Dissertations / Theses on the topic 'Electro-active polymers'

Background : Heart failure is one of the principal causes of death and disability. The causes of heart failure are many, and a number of technologies have been developed to address this issue by providing support to the failing heart, both as a permanent solution and as a bridge to recovery. These options are called Mechanical Circulatory Support Devices, a particular branch of these devices is the Ventricular Assist Devices, which have been under intense development over the recent years offering a promising solution for this major problem. However, these devices are still bulky, and heavy designed to support failing hearts in the adult population. On the other hand, little has been done in recent times on the development of implantable solutions for heart failure or insufficiency in children. There are many reasons for this, but primarily the relatively small number of children requiring these procedures, the challenges associated with growth, and the lack of physical space for such implantable circulatory support technologies in children are fundamental limitations to the development and deployment of these technologies. Aims of the project : The primary purpose of this project was to investigate the development of a new miniaturised self-power VAD that is suitable for paediatrics implantation. This project suggested the use of the newly developed Artificial Muscles to create a mesh that envelops the heart and works as an external assisting circulation mechanism. The same materials could be used to generate electricity when deformed, which can be used to power the proposed device. Critically, the project was to focus on optimising the materials with regard to their operating efficiency to ascertain whether they represent a viable option for VAD production. Materials and Methods : A full review of the current available Artificial Muscles was performed to choose the most suitable type for this project. Then different fabrication protocols were developed to make IPMC Artificial Muscles using platinum and palladium coatings. A series of characterization tests were conducted on the fabricated Ionic Polymeric Metal Composites (IPMC) to ensure their quality. Finally, the mechanical and electrical properties were tested and compared with the proposed device requirements. Results : The review of Artificial Muscles showed that IPMC would be the best candidate to use in this application. The characterisation tests showed as well that the produced IPMC Artificial Muscles were fabricated to the same standards as those commercially available, and the reported by other investigators. However, these materials showed very low mechanical output with high electrical power consumption, which made them far from practical and not suitable for the proposed application. On the other hand, IPMCs showed promising results as an option to generate electricity to power low consumption implantable devices.

The aim of the present work was to screen the main methods for the synthesis of conjugated polymers for their suitability in the preparation of conductive polymer brushes. The main focus was put on the grafting of intrinsically soluble substituted regioregular polyalkylthiophenes because of their excellent optoelectronic properties. The resulting polymer films were characterized and their optoelectrical properties studied. For the first time, a synthesis of conductive polymer brushes on solid substrates using “grafting-from” method was performed. The most important, from my opinion, finding of this work is that regioregular head-to-tail poly-3-alkylthiophenes – benchmark materials for organic electronics - can be now selectively grafted from appropriately-terminated surfaces to produce polymer brushes of otherwise soluble polymers - the architecture earlier accessible only in the case of non-conductive polymers. In particular, we developed a new method to grow P3ATs via Kumada Catalyst Transfer Polymerization (KCTP) of 2-bromo-5-chloromagnesio-3-alkylthiophene. Exposure of the initiator layers to monomer solutions leads to selective chain-growth polycondensation of the monomers from the surface, resulting into P3AT brushes in a very economical way. The grafting process was investigated in detail and the structure of the resulting composite films was elucidated using several methods. The obtained data suggests that the grafting process occurs not only at the poly(4-bromstyrene) (PS-Br)/polymerization solution interface, but also deeply inside the swollen PS-Br films, penetrable for the catalyst and for the monomer The grafting process was investigated in detail and the structure of the resulting composite film was elucidated using ellipsometry, X-ray Photoelectron Spectroscopy (XPS), Rutherford backscattering spectroscopy (RBS), and Conductive atomic force microscopy (C-AFM). The obtained data suggests that the grafting process occurs not only at the poly(4-bromostyrene), PS-Br/polymerization solution interface, but also deeply inside the swollen PS-Br film, which is penetrable for the catalyst and the monomer. The process results in an interpenetrated PS-Br/P3HT network, in which relatively short poly(3-hexylthiophene), P3HT grafts emanate from long, cross-linked PS-Br chains. A further method investigated during our work was to covalently graft regioirregular P3HT to substrates modified by macromolecular anchors using oxidative polymerization of 3HT with FeCl3. P3HT layers with variable thicknesses from 30 nm up to 200 nm were produced using two steps of polymerization reaction. The P3HT obtained by oxidative polymerization had always an irregular structure, which was a result of the starting monomer being asymmetric, which is undesired for electronic applications. The third method for the production of conductive polymer brushes was to graft regioregular poly(3,3''-dioctyl-[2,2';5',2'']terthiophene) (PDOTT) by electrochemical oxidative polycondensation of symmetrically substituted 3,3''-dioctyl-[2,2';5',2'']terthiophene (DOTT). A modification of the supporting ITO electrode by the self-assembled monolayers (SAMs) of compounds having polymerizable head-groups with properly adjusted oxidative potentials was found to be essential to achieve a covalent attachment of PDOTT chains. The polymer films produced show solvatochromism and electrochromism, as well as the previous two methods. After polymerization, the next step towards building organic electronic devices is applying the methods obtained in nano- and microscale production. Block copolymers constitute an attractive option for such surface-engineering, due to their ability to form a variety of nanoscale ordered phase-separated structures. However, block copolymers containing conjugated blocks are less abundant compared to their non-conjugated counterparts. Additionally, their phase behaviour at surfaces is not always predictable. We demonstrated in this work, how surface structures of non-conductive block copolymers, such as P4VP-b-PS-I, can be converted into (semi)conductive P4VP-b-PS-graft-P3HT chains via a surface-initiated polymerization of P3HT (Kumada Catalyst Transfer Polymerization (KCTP) from reactive surface-grafted block copolymers. This proves that our method is applicable to develop structured brushes of conductive polymers. We believe that it can be further exploited for novel, stimuli-responsive materials, for the construction of sensors, or for building various opto-electronic devices. The methods developed here can in principle be adapted for the preparation of any conductive block copolymers and conductive polymers, including other interesting architectures of conductive polymers, such as block copolymers, cylindrical brushes, star-like polymers, etc. To this end, one needs to synthesize properly-designed and multi-functional Ni-initiators before performing the polycondensation.

The aim of the present work was to screen the main methods for the synthesis of conjugated polymers for their suitability in the preparation of conductive polymer brushes. The main focus was put on the grafting of intrinsically soluble substituted regioregular polyalkylthiophenes because of their excellent optoelectronic properties. The resulting polymer films were characterized and their optoelectrical properties studied. For the first time, a synthesis of conductive polymer brushes on solid substrates using “grafting-from” method was performed. The most important, from my opinion, finding of this work is that regioregular head-to-tail poly-3-alkylthiophenes – benchmark materials for organic electronics - can be now selectively grafted from appropriately-terminated surfaces to produce polymer brushes of otherwise soluble polymers - the architecture earlier accessible only in the case of non-conductive polymers. In particular, we developed a new method to grow P3ATs via Kumada Catalyst Transfer Polymerization (KCTP) of 2-bromo-5-chloromagnesio-3-alkylthiophene. Exposure of the initiator layers to monomer solutions leads to selective chain-growth polycondensation of the monomers from the surface, resulting into P3AT brushes in a very economical way. The grafting process was investigated in detail and the structure of the resulting composite films was elucidated using several methods. The obtained data suggests that the grafting process occurs not only at the poly(4-bromstyrene) (PS-Br)/polymerization solution interface, but also deeply inside the swollen PS-Br films, penetrable for the catalyst and for the monomer The grafting process was investigated in detail and the structure of the resulting composite film was elucidated using ellipsometry, X-ray Photoelectron Spectroscopy (XPS), Rutherford backscattering spectroscopy (RBS), and Conductive atomic force microscopy (C-AFM). The obtained data suggests that the grafting process occurs not only at the poly(4-bromostyrene), PS-Br/polymerization solution interface, but also deeply inside the swollen PS-Br film, which is penetrable for the catalyst and the monomer. The process results in an interpenetrated PS-Br/P3HT network, in which relatively short poly(3-hexylthiophene), P3HT grafts emanate from long, cross-linked PS-Br chains. A further method investigated during our work was to covalently graft regioirregular P3HT to substrates modified by macromolecular anchors using oxidative polymerization of 3HT with FeCl3. P3HT layers with variable thicknesses from 30 nm up to 200 nm were produced using two steps of polymerization reaction. The P3HT obtained by oxidative polymerization had always an irregular structure, which was a result of the starting monomer being asymmetric, which is undesired for electronic applications. The third method for the production of conductive polymer brushes was to graft regioregular poly(3,3''-dioctyl-[2,2';5',2'']terthiophene) (PDOTT) by electrochemical oxidative polycondensation of symmetrically substituted 3,3''-dioctyl-[2,2';5',2'']terthiophene (DOTT). A modification of the supporting ITO electrode by the self-assembled monolayers (SAMs) of compounds having polymerizable head-groups with properly adjusted oxidative potentials was found to be essential to achieve a covalent attachment of PDOTT chains. The polymer films produced show solvatochromism and electrochromism, as well as the previous two methods. After polymerization, the next step towards building organic electronic devices is applying the methods obtained in nano- and microscale production. Block copolymers constitute an attractive option for such surface-engineering, due to their ability to form a variety of nanoscale ordered phase-separated structures. However, block copolymers containing conjugated blocks are less abundant compared to their non-conjugated counterparts. Additionally, their phase behaviour at surfaces is not always predictable. We demonstrated in this work, how surface structures of non-conductive block copolymers, such as P4VP-b-PS-I, can be converted into (semi)conductive P4VP-b-PS-graft-P3HT chains via a surface-initiated polymerization of P3HT (Kumada Catalyst Transfer Polymerization (KCTP) from reactive surface-grafted block copolymers. This proves that our method is applicable to develop structured brushes of conductive polymers. We believe that it can be further exploited for novel, stimuli-responsive materials, for the construction of sensors, or for building various opto-electronic devices. The methods developed here can in principle be adapted for the preparation of any conductive block copolymers and conductive polymers, including other interesting architectures of conductive polymers, such as block copolymers, cylindrical brushes, star-like polymers, etc. To this end, one needs to synthesize properly-designed and multi-functional Ni-initiators before performing the polycondensation.

Le concept de la récupération d'énergie se rapporte généralement au processus d'utilisation de l'énergie ambiante, qui est converti, principalement (mais pas exclusivement) en énergie électrique pour faire fonctionner des dispositifs électroniques petites et autonomes. Les tendances récentes à la fois dans l'industrie et au domaine de la recherche ont mis l'accent sur les polymères électro-actifs pour la conversion d'énergie électromécanique. Cet intérêt s'explique par de nombreux avantages tels que la productivité élevée, la grande flexibilité, et la facilité de traitement. Le but de ce travail de recherche est d’explorer la potentialité des polymères électro-actifs pour une application de récupération d’énergie mécanique ambiante. Dans la première partie, une synthèse des composites à base de polyuréthane (PU) et de P(VDF-TrFE-CFE) a été réalisée, suivie d’une caractérisation électrique et mécanique de ces polymères et composites afin d’évaluer leurs paramètres intrinsèques. La seconde partie de ce travail de thèse concerne la caractérisation électromécanique de ces polymères. Un modèle analytique électromécanique est mise en place afin de déterminer finement le comportement physique des polymères électrostrictifs ainsi que les variations de leurs paramètres intrinsèques. Ce modèle analytique est validé par une série de tests à travers un banc d’essai. La dernière partie de ce travail consiste à évaluer les performances électromécaniques des polymères électrostrictifs pour la récupération d’énergie mécanique. Deux nouvelles techniques sont testées afin de maximiser la densité d’énergie récupérée. Ainsi qu’une comparaison avec les méthodes classiques a été réalisée. Un excellent potentiel de ces techniques pour la récupération d'énergie a été démontré. Le deuxième point porte sur l’étude de l’efficacité de la conversion électromécanique pour la récupération d’énergie mécanique en utilisant l'analyse spectrale FFT. Il a été montré que cette méthode permet de prévoir le rendement énergétique de nos polymères en accord avec les prédictions théoriques. Le dernier point se focalise sur l’amélioration de cette efficacité de conversion électromécanique en utilisant des électrets de polypropylène cellulaire, afin d’assurer un meilleur rendement énergétique
The concept of energy harvesting generally relates to the process of using ambient energy, which is converted, primarily (but not exclusively) into electrical energy in order to power small and autonomous electronic devices. Recent trends in both industrial and research fields have focused on electro-active polymers for electromechanical energy conversion. This interest is explained by many advantages such as high productivity, high flexibility, and processability. The purpose of this research work is to explore the potential of electro-active polymers for application of mechanical energy harvesting. At first, a synthesis of the composite based on polyurethane (PU) and P (VDF-TrFE-CFE) was performed, followed by electrical and mechanical characterization of these polymers and composites in order to evaluate their intrinsic parameters. The second part of this thesis concerns electromechanical characterization of these polymers. An electromechanical analytic modeling is detailed in order to determine the physical behavior of electrostrictive polymers and the variations of intrinsic parameters. This modeling is validated by a series of tests using a test bench. The last part of this work consists to evaluate the electromechanical performance of electrostrictive polymers for the mechanical energy harvesting. Two new techniques are tested in order to maximize the density of energy recovered. As well as a comparison against those classic has been performed. Excellent potential of these techniques for energy harvesting has been demonstrated. The second point is about the study of the electromechanical conversion efficiency for scavenging mechanical energy using spectral analysis FFT. It was shown that this method allows predicting the energy efficiency of our polymers, in accordance with the results predicted by the model. The last point focuses on improving the efficiency of electromechanical conversion by using cellular polypropylene electrets to ensure better energy efficiency

Additive manufacturing has grown considerably during the last couple of decades, whether it comes to the printing of metal structure or living cells. Additive manufacturing techniques relays on the successive addition of material to create the wanted structure. Among the diversity of these many printing techniques, electrohydrodynamic 3D-printing is of particular interest, as the technique has a promising outlook for high-resolution printing on the microscale. The technique is compatible with a myriad of thermoplastics, but its writing resolution is limited due to the inherent affect the manufacturing process has on the material. Electrostatic forces between already deposited fibres and the fibre in light affect the final position of printed fibre. This thesis evaluates the possibility to increase the writing resolution in melt electrohydrodynamic 3D printing by a closed-loop feedback system. Components were built and added to an already existing printing setup to implement in-situ measurements of the fibres position as well as active electrostatic guiding of the fibre. The setup consisted of a camera that determined the position of the fibre; the position was then used in a PID controller to calculate an appropriate potential. The potential was forwarded to a high voltage amplifier, connected to a steering electrode, mounted in the vicinity of the jet. The setup built for one-dimensional steering of the fibre improved the printing accuracy by ten times through suppressing the repulsive/attractive forces, where the process variable of the PID controller was measured. However, the precision decreased roughly four times as it was deposited on the substrate. The limitations of the system have been evaluated, and possible improvements for the two-dimensional control of the fibre are further discussed.

Electrically conductive or electro-active fibers are the key components of smart and interactive textiles, which could be used in medical, sports, energy, and military applications in the near future. The functionalization of high-performance textile yarns/fibers with conjugated polymers can produce conductive fibers with better electro-mechanical properties, which is difficult with commonly used spinning techniques. In this thesis work, textile-based conductive yarns/fibers were prepared by coating viscose and polyester (PET) yarns with the conjugated polymer PEDOT. For coating purposes, an efficient technique called chemical vapor deposition (CVD) was used, which is a solventless technique and can produce PEDOT polymer layers with high conductivity values. The polymerization of EDOT monomer vapors and coating of oxidant (FeCl3 or FepTS) enriched viscose and PET yarns took place simultaneously. The PEDOT-coated viscose and polyester yarns showed relatively high conductivity values, which could be sufficient for many electronic applications. The polymerization process and the quality of PEDOT polymer strongly depends on different reaction conditions. In this research work, the impact of most of these reaction parameters on the electrical, mechanical, and thermal properties of PEDOT-coated conductive yarns was considered separately. Under specific reaction conditions, it was found that viscose fibers were successfully coated with PEDOT polymer and showed rather high electrical conductivity (≥ 15 S/cm). However, due to the acid hydrolysis of viscose fibers in FeCl3 solutions, the mechanical properties were drastically reduced. In order to improve the mechanical properties of conductive yarns, a relatively stable and chemical-resistant substrate (PET) was coated with PEDOT polymer. Comparative studies between PEDOT-coated viscose and PET conductive yarns showed that the electrical and mechanical properties were enhanced by changing the substrate material. Later on, PEDOT-coated conductive fibers were treated with silicone elastomer solution and due to the thin silicone layers, the hydrophobic properties, flexibility, and durability of coated yarns was improved. Furthermore, a novel electrical resistance-measuring setup was developed, which can be used not only for fibers but also for fabric structures. The electrical characterization of PEDOT-coated conductive yarns showed that it can be used effectively for sensitive fibers without damaging their surface morphology. Finally, the use of conductive yarns as stretch sensors was evaluated. For this purpose, small rectangular knitted patches of conductive yarns were prepared and then the change in electrical resistance values at different extension percentages (5–50%) was investigated. The constant variations in electrical resistance values at different extension and relaxation cycles for longer periods of time revealed that the conductive yarns produced have the potential to be used as stretch sensors for monitoring of vital signs in medical and sports applications.

Thesis for the Degree of Doctor of Philosophy to be presented on March 08, 2013, 10.00 in KA-salen, Kemigården 4, Chalmers University of Technology, Gothenburg

[EN] The use of latent heat storage materials containing phase change materials (PCM's) is an effective way of buffering thermal fluctuations and has the advantages of high-energy storage density and the isothermal nature of the storage process. The aim of this work was to develop novel heat management materials based on the encapsulation of PCM's for different applications of interest in refrigerated foods. To this end, the electro-hydrodynamic processing was used to encapsulate commercial PCM's with transition temperatures of interest in refrigeration and superchilling within different polymer and biopolymer matrices. Initially, materials with heat management capacity to be used in refrigeration equipment and packaging applications were designed. To this end, thick slabs, multilayer heat storage structures and polystyrene foam trays containing ultrathin fiber-structured polystyrene/PCM coatings were fabricated through the encapsulation of commercial phase change materials (specifically paraffin's) within different polymeric matrices. The morphology, thermal properties, encapsulation efficiency and temperature profile of the just prepared structures and after three months of storage at 4 and 25ºC were evaluated. However, the developed electrospun heat management materials showed a multiple crystallization profile, increased supercooling degree (difference between the melting and crystallization temperatures), low encapsulation efficiency and partial diffusion out of the PCM from the electrospun structures during ageing. Therefore, different strategies were been carried out to counteract these drawbacks. One the one hand, thermal energy storage systems including a PCM which crystallize at -1.5ºC were optimized by adjusting the solvent composition in order to obtain hybrid electrospun fibers with thermal properties similar to those of the neat PCM. On the other hand, a hydrophilic shell material based on polyvinylalcohol (PVOH) was used to encapsulate the PCM by using the emulsion electrospinning technique in order to improve the encapsulation efficiency. However, the hybrid structures thus prepared were highly soluble in water at high relative humidity conditions and an extra layer of a more hydrophobic material (polycaprolactone) through coaxial electrospinning was used to protect them from swelling. The use of the coaxial configuration was a good strategy to preserve the morphology of the electrospun structures when exposed to high relative humidity.
[ES] El uso de materiales de almacenamiento de calor latente que contienen materiales de cambio de fase (PCM's) es una manera eficiente de amortiguar las fluctuaciones de temperatura y presenta las ventajas de proveer alta densidad de almacenamiento de energía y la naturaleza isotérmica del proceso de almacenamiento. El objetivo de este trabajo fue desarrollar nuevos materiales con capacidad de gestión de calor mediante la encapsulación de PCM's para diferentes aplicaciones de interés en alimentos refrigerados. Para ello, se utilizó el procesado electrohidrodinámico para encapsular PCM's comerciales con temperaturas de transición de fase de interés en refrigeración y superenfriamiento dentro de matrices poliméricas y biopoliméricas. Inicialmente, se diseñaron materiales con capacidad de gestión de calor para ser utilizados en equipos de refrigeración y aplicaciones de envasado. Con este propósito, se fabricaron bloques, estructuras multicapa y bandejas de poliestireno que contenían un recubrimiento de fibras nanoestructuradas ultrafinas mediante la encapsulación de materiales de cambio de fase (especialmente parafinas) dentro de diferentes matrices poliméricas. Se evaluó la morfología, propiedades térmicas, eficiencia de encapsulación y perfil de temperatura de las estructuras recién preparadas y después de tres meses de almacenamiento a 4 y 25ºC. No obstante, se observó que los materiales electroestirados con capacidad de gestión de calor presentaron un perfil de cristalización múltiple, un incremento en el grado de subenfriamiento (diferencia entre las temperaturas de fusión y de cristalización), baja eficiencia de encapsulación y una difusión parcial del PCM de las estructuras electroestiradas durante el periodo de almacenamiento. Para contrarrestar estos efectos, se llevaron a cabo dos estrategias diferentes. Por un lado, se optimizaron los sistemas de almacenamiento de energía térmica incluyendo un PCM que cristaliza a -1.5ºC mediante el ajuste de la composición de los disolventes con el fin de obtener fibras hibridas electroestiradas con propiedades térmicas similares al PCM puro. Por otro lado, para mejorar la eficiencia de encapsulación se utilizó un material hidrófilo basado en polivinilalcohol (PVOH) como material de recubrimiento para encapsular el PCM usando la técnica de electroestirado a partir de una emulsión. Sin embargo, se observó que las estructuras hibridas preparadas fueron altamente solubles en agua y en condiciones de alta humedad relativa. Por tanto, para protegerlos se incorporó una capa adicional de un material más hidrofóbico (policaprolactona) mediante la técnica de electroestirado coaxial. El uso de la configuración coaxial fue la mejor estrategia para preservar la morfología de las estructuras electroestiradas cuando éstas fueron expuestas a condiciones de alta humedad relativa.
[CAT] L'ús de materials d'emmagatzematge de calor latent que contenen materials de canvi de fase (PCM) és una manera eficaç d'esmorteir les fluctuacions tèrmiques. A més a més presenta els avantatges de posseir una alta densitat d'emmagatzematge energia així com la naturalesa isotèrmica del procés d'emmagatzematge. L'objectiu d'aquest treball va ser desenvolupar productes amb capacitat de gestió de calor mitjançat l' encapsulació de PCM per a diferents aplicacions d'interès en la conservació d'aliments refrigerats. Amb aquesta finalitat, es va utilitzar el processament electro-hidrodinàmic per encapsular PCM comercials dins de diferents matrius polimériques i biopolimériques, amb temperatures de transició d'interès en el procés de conservació d'aliments refrigerats. Inicialment, es van dissenyar materials amb capacitat de gestió de calor per ser utilitzats en equips de refrigeració i en el envasat d'aliments refrigerats. Per a tal fi, es van dissenyar blocs, materials multicapa i safates de poliestirè que contenien un recobriment nanoestructurat i ultrafí amb encapsulats de materials de canvi de fase comercials (específicament parafines) dins de diverses matrius polimèriques. Es va caracteritzar la morfologia, les propietats tèrmiques, l'eficiència de encapsulació i la capacitat d'emmagatzematge d'energia just en el moment en el que es van preparar i després de tres mesos d'emmagatzematge a 4 y 25ºC. No obstant això, els materials desenvolupats van mostrar un perfil de cristal·lització múltiple, un augment del grau de subrefredament (diferència entre les temperatures de fusió i de cristal·lització), una baixa eficiència d'encapsulació i una difusió parcial del PCM de les estructures electroestirades durant el període d'emmagatzematge. Per tant, diferents estratègies han estat portades a terme per contrarestar aquests inconvenients. D'una banda, amb la finalitat d'obtenir fibres híbrides electroestirades amb propietats tèrmiques similars a les de la PCM pur, es van optimitzar els sistemes d'emmagatzematge d'energia tèrmica que incloïen un PCM que fon a -1,5 ºC variant la composició dels dissolvents. D'altra banda, es va utilitzar un material de la closca hidròfil basat en polivinílic alcohol (PVOH) per encapsular el PCM mitjançant l'ús de la tècnica d'electroestirat d'una emulsió per tal de millorar l'eficiència d'encapsulació. No obstant això, les estructures híbrides així preparades van ser altament soluble en aigua a altes condicions d'humitat relativa i va ser necessari utilitzar una capa addicional d'un material més hidròfob (policaprolactona) a través de la configuració coaxial de l'equip d'electroestirat. L'ús de la configuració coaxial va ser una bona estratègia per preservar la morfologia de les estructures electroestirades quan s'exposen a altes humitats relatives.
Chalco Sandoval, W. (2015). Development of Temperature Buffering Material Concepts Based on Electro-Hydrodynamic Processing of Interest in the Food Cold Chain [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/53349
TESIS

Les polymères électro-actifs (EAP) tels que le P (VDF-TrFE-CTFE) se sont révélés très prometteurs dans le domaine des capteurs et actionneurs flexibles. Les avantages de l'utilisation des PAE pour les appareils électriques intelligents sont dus à leur faible coût, leurs propriétés élastiques, leur faible densité et leur capacité à être fabriqués en différentes formes et épaisseurs. Au cours des années précédentes, le terpolymère P (VDF-TrFE-CTFE) a attiré de nombreux chercheurs en raison de sa propriété ferroélectrique relaxante qui présente des phénomènes d'électrostriction élevés. Malgré leur attractivité, cette classe de matériaux possède encore deux limitations technologiques principales: une faible tension de claquage et le niveau élevé de courant de fuite lorsque des tensions élevées sont appliquées. La dépendance quadratique de la réponse de déformation et de la densité d'énergie mécanique sur le champ électrique appliqué met en évidence la pertinence du champ électrique de claquage EAP, tout en réduisant les pertes diélectriques. La faible rigidité diélectrique du terpolymère P (VDF-TrFE-CTFE) s'avère être une préoccupation majeure pour obtenir des performances d'actionnement élevées. De plus, le grand champ électrique nécessaire pour atteindre des niveaux de déformation satisfaisants (≥ 40 V / µm, environ) conduit inévitablement à un niveau élevé de courant de fuite et donc à une durée de vie courte. Ce travail démontre qu'il est possible d'augmenter considérablement le claquage électrique et de diminuer les pertes diélectriques en contrôlant les paramètres de traitement des procédés de synthèse et de fabrication des polymères. L'amélioration de la rigidité diélectrique intrinsèque est obtenue en ajustant le poids moléculaire du terpolymère et en améliorant la pureté de la dissolution polymère utilisée pour la fabrication de films de terpolymère. La réduction des pertes diélectriques, et avec une attention particulière aux pertes de conduction à haute tension (ou courant de fuite), est obtenue par l'introduction d'un nouveau traitement thermique dans le processus de fabrication du film, appelé recuit électro-thermique
Electro-active polymers (EAPs) such as P(VDF-TrFE-CTFE) was demonstrated to be greatly promising in the field of flexible sensors and actuators. The advantages of using EAPs for smart electrical devices are due to their low cost, elastic properties, low density and ability to be manufactured into various shapes and thicknesses. In earlier years, P(VDF-TrFE-CTFE) terpolymer attracted many researchers due to its relaxor-ferroelectric property that exhibits high electrostriction phenomena. Although their attractiveness, this class of materials still owns two main technological limitations: low breakdown voltage and the high level of leakage current when high voltages are applied. The quadratic dependence of the strain response and mechanical energy density on the applied electric field highlights the relevance of EAP breakdown electric field, while reducing the dielectric losses. The low dielectric strength of P(VDF-TrFE-CTFE) terpolymer turns out to be a main concern for achieving high actuation performances. Moreover, the large of electric field required to attain satisfactory levels of deformation (≥ 40 V/µm, about) inevitably lead to high level of leakage current and thus short life-time. This work demonstrates that it is possible to dramatically increase the electrical breakdown and decrease the dielectric losses by controlling processing parameters of the polymer synthesis and fabrication procedures. Enhancement of intrinsic dielectric strength is obtained by tuning the terpolymer molecular weight and by improving the purity of polymeric dissolution used for fabrication of terpolymer films. The reduction of dielectric losses, and with particular attention at the high-voltage conduction losses (or leakage current) are achieved by the introduction of a novel thermal treatment in the film fabrication process, called electro-thermal annealing

Les travaux exposés dans cette thèse traitent de la modélisation multiphysique et de la commande distribuée de structures flexibles actionnées à l’aide de polymères électro-actifs de type Ionic Polymer Metal Composite (IPMC). Dans un premier temps, nous proposons une formulation Hamiltonnienne à ports de l’actionneur IPMC afin de tenir compte des couplages multiphysiques et multiéchelles. Des multiplicateurs de Lagrange sont utilisés pour gérer les contraintes mécaniques apparaissant au sein de l’actionneur. La structure mécanique de la structure flexible est quant à elle modélisée en 1D à l’aide de modèles de poutres et en 2D à l’aide d’un modèle de coques fines. Dans un second temps, deux méthodes de discrétisation préservant la structure sont présentées et étendues aux systèmes Hamiltoniens à ports de dimension infinie avec dissipation et entrée distribuée. Le modèle de l’actionneur est validé expérimentalement à l’aide d’une discrétisation de type différences finies sur grilles en quinconces. Dans un troisième temps, nous développons sur un modèle simplifié de type corde vibrante, une loi de commande distribuée dans le domaine à l’aide de patches, permettant de modeler la fonction d’énergie globale du système et d’injecter de la dissipation
This thesis deals with the multiphysical modeling and the distributed control of flexible structures actuated by Ionic Polymer Metal Composite (IPMC) actuators. We firstly propose a model for the IPMC actuator using infinite dimensional port-Hamiltonian formulations in order to tackle the multiphysical and multiscale couplings. Lagrange multipliers are used to handle the mechanical constraints appearing in the actuator. The mechanical structure of the flexible structure is then modeled in 1D with beam models and in 2D with a thin shell model. Secondly, two structure preserving discretization methods are presented and extended to infinite dimensional dissipative port-Hamiltonian system with distributed input. The proposed IPMC actuator model is then discretized using the structure preserving finite differences method on staggered grids and validated on experimental data. Thirdly, we propose an in-domain distributed control law on a simplified model i.e. the vibrating string actuated with patches, that allows to shape the total energy of the system and to inject damping in order to stabilize the overall system with predefined performances

A special actuator device with passive sensing capability based on dielectric elastomer was studied and specialized to be used in space applications. The work illustrates the research project modeling procedure adopted to simulate the mechanical behavior of this material based on a finite element theory approach. The Mooney-Rivlin’s hyperelastic and Maxwell’s electrostatic models provide the theoretical basis to describe its electro-mechanic behavior. The validation of the procedure is performed through a numerical-experimental correlation between the response of a prototype of actuator developed by the Risø Danish research center and the 3D finite element model simulations. An investigation concerning a possible application in the space environment of dielectric elastomer actuators (DEA) is also presented.

In this dissertation, three aspects about surface and interface engineering of conjugated polymers and nanomaterials will be discussed. (i) There is a significant promise for electroactive conjugated polymers (ECPs) in applications of electrochemical devices including energy harvesting, electrochromic displays, etc. Among these, ECPs has also been developed as electroactive materials in electrochemical supercapacitors (ESCs). Compared with metal oxides, ECPs are attractive because they have good intrinsic conductivity, low band-gaps, relatively fast doping-and-undoping process, the ease of synthesis, and tunable electronic and structural properties through structural modifications. Here, Multiple-branch-chain 3,4-ethylenedioxythiophene (EDOT) derivatives was designed as crosslinkers in the co-electropolymerization of EDOT to optimize its morphology and improve the cycling stability of PEDOT in the supercapacitor applications. High-surface-area π-conjugated polymeric networks can be synthesized via the electrochemical copolymerization of the 2D (trivalent) motifs benzo[1,2-b:3,4-b’:5,6-b’’]trithiophene (BTT) and tris-EDOT-benzo[1,2-b:3,4-b’:5,6-b’’]trithiophene (TEBTT) with EDOT. Of all the material systems studied, P(TEBTT/EDOT)-based frameworks achieved the highest areal capacitance with values as high as 443.8 mF cm-2 (at 1 mA cm-2), higher than those achieved by the respective homopolymers (PTEBTT and PEDOT) in the same experimental conditions of electrodeposition (PTEBTT: 271.1 mF cm-2 (at 1 mA cm-2); PEDOT: 12.1 mF cm-2 (at 1 mA cm-2). (ii) In electrochemical process, the suitable choice of appropriate electrolytes to enlarge the safe working potential window with electrolyte stability is well known to improve ECPs’ performance in ESCs applications. Ionic liquids (ILs) are ion-composed salts and usually fluid within a wide temperature range with low melting points. There are many unique characteristics for these intrinsic ion conductors, including high ionic conductivity, wide electrochemical voltage windows in neutral conditions, fast ion mobility in redox reaction process (>10-14 m2 V-1 s-1), low vapor pressure, and environmental stability. These properties qualified ambient-temperature ILs to be applied as supporting medium for various devices and materials processing applications in both industry and academia, overcoming the limitation of volatile organic compounds (VOCs). Especially, ILs have been utilized as superior medium to electrodeposit metals, alloys, semiconductors and ECPs in the application of supercapacitors. Electropolymerization of EDOT and its derivative 4,4'-dimethoxy-3,3'-bithiophene (BEDOT) have been studied in three kinds of imidazolium-based ionic liquids and conducting salt in VOCs with different anions both as the growth medium and the supporting electrolyte, to assess the influence of these anions on their morphology and electrochemical activity. It is found these thiophene polymers grown in ILs with higher viscosity and lower diffusion shows much slower growth rate and orderly morphologies than in Tetrabutylammonium hexafluorophosphate (TBAPF6) dissolved in acetonitrile (ACN), and gives better electrochemical performance via cyclic voltammetry (CV) and galvanostatic charge-and-discharge (CD) studies. Polymers displayed multiple redox peaks in several cases, the possible reasons and origins are discussed. The synthesized polymer can be affected greatly by both the ILs with different anion/cation, and its mutal interation with targeted monomer.. As far as known, there is no systematic study on how the anions of ILs and common organic solution could play a role as a medium both for polymerization and post-polymerization electrolyte for PEDOT and its derivatives. This study can be used as an easy reference and provide experimental diagnositc data when selecting ionic liquids to investigate and optimize thiophene-based electrochemical systems, such as batteries and supercapactiors. (iii) Another aspect about interface chemistry of direct functionalization of nanodiamond with maleimide has also been addressed. Functional nanodiamonds are promising candidates for extensive practical applications in surface science, photonics and nanomedicine. Here, a protocol of direct functionalization is described by which maleimide-derivatized substituents can be appended to the outer shell of thermally annealed nanodiamonds through Diels-Alder reaction. This protocol can be carried out in room temperature, ambient atmosphere, without catalyst, and provide functionalized nanodiamonds with good solubility in organic solution. Also, this method can be applied for other maleimide derivatives,e.g.m aleimide-fluorescene, which can be applied in fluorescence labeling, sensing, and drug delivery. A series of techniques, especially Fourier transform infrared spectroscopy (FTIR), and Solid State Nuclear Magnetic Resonance (SS-NMR) was conducted for the analysis of surface chemistry and the investigation of the two-point binding strategy in details.

The research work described in this PhD thesis focuses on methods and strategies of employing a polymer substrate for poly(3,4-ethylenedioxythiophene) (PEDOT) synthesis. For the purpose an ethylene vinyl alcohol copolymer (EVAL) was chosen. It offers many potentialities. Serving as mechanical support and/or functionalizable phase, it was differently combined with PEDOT to give conducting composite polymer flms or it was modified to obtain electro-active materials. Aim of the work is to show how, starting from the same base, it is possible to introduce functionalities into supported conducting systems both through the substrate and through the conducting phase, and all the strategies that were adopted.

碩士
國立交通大學
機械工程學系
98
Many novel applications of Ionic polymer-metal composite (IPMC) had been developed, such as biomimetic robotic fish and wing-like actuators, capsule-type endoscope, artificial urethral sphincter, self-switching bistable actuator, etc. For almost applications, the movement type of IPMC is in bending direction. Even though the linear actuators based on IPMC are also composed of the series connection of IPMC strips. Therefore, the linear actuation of IPMC is still bending type actuators in essence. The apparatus of IPMC have the common limitation: the lack of output force. Currently, increasing the thickness of IPMC strips seems to be an effective method to reinforce the bending force. The typical thickness of an IPMC strip is about 0.2 to 0.3 mm, and the tip force is usually less than 10 gf for the length of 4 cm. And the tip force for a 2 mm thickness IPMC strip could be reached about 20 gf. Although the increasing of force is significant, but it is expensive and requires much work and time to fabricate a specimen. In this project, an approximate linear contraction type IPMC actuator is discussed. In this project, a very thick and very narrow IPMC is introduced. And this kind of IPMC is a material saving design. According to the experiment result, the very thick and very narrow IPMC worked. But the motion type of the IPMC did not the linear type as predicted. However, this material saving design is an effective way to make a very thick IPMC by using a small amount material.