI, 2010. https://digitalcommons.wpi.edu/etd-dissertations/431.
Full textAbstract:
"In situ polymerizing hydrogel systems play an important role in many tissue engineering applications. They have proven to be useful in biomedical applications that require conversion of liquid macromer solution to tissue compliant hydrogel under physiological conditions. A series of poly(ethylene glycol)-co-poly(lactate) diacrylate macromers were synthesized with variable PEG molecular weight and lactate content. The macromer compositions were confirmed by NMR spectroscopy and ion chromatography. These macromers were polymerized to form hydrogels by free radical polymerization using either redox or photochemical initiators. The current study focused on the optimization of polymerization conditions. Compressive modulus and residual acrylate analysis were used to evaluate polymerization efficiency. To characterize the network structure, the swelling ratio values were converted to the average molecular weight between crosslinks ( ) and mesh sizes (ξ) using Flory-Rehner theory. Current study suggested hydrophobic modification is desired to achieve high polymerization efficiency. Electrospinning is a developing technique to produce ultra fine fibrous structures from polymer solutions. Current research efforts have focused on understanding the effects of principal parameters such as molecular weight distribution (MWD) and polymer surfactant interactions on the morphology of the electrospun patterns. Fundamental understanding of the dilute solution rheology of the polydisperse polymer/solvent and polymer/solvent/surfactant systems was first established. Using viscometry, the on-set of entanglement concentrations could be obtained for various systems. Electrospinning was then carried out to evaluate the effects of polymer molecular weight, molecular weight distribution (MWD) and the polymer-surfactant interaction on the fiber formation and morphological features. The importance of increased chain entanglements due to high molecular weight component within the polydisperse system and the expansion of the coil dimension by binding the surfactant micelles have been recognized. The critical concentrations for incipient as well as stable fiber formation were determined. "
38
Kim, Youngmi Ph D. "Synthesis and applications of electron deficient conjugated polymers." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32484.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2005.Vita.
Includes bibliographical references.
Chapter 1. In this introductory chapter, we present the general properties of conjugated polymers for sensory and electronic applications, with a special emphasis placed on electron-deficient materials. Chapter 2. In this chapter is presented the synthesis, characterization, and applications of a series of electron-deficient poly(p-phenylene vinylene)s (PPVs) homopolymers and copolymers. Poly(p-phenylenevinylene)s containing trifluoromethyl substituted aromatic rings (CF3- PPVs) exhibited high photooxidative stability to give robust materials suitable for molecular electronic device applications. Chapter 3. Hyperconjugative and Inductive Perturbations in Poly(p-phenylene vinylenes) New approaches that produce high fluorescence quantum yields and also tune electron affinity of conjugated polymers are presented. Novel three-dimensional poly(phenylene vinylenes) having [2.2.2] bicyclic ring system were synthesized to give highly efficient solid- state fluorescence and hyperconjugative and inductive electronic perturbations. The ability of hyperconjugative and inductive perturbation to tune the polymers' sensory applications was determined by investigating the fluorescence quenching responses to electron-rich and electron-deficient analytes in solution and solid thin films. Chapter 4. High Ionization Potential Conjugated Polymers In this chapter is presented a series of poly(p-phenylene ethynylenes) (PPEs) with high ionization potentials. Their photophysical properties were investigated using steady-state and time-resolved fluorescence techniques.
(cont.) The ionization potentials of the polymer thin films were determined using ultraviolet photoelectron spectroscopy (UPS), and those with the highest ionization potentials displayed high sensitivity for the detection of electron-donating aromatic compounds. The effects of sterics and electronic properties on the polymers' sensory responses were investigated by fluorescence quenching experiments in both solution and solid thin films. In addition, in some cases the excited state charge-transfer complexes (exciplexes) of the PPEs with analytes were observed. These effects provide promising opportunities for the formation of sensitive and selective chemical sensors. Chapter 5. Highly Emissive Conjugated Polymer Excimers Conjugated polymers often display a decrease of fluorescence efficiency upon aggregation due in large part to enhanced interpolymer interactions that produce weakly emissive species generally described as having excimer character. We have found that poly(phenylene ethynylene)s with fused pendant [2.2.2] ring structures having alkene bridges substituted with two ester groups function to give highly emissive, broad, and red-shifted emission spectra in the solid state. To best understand the origin of this new solid-state emissive species, we have performed photophysical studies of a series of different materials in solution, spin-coated thin films, solid solutions, and Langmuir films. We conclude that the new, red-shifted, emissive species originate from excimers produced by interchain interactions being mediated by the particular [2.2.2] ring system employed.
(cont.) The ability to predictably produce highly emissive excimers from conjugated polymers is important for the understanding how solid-state structures can control emissive behaviors. Chapter 6. Electron-Deficient Polyelectrolytes For Biosensory Applications In this chapter is described a novel photo-oxidizing water-soluble fluorescent polymer that was designed for the detection of electron-rich biological analytes. The polymer fluorescence is strongly quenched through an efficient photoinduced electron transfer from electron-donating aromatic moieties in amino acids, neurotransmitters, and proteins to the photo-oxidizing polymer. These efficient fluorescence quenching responses may be further enhanced by rapid exciton migration in the polymer backbone and further facilitated by ion- pairing between the polymer and quencher.
by Youngmi Kim.
Ph.D.
39
Ruano, Torres Guillem. "Conducting polymers and hybrid materials for technological applications." Doctoral thesis, Universitat Politècnica de Catalunya, 2021. http://hdl.handle.net/10803/673194.
Full textAbstract:
Depletion of natural resources and non-renewable energy sources has recently accelerated due to the development of globalized economy and industrialization. During the last years, the scientific community has devoted much of its efforts to developing and improving renewable energy sources. In this context, electrochemical capacitors, or supercapacitors, have received great interest owing to their properties and potential applications. Supercapacitors and their different components constitute the main line of work of the present thesis. More specifically the thesis investigates the use of hydrogels in various distinct functions. The work done in the thesis has been developed both experimentally and corroborated by theoretical studies based on quantum mechanics and molecular dynamics.
The main body of the thesis is divided into three parts. The first one includes the synthesis and characterization of a hydrogel derived from an unsaturated polyesteramide as a solid electrolyte in a supercapacitor. This part consists of the electrochemical characterization of the hydrogel obtained, evaluating the performance of the hydrogel when acting as a solid electrolyte, as well as a study of ion diffusion through the hydrogel carried out with molecular dynamics. These studies allow to obtain the optimal conditions for the synthesis and use of this hydrogel.
The second part is based on the preparation and characterization of a multilayer system as an electrode in a supercapacitor. More specifically, it covers the preparation of a multilayer system consisting of PVA and the conductive polymer PEDOT, prepared by a layer-by-layer process. The chapter also consists of a theoretical study of quantum mechanics in which the movement and changes of a PEDOT monolayer are studied, and allows to elucidate the mechanisms and electronic properties that had not been fully understood at the experimental level.
Finally, the third and last part incorporates the preparation of a multifunctional system consisting entirely of hydrogels. The chapter begins by detailing the preparation of an electrode of a supercapacitor based on a PEDOT hydrogel and alginate. After its characterization as an electrode, other functionalities that can be given to this system are explored. Among them, a reusable and recyclable pressure sensor is prepared to detect pressure changes linearly and with great sensitivity, as well as a controlled drug release system, in particular a controlled release by electrical stimulation of curcumin.Degut al desenvolupament de l'economia globalitzada i la industrialització, s'ha accelerat l'esgotament de recursos naturals i fonts d'energia no renovables. En els últims anys, la comunitat científica ha dedicat una gran part dels seus esforços a desenvolupar i millorar les fonts d'energia renovable. En aquest context, els capacitors electroquímics, o supercapacitors, han rebut un gran interès degut a les seves propietats i potencials aplicacions. El principal camp de treball d'aquesta tesis són els supercapacitors i les diferents parts que els constitueixen, més concretament la tesis estudia l'ús d'hidrogels en diverses funcions diferents. El treball fet a la tesis s'ha desenvolupat tant a nivell experimental com corroborat mitjançant estudis teòrics basats en la mecànica quàntica i la dinàmica molecular. El cos principal de la tesis està dividit en 3 parts. La primera part inclou la síntesis i caracterització d'un hidrogel derivat d'una poliesteramida insaturada com a electròlit sòlid en un supercapacitor. Aquesta part consta de la caracterització electroquímica de l'hidrogel obtingut, avaluant el rendiment de l'hidrogel a l'hora d'actuar com un electròlic sòlid, així com també consta d'un estudi de difusió dels ions a través d¿aquest dut a terme amb dinàmica molecular. Aquests estudis permeten obtenir les condicions òptimes per la síntesis i ús d'aquest hidrogel. La segona part està dedicada a la preparació i caracterització d'un sistema multicapa com a elèctrode en un supercapacitor. Més concretament, es basa en la preparació d'un sistema multicapa format per PVA i el polímer conductor PEDOT, preparat mitjançant un procés capa per capa. El capítol consta també d'un estudi teòric de mecànica quàntica en el que s'estudia el moviment i canvis d'una monocapa de PEDOT, i permet elucidar els mecanismes i propietats electròniques que no s'havien entès completament a nivell experimental. Finalment, l'última part es tracta de la preparació d'un sistema multifuncional format completament per hidrogels. El capítol comença detallant la preparació d'un elèctrode d'un supercapacitor basat en un hidrogel de PEDOT i alginat. Després de la seva caracterització com a elèctrode, s'exploren les altres funcionalitats que se li poden donar a aquest sistema. Es prepara un sensor de pressió reutilitzable i reciclable que permet detectar canvis de pressió linealment i amb una gran sensibilitat, i també es prepara un sistema d'alliberament controlat de fàrmacs, concretament l'alliberament controlat mitjançant estímul elèctric de curcumina
Polimers i biopolimers
40
James, Hodari-Sadiki L. "Thermo-Responsive Polymers for Cell-Based Therapeutic Applications." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1416231680.
Full text
41
Liu, Qingsheng. "Developing Ultralow-Fouling Multifunctional Polymers for Biomedical Applications." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1439840291.
Full text
42
Eccleston, Mark Edward. "Functional polymers for biomedical application : synthesis and applications." Thesis, Aston University, 1995. http://publications.aston.ac.uk/9591/.
Full textAbstract:
Aromatic and aliphatic diacid chlorides were used to condense naturally occurring diamino acids and their esterified derivatives. It was anticipated the resulting functional polyamides would biodegrade to physiologically acceptable compounds and show pH dependant solubility could be used for biomedical applications ranging from enteric coatings to hydrosoluble drug delivery vehicles capable of targeting areas of low physiological pH. With these applications in mind the polymers were characterised by infra red spectroscopy, gel permeation chromatography and in the case of aqueous soluble polymers by potentiometric titration. Thin films of poly (lysine ethyl ester isophthalamide) plasticised with poly (caprolactone) were cast from DMSO/chloroform solutions and their mechanical properties measured on a Hounsfield Hti tensiometer. Interfacial synthesis was investigated as a synthetic route for the production of linear functional polyamides. High molecular weight polymer was obtained only when esterified diamino acids were condensed with aromatic diacid chlorides. The method was unsuitable for the production of copolymers of free and esterified amino acids with a diacid chloride. A novel miscible mixed solvent single phase reaction was investigated for production of copolymers of esterified and non-esterified amino acids with diacid chlorides. Aliphatic diacid chlorides were unsuitable for condensing diamino acids using this technique because of high rates of hydrolysis. The technique gave high molecular weight homopolymers from esterified diamino acids and aromatic diacid chlorides.
43
Yassin, Zakiya. "Characterization of OSTE-based polymers for acoustofluidic applications." Thesis, KTH, Tillämpad fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209924.
Full text
44
Haynes, Dahlia. "Novel lactide derived polymers ; syntheses, properties and applications." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1239896057/.
Full text
45
Miyata, Mamoru. "Synthesis of novel organoboron polymers and their applications." 京都大学 (Kyoto University), 2003. http://hdl.handle.net/2433/148876.
Full text
46
ERRAHALI, MINA. "Microporous polyaromatic polymers designed for gas storage applications." Doctoral thesis, Università del Piemonte Orientale, 2015. http://hdl.handle.net/11579/115581.
Full text
47
INVERARDI, NICOLETTA. "3D Printed Shape Memory Polymers for Biomedical Applications." Doctoral thesis, Università degli studi di Brescia, 2021. http://hdl.handle.net/11379/544096.
Full text
48
Cheung, Wai-kei, and 張偉基. "Low band-gap donor-acceptor polymers and heterolyptic ruthenium complex containing polymers for photovoltaic applications." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B47753006.
Full textAbstract:
A series of low band-gap conjugated polymers with intramolecular charge
transfer properties were synthesized and bulk heterojunction devices based on
these polymers were fabricated. The electrochemical and photophysical properties
of the polymers were tuned by using different electron withdrawing molecules or
ruthenium complexes as the comonomer. Preliminary results suggested that the
electronic structures of the polymer were significantly altered by the incorporation
of different acceptor units. The polymers also demonstrated intense absorption
bands in the visible region, indicating that they are suitable photoactive materials
in bulk heterojunction devices.
The synthesis and characterization of a series of organic donor-acceptor
copolymers were studied. All of the polymers contained alternating
cyclopenta[2,1- b:3,4-b’]dithiophene (CPDT) units. The effects of the different
acceptor monomers were evaluated. The electron-withdrawing carboxylate and
amide functional groups of the acceptors were found to effectively stabilize the
HOMO levels of the polymer, and the optical band-gaps were significantly
reduced. Bulk heterojunction devices were fabricated using the polymers and
6,6-phenyl C61 butyric acid methyl ester (PCBM) as donors and acceptors
respectively. These devices exhibited high open circuit voltage (Voc) up to 0.86 V.
The extended photosensitizing range was confirmed by the external quantum
efficiency (EQE) spectra. The device performance was further improved by
optimizing the active layer thickness and applying 1,8-diiodooctane in the blend
solution.
A new synthetic route to novel ruthenium containing polymers was also
reported. [Ru(L)(L’)Cl2] complexes (L and L’ = bidentate N^N ligands) with a
dibromo-substituted ligand were found to be polymerizable by Stille cross-coupling
reaction. The subsequent displacement of the chloride ligands by
thiocyanate was highly effective and the structures of the target polymers were
fully characterized. The main chain absorption showed a significant red-shift upon
metal coordination and the metal-to-ligand charge transfer (MLCT) of the
complex strengthens the photon harvesting ability of the polymer. The dual
function of these Ru(II) complexes demonstrated a new avenue to develop new
classes of optoelectronic materials. The extent of _-delocalization of the ancillary
ligands also showed interesting effects on the electronic properties of the
polymers. Bulk heterojunction devices were fabricated. Photovoltaic response was
observed in these devices, and the device performance can be improved by further
modifying the surface morphology of the blend films.published_or_final_version
Chemistry
Master
Master of Philosophy
49
Hughes-Brittain, Nanayaa Freda. "Photoembossing for biomedical applications." Thesis, Queen Mary, University of London, 2014. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8294.
Full textAbstract:
Surface topography is known to be important in biomedical applications such as scaffolds for tissue regeneration and has been shown to affect wettability and cell behaviour. Traditionally, topographical effects such as surface texturing have been generated using methods such as photolithography, soft lithography, thermal embossing, and laser/electron beam techniques. This thesis introduces a relatively new technique known as photoembossing to create surface texturing for biomedical applications. Photoembossing is used to produce surface texturing on polymer surfaces by patterned ultraviolet (UV) exposure of a photopolymer blend without an etching step or an expensive mould. After a short general introduction and a literature review, the first experimental chapters describe surface patterning of poly(methyl methacrylate) (PMMA) photopolymer substrates by photoembossing. PMMA is blended with an acrylate monomer and photoinitiator by dissolution in a volatile solvent and processed into films by wire bar coating, and fibres are produced by electrospinning. Surface texture is achieved on both films and fibres by photoembossing. Endothelial cell culture shows that the substrates are biocompatible and cells readily adhere to the surface. In tissue regeneration applications, scaffold degradation is often important to allow tissue in-growth. Thus, in subsequent studies polylactide-co-glycolide (PLGA) is used as a polymer binder. PLGA blended with a triacrylate monomer showed partial degradation after 10 weeks, with a cross-linked acrylate network remaining. Endothelial cell adhesion was even better on the PLGA photopolymer substrates compared to PMMA. Furthermore, surface texture improved cell adhesion and proliferation on the PLGA photopolymer. To obtain completely degradable substrates, thiol monomer was used in addition to the acrylate to produce ester bonds after the thiol-ene reaction, which is cleavable by hydrolysis. Accelerated degradation in sodium hydroxide (NaOH) showed complete degradation of this photopolymer system. The degradation rate of the photopolymer could be tuned by the molecular weight of the acrylate monomer, with low molecular weight monomers degrading more slowly than high molecular weight species. Furthermore, the height of the surface relief structures could be enhanced by using low-molecular-weight acrylate monomers. Endothelial cell culture revealed biocompatibility of the blend and cells were able to adhere after 24 hours of seeding. This thesis demonstrates that photoembossing is a viable technique in producing surface texture for tissue engineering applications. This surface texture can be achieved on both biocompatible and biodegradable photopolymer films and fibres.
50
Mellinger, Axel. "Charge storage in electret polymers mechanisms, characterization and applications /." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=976642212.
Full text