Showing papers on "Conductive polymer published in 1999"
TL;DR: The construction of controlled architectures based on spatially segregated multilayers, exhibiting complementary biological activities is described, and the attachment of biomolecules to biotinylated polymers through affinity interactions based on avidin-biotin bridge is presented.
731 citations
TL;DR: Chronopotentiometry is found to be a convenient and fast experimental method to critically evaluate the potential stability of different types of ion-selective electrodes.
Abstract: Demanding analytical applications such as on-line process analysis and clinical analysis require robust, reliable, and maintenance-free ion sensors of high potential stability. In this work the stability of the electrode potential of all-solid-state ion-selective electrodes using conducting polymers as ion-to-electron transducers is critically evaluated by using chronopotentiometry and electrochemical impedance spectroscopy. This study is focused on the relationship between the potential stability of the electrode and the capacitance of the solid contact where ion-to-electron transduction takes place. The influence of this capacitance on the potential stability of all-solid-state ion-selective electrodes is studied experimentally by using conducting polymer layers of different thickness as solid contacts in potassium ion-selective electrodes based on a solvent polymeric membrane. Because of its excellent environmental stability, the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is used as a model compound for the solid contact material. Chronopotentiometry is found to be a convenient and fast experimental method to critically evaluate the potential stability of different types of ion-selective electrodes.
550 citations
TL;DR: In this paper, the authors report electroabsorption measurements of polymer light-emitting diodes, (LEDs), fabricated with poly(4-4′-diphenylene dioxythiophene), PDPV, as the emissive layer, Ca-Al cathodes, and indium tin oxide (ITO) anodes, with and without a doped conducting polymer hole injection/transport layer.
Abstract: We report electroabsorption measurements of polymer light-emitting diodes, (LEDs), fabricated with poly(4-4′-diphenylene diphenylvinylene), PDPV, as the emissive layer, Ca–Al cathodes, and indium tin oxide (ITO) anodes, with and without a doped conducting polymer hole injection/transport layer, namely poly(3,4-ethylene dioxythiophene), PEDOT, doped with poly(styrene sulfonate), PSS−. In these structures, the bias at which the electroabsorption signal is null corresponds to the difference between the electrodes’ work functions. We find that such a built-in voltage increases by 0.5 V when a PEDOT:PSS film is incorporated between the ITO electrode and the emissive layer. This leads to a marked reduction of the anode barrier height at the hole-injecting interface, and accounts for a variety of improvements brought about by the PEDOT insertion, namely: (a) the increase of luminescence efficiency, (b) the reduction of the turn-on voltage, and (c) the increase of the device lifetime.
529 citations
TL;DR: The physical and chemical properties of a new class of lithium conducting polymer electrolytes formed by dispersing ceramic powders at the nanoscale particle size into a poly(ethylenoxide) (PEO)− lithium salt, LiX complexes, are reported and discussed in this paper.
Abstract: The physical and chemical properties of a new class of lithium conducting polymer electrolytes formed by dispersing ceramic powders at the nanoscale particle size into a poly(ethylenoxide) (PEO)− lithium salt, LiX complexes, are reported and discussed. These true solid-state PEO−LiX nanocomposite polymer electrolytes have in the 30−80 °C range an excellent mechanical stability (due to the network of the ceramic fillers into the polymer bulk) and high ionic conductivity (promoted by the high surface area of the dispersed fillers). These important and unique properties are accompanied by a wide electrochemical stability and by a good compatibility with the lithium electrode (assured by the absence of any liquids and by the interfacial stabilizing action of the dispersed filler), all this making these nanocomposite electrolytes of definite interest for the development of advanced rechargeable lithium batteries.
490 citations
TL;DR: In this article, the most important examples from the major classes of organic electrochromic materials, namely the 1,1′-disubstituted-4,4′-bipyridilium salts (the ''viologens'), conducting polymers, metallopolymers and metallophthalocyanines are reviewed.
482 citations
TL;DR: The state of the art of novel electronically conducting polymeric materials is presented in this article, where the special emphasis is laid on the electrochemical synthesis of conducting polymers (CPs) including the choice of the monomers and solvents, supporting electrolytes and electrodes and structural aspects of these novel materials and the nature of the dopants which induce electrical conductivity in conjugated organic polymers.
442 citations
386 citations
TL;DR: In this paper, the properties of PEDOT-PSS have been studied using X-ray and ultraviolet photoelectron spectroscopy, focusing on thermal effects and the influence of hydrochloric acid on the chemical and electronic structures of the films.
386 citations
TL;DR: In this article, it is shown that the combined mechanical, thermal and electrical interaction between the filler particles via their electrical contacts and the surrounding polymer host matrix are responsible for the properties of the composite material.
Abstract: Conducting polymer composites become increasingly important for technical applications. In this article, the resulting electrical properties of such materials are illustrated by a variety of experimental examples. It is shown that the combined mechanical, thermal and electrical interaction between the filler particles via their electrical contacts and the surrounding polymer host matrix are responsible for the properties of the composite material. A short review is given of the theoretical background for the understanding of the electrical transport in such materials. The arrangement of the filler particles and the resulting conductivity can be described either by percolation or by effective medium theories. It can also be related to different types of charge carrier transport processes depending on the internal composite structure. Special emphasis is given to the microstructure of the filler particles such as size, hardness, shape and their electrical and thermal conductivities. A detailed analysis of the physics of the contact spots and the temperature development during current flow at the contact is given. It is shown that the polymer matrix has a strong influence on the electrical conductivity due to its elastic properties and the response to external thermal and mechanical stimulation. Strong changes in the electrical conductivity of conducting polymer composites can be realized either by thermal stimuli, leading to a positive and negative temperature coefficient in resistivity, or by applying mechanical stress. By using nonlinear fillers an additional degree of functionality can be achieved with conducting polymers.
381 citations
TL;DR: A brief review on electrocatalysis and heterogeneous catalysis at conducting polymers is presented in this article, where the topics covered include: electrocatalysts at conducting polymer electrodes (quinone-hydroquinone redox couple, organic compounds of analytical interest, various electroorganic reactions, inorganic ions), electrocatalysings at polymer electrodes, modified with dispersed metals, heterogeneous Catalysis and Electrocatalysis at polymers, doped with heteropolyanions, and various metal complexes.
318 citations
TL;DR: Electrochemically synthesized composites comprising heparin and the electrically conducting polymer polypyrrole had a shelf life of at least 2 years postautoclaving and were found to be excellent substrates for the growth of human endothelial cells.
Abstract: Heparin is a potent anticoagulant which can be immobilized on biomaterial surfaces to increase their hemocompatability. In the present work, we have electrochemically synthesized composites comprising heparin and the electrically conducting polymer polypyrrole. The incorporation and exposure of heparin were controlled by varying key conditions of polymer synthesis (i.e., applied current and synthesis time). The resulting composite polymers were electroactive after synthesis and the amount of heparin exposed in the polymer could be increased (up to threefold) by switching the polymers from their oxidized to reduced states. Polymer reduction was achieved by either application of negative potentials (-0.4 to -0.7 V for 90 s) or exposure to aqueous reductant (0.1M sodium dithionite for 30 min). Heparin-polypyrrole composites remained stable after autoclaving, displaying no significant loss of electroactivity, and had a shelf life of at least 2 years postautoclaving. Finally, the composites were found to be excellent substrates for the growth of human endothelial cells.
TL;DR: In this article, a review of functional conjugated polymers prepared by electrochemical polymerization is presented, focusing on the thiophene-based polymers and the relationships between the structures of derivatized precursors, their aptitude for electropolymerisation and the electronic properties of the resulting polymers.
Abstract: Functional conjugated polymers prepared by electrochemical polymerization are reviewed. Various classes of functionalized polymers are considered such as polymers for energy storage and sensor applications, small band gap polymers and novel polymeric materials with original macromolecular structure. Particular emphasis is placed on the thiophene-based polymers and on the relationships between the structures of the various kinds of derivatized precursors, their aptitude for electropolymerisation and the electronic properties of the resulting polymers.
TL;DR: In this article, the application of the scanning reference electrode technique (SRET) to the study of PANI coatings on carbon steel was described, and it was shown that conductive PANI passivates pinhole defects in coatings applied to carbon steel and is more effective for corrosion protection than sulfonic acid salts.
Abstract: Growing environmental concerns regarding the use of heavy metals in coating formulations have lead to a new coating strategy employing inherently conducting polymers (ICPs), such as polyaniline (PANI), as a key component. The principal potential advantage offered by the ICP coating technology is toleration of pinholes and minor scratches. This paper describes the application of the scanning reference electrode technique (SRET) to the study of PANI coatings on carbon steel. SRET results demonstrate that conductive PANI passivates pinhole defects in coatings on carbon steel. In addition, it is shown that phosphonic acid salts of PANI are more effective for corrosion protection than sulfonic acid salts. A model is proposed which entails passivation of the metal surface through anodization of the metal by PANI and formation of an insoluble iron-dopant salt at the metal surface.
TL;DR: In this article, the effect of blended and layered titanium dioxide (TiO2) nanoparticles on charge transfer processes in conjugated polymer photovoltaics was studied. And the results for the layered morphologies are consistent with charge collection by exciton diffusion and dissociation at the TiO2 interface.
Abstract: We study the effect of blended and layered titanium dioxide (TiO2) nanoparticles on charge transfer processes in conjugated polymer photovoltaics. A two order of magnitude increase in photoconductivity and sharp saturation is observed for layered versus blended structures, independent of the cathode work function. Using electrodes with similar work functions, we observe low dark currents and open circuit voltages of 0.7 V when a TiO2 nanoparticle layer is self-assembled onto the indium–tin–oxide electrode. Our results for the layered morphologies are consistent with charge collection by exciton diffusion and dissociation at the TiO2 interface.
TL;DR: In this paper, the thickness and electrical properties of polyaniline hydrochloride films were determined by optical interferometry and linked to their optical absorption at the wavelength 400 nm, A 400 =(5.4±0.2)×10 −3 d f (in nm).
TL;DR: In this article, the authors synthesized polyaniline-Na+-montmorillonite nanocomposite particles using an emulsion intercalation method and prepared electrorheological (ER) fluids by dispersing the synthesized nanoparticles in an electrically insulating silicone oil.
Abstract: We synthesized polyaniline-Na+-montmorillonite nanocomposite particles using an emulsion intercalation method and prepared electrorheological (ER) fluids by dispersing the synthesized nanocomposite particles in an electrically insulating silicone oil. The conducting polymer (polyaniline) was inserted into the layers of clay, and this insertion of polyaniline was confirmed by X-ray diffraction. For the first time, ER properties were determined via a rotational rheometer equipped with a high voltage generator.
TL;DR: Saricci et al. as mentioned in this paper presented efficiency data of solar cells based on a soluble derivative of p-phenylene vinylene (PPV), poly [2-methoxy, 5-(3′,7′-dimethyl-octyloxy)]-p-phenylon vinylene, and a highly soluble methanofullerene, [6,6]-phenyl C61-butyric acid methyl ester (PCBM), embedded into a conventional polymer, polystyrene (PS).
Abstract: Bulk donor–acceptor heterojunctions between conjugated polymers and fullerene derivatives have been utilized successfully for photovoltaic devices showing monochromatic energy conversion efficiencies above 1%. The photovoltaic response of these devices is based on the ultrafast, photoinduced electron transfer from the conjugated polymer to the fullerene [N. S. Sariciftci and A. J. Heeger, Handbook of Organic Conductive Molecules and Polymers, (Wiley, New York, 1997), pp. 413–455]. In this work we present efficiency data of solar cells based on a soluble derivative of p-phenylene vinylene (PPV), poly [2-methoxy, 5-(3′,7′-dimethyl-octyloxy)]-p-phenylene vinylene (MDMO-PPV), and a highly soluble methanofullerene, [6,6]-phenyl C61-butyric acid methyl ester (PCBM), embedded into a conventional polymer, polystyrene (PS). By the blending of the optimized donor–acceptor components into the conventional polymer matrix, the percolation threshold for photovoltaic response of the three component systems is found to be determined by percolation of the methanofullerene in the polymer matrix. We present current/voltage data of PS–MDMO-PPV–PCBM devices with various PS concentrations as well as photoinduced absorption studies in the infrared [(PIA) Fourier transform infrared] and light induced electron spin resonance studies on the electron transfer in these composites. At low light intensities, the monochromatic power conversion efficiency ηe and the photon carrier collection efficiency ηc of the PS free device are calculated with 1.5% and 18%, respectively.
TL;DR: A review of the options available for immobilisation of biocomponents and signal generation using conducting polymer-based biosensors can be found in this article, where a range of biological moieties (enzymes, antibodies and even whole living cells) are incorporated into the polymer structure.
Abstract: Conductive electroactive polymers are materials discovered just on two decades ago. Originally heralded for their high conductivity/weight ratio, it is the unique chemical properties they possess that now arouse much attention. The ability to synthesise these materials under mild conditions enables a range of biological moieties (enzymes, antibodies and even whole living cells) to be incorporated into the polymer structure. The unique electronic properties then allow direct and interactive communication with the biochemistries incorporated to produce a range of analytical signals. This work reviews the options available for immobilisation of biocomponents and signal generation using conducting polymer-based biosensors.
TL;DR: In this article, the conjugated polymer polypyrrole and gold bilayers are used as hinges to lift rigid components, such as silicon plates produced by reactive ion etching.
Abstract: The conjugated polymer polypyrrole undergoes a volume change of several percent when its oxidation state is changed electrochemically by the application of voltages between 0 and -1 V (versus Ag/AgCl). This volume change is due to ion movements in or out of the polymer film. Bilayers of polypyrrole and gold undergo a large bending and can deliver high force. They can thus function as hinges to lift rigid components. In this work, we demonstrate that silicon plates produced by reactive ion etching can be lifted by such PPy/Au hinges. The strength and efficiency of these bilayers are also determined.
TL;DR: Poly(3,4-ethylenedioxythiophene)/poly(styrene-4-sulfonate) (PEDOT/PSS) composites have been prepared from aqueous and acetonitrile solutions of EDOT and NaPSS by oxidation using Fe(III) salts as mentioned in this paper.
Abstract: Poly(3,4-ethylenedioxythiophene)/poly(styrene-4-sulfonate) (PEDOT/PSS) composites have been prepared from aqueous and aqueous acetonitrile solutions of EDOT and NaPSS by oxidation using Fe(III) salts. Powders with PEDOT to PSS ratios ranging from 0.3 to 4.2 and electronic conductivities as high as 10 S cm-1 have been obtained in good yields. The PEDOT/PSS blends are cation exchangers and exhibit facile eletrochemistry in both aqueous and acetonitrile media. Impedance measurements have shown that 30 μm thick PEDOT/PSS layers have proton conductivities as high as 0.03 S cm-1.
TL;DR: Conjugated organic polymers can be doped, via oxidation or reduction chemistry or via acid-base chemistry, to induce very high electrical conductivity as mentioned in this paper, and they are beginning to find use.
TL;DR: In this article, an inclusion complex formation between polyaniline with emeraldine base and β-cyclodextrin was studied by the frequency-domain electric birefringence (FEB) spectroscopy in a solution of N-methyl-2-pyrrolidone (NMP) and by scanning tunneling microscopy (STM).
Abstract: Inclusion complex formation between polyaniline with emeraldine base and β-cyclodextrin has been studied by the frequency-domain electric birefringence (FEB) spectroscopy in a solution of N-methyl-2-pyrrolidone (NMP) and by scanning tunneling microscopy (STM). The FEB results show that polyaniline in the solution with cyclodextrin changes its conformation from coil to rod at low temperature (below 275 K), and some rodlike images are observed on a substrate by STM. These results suggest that cyclodextrins are threaded onto polyaniline and confine the conformation of the polymer chain to a rodlike one. Furthermore, it is found that the threaded cyclodextrins prevent the chemical oxidation, i.e., doping of polyaniline by iodine. This indicates formation of a new inclusion complex, a conjugated conducting polymer covered by insulated cyclic molecules, namely, “insulated molecular wire”.
TL;DR: In this paper, the PANI-PVP composites were characterized microscopically, by transmission electron microscopy (TEM), for the prepared dispersion or solution of PANI in the presence of PVP, and by scanning electron microscope (SEM) for selected isolated PANI composites.
TL;DR: In this article, the influence of the ITO work function on the band alignment in semiconducting polymer over-layers was studied using UPS, and it was shown that the barrier to hole injection is determined by the work function of the conducting polymer instead of ITO.
TL;DR: In this article, a SiO2/PEO (Polyethylene Oxides) hybrid membrane was found to be thermally stable at high temperatures because of the inorganic SiO 2 framework in the composites matrix.
TL;DR: In this paper, a protonic conducting membrane was found to be thermally stable at high temperatures because of the inorganic SiO2 framework in the nanocomposite matrix.
TL;DR: In this paper, high piezoresistive conducting polyaniline-titanium oxide (PANI/TiO2) composites have been synthesized by ''in situ'' deposition technique by placing the fine grade powder (average particle size of approximately 100 nm) of anatase TiO2 in the polymerization reaction mixture of aniline.
TL;DR: In this article, a new type of carbon nanotube (CNT) (diameter of <100 nm) coated by conducting polypyrrole (PPY) was synthesized by in situ polymerization on CNTs.
Abstract: A new type of carbon nanotube (CNT) (diameter of <100 nm) coated by conducting polypyrrole (PPY) was synthesized by in situ polymerization on CNTs. The structure of the resulting complex nanotubes (CNT-PPY) was characterized by elemental analysis, X-ray photoelectron spectroscopy, Raman spectra, and X-ray diffraction. These indicated no significant chemical interaction between PPY and the CNT. The electrical, magnetic, and thermal properties of the complex nanotubes were measured and showed the physical properties of the CNTs were modified by conducting PPY. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2605–2610, 1999