Nous étudions l'utilisation de l'électronique organique à l'interface du tissu nerveux pour des applications in vitro et in vivo. Le principal objectif est la fabrication d’interfaces neuronales flexibles pour enregistrer l'activité électrophysiologique de cellules neuronales sur de longues durées. À cette fin, nous utilisons du parylène-C comme substrat et le polymère conducteur poly(3,4-éthylène dioxythiophène):poly(styrène sulfonate) pour réduire l'impédance de l'interface cellule/électrode. En utilisant nos matrices de microélectrodes, nous montrons comment améliorer le rendement d'enregistrement avec un modèle 3D in vitro. La formation de clusters cellulaires 3D augmente considérablement le nombre d’enregistrements de potentiels d’action unitaires. In vivo, nous démontrons la fabrication de sondes de support en polymères biodégradables sur nos capteurs flexibles en utilisant une combinaison de polymères alcool polyvinylique et poly(lactique-co-glycolique). Alors que notre support d’insertion en PVA fournit la rigidité nécessaire à la pénétration, le revêtement PLGA retarde la dissolution du support afin de placer précisément les capteurs à l'intérieur du cerveau. Cela nous permet d’enregistrer en profondeur et, dans les conditions idéales, de minimiser les lésions cérébrales par rapport à les sondes traditionnelles rigides. Dans l'ensemble, nous avons réussi à effectuer des enregistrements électrophysiologiques avec nos propres microélectrodes et sondes invasives, améliorant le rendement d'enregistrements in vitro et démontrant que nos support d’insertion biodégradables pénètrent le cerveau. Ces résultats annoncent de prometteuses applications médicales futures. / Neural interfaces are designed to unravel the mysteries of the brain and to restore the functions of paralyzed patients. Despite the success of traditional neural interfaces, these rigid devices are prone to failure within months after surgery. Mechanical mismatch with the soft neural tissue is believed to be one of the main causes. In this thesis, we studied the use of soft organic electronics to interface with neural tissue for both in vitro and in vivo applications. Parylene-based microelectrode arrays (MEAs) and depth probes were made, employing the conducting polymer poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) to reduce the impedance at the cell-electrode interface. In vitro, we thereby showed how to enhance the recording yield of MEAs by creating a three-dimensional model of neurospheres. We further report on the fabrication of a new biodegradable polymer shuttle for flexible depth probes based on the combination of poly(vinyl alcohol) (PVA) and poly(lactic-co-glycolic) (PLGA). In vivo, the PVA/PLGA- shuttled probes were acutely tested in mice and revealed promising electrophysiological results. More research remains necessary to evaluate its long-term function in vivo. In conclusion, our results demonstrate that bioresorbable polymers are capable of providing the required stiffness to penetrate the brain, which shows much promise for future neural applications. This work thereby shows that a long-term functional neural interface is not far from being developed.

In this study, bulk conductivity of commercial base paper impregnated with different ionic liquids blends and additives, through bench coating was investigated. Bulk conductivity of base paper, ion conductive paper and surface sized ion conductive papers with and without the influence of calendering were evaluated at different concentrations of ionic liquids using at resistivity cell and four point probe technique. It was shown that bulk conductivity of base paper was increased by increasing the amount of ionic liquids. Nano fibril cellulose also showed positive influence on the bulk conductivity of coated papers. By increasing the line load in the calendering machine, a positive influence on the bulk conductivity was observed. The tensile index of all the coated papers was lower than that of the base paper.

O presente trabalho envolveu a eletrossíntese de três polímeros da família dos poli(p-fenilenovinileno)s, PPVs, apresentando como substituintes grupos alcóxi de cadeia longa. Esses polímeros foram caracterizados espectroscopicamente (RMN de 1H, IV e UV/VIS), termicamente (TG), por cromatografia por exclusão de tamanho (SEC), eletronicamente por voltametria cíclica e eletricamente por meio de curvas I x V em dispositivos do tipo sanduíche (metal/polímero/metal). Os polímeros foram utilizados na construção de sensores de gases para avaliação da capacidade sensitiva a vapores orgânicos, mostrando-se promissores para utilização em narizes eletrônicos. Construíram-se, também, dispositivos emissores de luz orgânicos (OLEDs) com utilização desses polímeros como camada ativa, no intuito de se conhecer sua aplicabilidade em dispositivos optoeletrônicos. Para tal, foram feitas determinações de luminância e de eficiência quântica de luminância dos OLEDs construídos. Os dispositivos do tipo sanduíche, os OLEDs e as medidas correspondentes foram realizados em Curitiba, em colaboração com o Prof. Dr. Ivo Alexandre Hümmelgen, líder do Grupo de Dispositivos Optoeletrônicos Orgânicos do Departamento de Física da Universidade Federal do Paraná. / The present work describes the electrosynthesis of three polymers of the poly(p-phenylenevinylene) (PPV) family, having at least one long chain alkoxy group as substituent. These polymers were characterized by spectroscopic analyses (1H NMR, IR and UV-Vis), thermogravimetry (TG), size exclusion chromatography (SEC), cyclic voltammetry and electrically by current vs. potential plots obtained from metal/polymer/metal sandwich devices. The polymers were tested as active layers in gas sensors for organic vapour analyses aimed for future use in electronic noses. The same polymers were also employed in organic light emitting diodes (OLEDs) in which the luminance and the luminance quantum efficiency were measured. Both the sandwich devices and the OLEDs were made in Curitiba with the collaboration of Prof. Ivo Hümmelgen, head of the Group of Organic Optoelectronic Devices at the Physics Department of the Federal University of Paraná (UFPR).

No description available.

Despite the availability of numerous two-dimensional (2D) materials with structural ordering at the atomic or molecular level, direct construction of mesoscale-ordered superstructures within a 2D monolayer remains an enormous challenge. Here, we report the synergic manipulation of two types of assemblies in different dimensions to achieve 2D conducting polymer nanosheets with structural ordering at the mesoscale. The supramolecular assemblies of amphipathic perfluorinated carboxylic acids and block co-polymers serve as 2D interfaces and meso-inducing moieties, respectively, which guide the polymerization of aniline into 2D, freestanding mesoporous conducting polymer nanosheets. Grazingincidence small-angle X-ray scattering combined with various microscopy demonstrates that the resulting mesoscale-ordered nanosheets have hexagonal lattice with d-spacing of about 30 nm, customizable pore sizes of 7–18 nm and thicknesses of 13–45 nm, and high surface area. Such template-directed assembly produces polyaniline nanosheets with enhanced π–π stacking interactions, thereby resulting in anisotropic and record-high electrical conductivity of approximately 41 S cm–1 for the pristine polyaniline nanosheet based film and approximately 188 S cm–1 for the hydrochloric acid-doped counterpart. Our moldable approach creates a new family of mesoscale-ordered structures as well as opens avenues to the programmed assembly of multifunctional materials.

Ces travaux de thèse ont permis d'élaborer un dispositif électroémissif (DEE) fin (140 µm) et flexible à base de réseaux interpénétrés de polymères (RIP). Pour ce faire, un polymère conducteur électronique, le poly (3,4-éthylènedioxythiophène) (PEDOT), est interpénétré dans une matrice hôte de manière à obtenir un système dont l'architecture monobloc est comparable à celle d'un dispositif tri-couches. Une fois le système gonflé par un liquide ionique, le 1-éthyl-3-méthylimidazolium bis-trifluorométhylsulfonylimide (EMImTFSI), les propriétés optiques du DEE sont modulables entre 24 et 51 % de réflexion dans le moyen infrarouge (bande III) en faisant varier la tension électrique appliquée aux bornes du dispositif de -1,5V à +1,5V. Les propriétés thermomécaniques du DEE proviennent essentiellement de la matrice hôte. Cette dernière est un RIP combinant la souplesse, la flexibilité et la résistance à la traction du caoutchouc nitrile (NBR) aux propriétés de conductivité ionique du poly(oxyde d'éthylène) (POE) en présence de l'EMImTFSI. / During this thesis a thin (140 µm) and flexible electroemissive device (EED), based on interpenetrating polymer networks (IPN), was elaborated. An electronic conducting polymer, poly (3,4-ethylenedioxythiophene) (PEDOT), is interpenetrated in a host matrix to obtain a system whose monoblock architecture is comparable to a three-layers device. Once the system is swollen by an ionic liquid, 1-ethyl-3-methylimidazolium bis-trifluoromethyl sulfonylimide (EMImTFSI), the EED optical properties are tunable between 24 and 51% reflection in the mid-infrared (Band III) by varying the electrical voltage applied across the device from -1.5 V to +1.5 V. The EED thermomechanical properties are mainly from the host matrix. This is an IPN combining flexibility and tensile strength of nitrile butadiene rubber (NBR) with the ionic conductivity properties of poly (ethylene oxide) (PEO) in the presence of EMImTFSI.

The thesis investigates the modification of paper into an ion- and electron-conductive material, and as a renewable material for electronic device. The study stretches from investigating the interaction between the cellulosic materials and the conducting polymer to demonstrating the performance of the conductive paper by printing the electronic structure on the surface of the conductive paper. Conducting materials such as conducting polymer, ionic liquids, and multi-wall carbon nanotubes were deposited into the fiber networks. In order to investigate the interaction between the conducting polymer and cellulosic material, the adsorption of the conducting polymer poly(3,4-ethylenedioxythiophene): poly(4-styrene sulfonate) (PEDOT:PSS) onto microcrystalline cellulose (MCC) was performed. Electroconductive papers were produced via dip coating and rod coating, and characterized. The Scanning Electron Microscopy (SEM) / Energy Dispersive Spectroscopy (EDS) images showed that the conducting polymer was deposited in the fiber and in fiber-fiber contact areas. The X-ray Photoelectron Spectroscopy (XPS) analysis of dip-coated paper samples showed PEDOT enrichment on the surface. The effects of fiber beating and paper formation, addition of organic solvents and pigments (TiO2, MWCNT), and calendering were investigated. Ionic paper was produced by depositing an ionic liquid into the commercial base paper. The dependence to temperature and relative humidity of the ionic conductivity was also investigated. In order to reduce the roughness and improve its printability, the ionic paper was surface-sized using different coating rods.  The bulk resistance increased with increasing surface sizing. The electrochemical performance of the ionic paper was confirmed by printing PEDOT:PSS on the surface. There was change in color of the polymer when a voltage was applied. It was demonstrated that the ionic paper is a good ionic conductor that can be used as component for a more compact electronic device construction. Conductive paper has a great potential to be a flexible substrate on which an electronic structure can be constructed. The conduction process in the modified paper is due to the density of charge carriers (ions and electrons), and their short range mobility in the material. The charge carrying is believed to be heterogeneous, involving many charged species as the paper material is chemically heterogeneous. / <p>Fel ordningsnummer (2010:28) är angivet på omslaget av fulltextfilen.</p> / Printed Polymer Electronics on Paper

O presente trabalho envolveu a eletrossíntese de três polímeros da família dos poli(p-fenilenovinileno)s, PPVs, apresentando como substituintes grupos alcóxi de cadeia longa. Esses polímeros foram caracterizados espectroscopicamente (RMN de 1H, IV e UV/VIS), termicamente (TG), por cromatografia por exclusão de tamanho (SEC), eletronicamente por voltametria cíclica e eletricamente por meio de curvas I x V em dispositivos do tipo sanduíche (metal/polímero/metal). Os polímeros foram utilizados na construção de sensores de gases para avaliação da capacidade sensitiva a vapores orgânicos, mostrando-se promissores para utilização em narizes eletrônicos. Construíram-se, também, dispositivos emissores de luz orgânicos (OLEDs) com utilização desses polímeros como camada ativa, no intuito de se conhecer sua aplicabilidade em dispositivos optoeletrônicos. Para tal, foram feitas determinações de luminância e de eficiência quântica de luminância dos OLEDs construídos. Os dispositivos do tipo sanduíche, os OLEDs e as medidas correspondentes foram realizados em Curitiba, em colaboração com o Prof. Dr. Ivo Alexandre Hümmelgen, líder do Grupo de Dispositivos Optoeletrônicos Orgânicos do Departamento de Física da Universidade Federal do Paraná. / The present work describes the electrosynthesis of three polymers of the poly(p-phenylenevinylene) (PPV) family, having at least one long chain alkoxy group as substituent. These polymers were characterized by spectroscopic analyses (1H NMR, IR and UV-Vis), thermogravimetry (TG), size exclusion chromatography (SEC), cyclic voltammetry and electrically by current vs. potential plots obtained from metal/polymer/metal sandwich devices. The polymers were tested as active layers in gas sensors for organic vapour analyses aimed for future use in electronic noses. The same polymers were also employed in organic light emitting diodes (OLEDs) in which the luminance and the luminance quantum efficiency were measured. Both the sandwich devices and the OLEDs were made in Curitiba with the collaboration of Prof. Ivo Hümmelgen, head of the Group of Organic Optoelectronic Devices at the Physics Department of the Federal University of Paraná (UFPR).

Organic photovoltaics (OPVs) have received a great deal of focus in recent years as a possible alternative to expensive silicon based solar technology. Current challenges for organic photovoltaics are centered around improving their lifetimes and increasing their power conversion efficiencies. One approach to improving the lifetime of such devices has been the inclusion of inorganic metal oxide layers, but interaction between the metal oxides and common conjugated polymers is not favorable. Here we present two methods by which the interactions between polythiophenes and nanostructured ZnO can be made to be more favorable. Using the first method, direct side on attachment of polythiophene to ZnO nanowires via chemical grafting, we demonstrate chemical linkage between the polymer and ZnO phases. The attachment was confirmed to affect the morphological properties of the polymer layer as well, inducing highly ordered regions of the polymer at the ZnO surface via chemical attachment and physical adsorption. Using the second method to improve polythiophene ZnO interactions, we have functionalized ZnO nanowires with organic molecules that favorably interact with conjugated polymer and organic solvents. Photovoltaic devices were made using a blended active layer of functionalized ZnO nanowires and P3HT. Electrical analysis of the resultant devices concluded that the devices were functional photovoltaic cells and isolated the dominant loss mechanisms for further device improvement.

Nanostructured porous materials generally, and nanoporous noble metals specifically, have received considerable attention due to their superior chemical and physical properties over nanoparticles and bulk counterparts. This dissertation work aims to develop well-established strategies for the preparation of multifunctional nanostructured porous materials based on the combination of inorganic-chemistry, organic-chemistry and electrochemistry. The preparation strategies involved one or more of the following processes: sol-gel synthesis, co-electrodeposition, metal ions reduction, electropolymerization and dealloying or chemical etching. The study did not stop at the preparation limits but extended to investigate the reaction mechanism behind the formation of these multifunctional nanoporous structures in order to determine the different factors controlling the nanoporous structures formation. First, gold-silica nanocomposites were prepared and used as a building blocks for the fabrication of high surface area gold coral electrodes. Well-controlled surface area enhancement, film thickness and morphology were achieved. An enhancement in the electrode’s surface area up to 57 times relative to the geometric area was achieved. A critical sol-gel monomer concentration was also noted at which the deposited silica around the gold coral was able to stabilize the gold corals and below which the deposited coral structures are not stable. Second, free-standing and transferable strata-like 3D porous polypyrrole nanostructures were obtained from chemical etching of the electrodeposited polypyrrole-silica nanocomposite films. A new reaction mechanism was developed and a new structural directing factor has been discovered for the first time. Finally, silver-rich platinum alloys were prepared and dealloyed in acidic medium to produce 3D bicontinuous nanoporous platinum nanorods and films with a nanoporous gold-like structure. The 3D-BC-NP-Pt displayed high surface area, typical electrochemical sensing properties in an aqueous medium, and exceptional electrochemical sensing capability in a complex biofouling environment containing fibrinogen. The 3D-BC-NP-Pt displayed high catalytic activity toward the methanol electro-oxidation that is 30 times higher that of planar platinum and high volumetric capacitance of 400 F/cm3. These findings will pave the way toward the development of high performance and reliable electrodes for catalysis, sensing, high power outputs fuel cells, battery-like supercapacitors and miniaturized device applications.