Toshiyuki Ohsawa

Electrical and Optical Properties of Electrochemically Prepared Polyfuran

Polyfuran films are prepared electrochemically and found to exhibit electrical and optical properties similar to those of polythiophene and polypyrrole, though the electrical conductivity in a doped state is little lower than the latter two polymers. The resistivity of polyfuran is found to be very sensitive to humidity and its application as a sensor of humidity is proposed.

Ion rechargeable batteries using synthetic organic polymers

Abstract We have newly developed multi-porous sheets fabricated from chemically polymerized polyaniline which are applicable for positive electrodes of ion rechargeable batteries. We have also developed novel multi-porous sheets for negative electrodes made of carbon material which are derived from synthetic organic polymer. Both sheets fabricated to have an area of maximum 1000cm 2 and thickness of 0.3∼3.0mm are reinforced by synthetic short fiber. Because of fiber-reinforcement, these sheets show excellent mechanical properties and easy handling in spite of their high porosity. The polyaniline positive electrodes have been combined with the carbon negative electrodes to produce high energy density cells having excellent cycle life and a high working voltage. Preliminary prototype CR 2016 cells made of these electrodes in welded steel can have demonstrated up to 17 mWh/cell.

Application and Characteristics of Conducting Polymer as Radiation Shielding Material

Conducting polymers with high electrical conductivity like doped polypyrrole are used successfully as radiation shielding meterials. They are especially effective to shield an electric field with an attenuation higher than 30 dB in the range of 3 MHz–300 MHz with doped polypyrrole of 35 µ thickness, bu not effective for shielding a magnetic field with attenuation less than 10 dB in the same range.

Polaronic transition in electrochemical polymerized polyaniline

Abstract Polyaniline films prepared by electrochemical polymerization in sulfuric acid show stability for doping (energy density 140–160 Ah/kg) and undoping in non-aqueous electrolyte by choosing suitable conditions. According to cyclic voltammetry with lower potential sweep rates (

Electrochemical polymerization of benzene utilizing boron trifluoride ethyl ether complex

Abstract Flexible poly-(p-phenylene) films were synthesized by the electrochemical polymerization technique from benzene utilizing boron trifluoride ethyl ether complex on glassy carbon (GC) or In-Sn oxide coated conducting glass (ITO) electrodes. The obtained films exhibit electrochemical oxidation-reduction in propylene carbonate (PC) containing KPF6. As-grown and doped films indicate high electrical conductivity (>1 S/cm) which is remarkably reduced by undoping (10−8 S/m), and the band gap of the undoped sample is evaluated to be 2.1 eV from the absorption spectrum.

In Situ Conductivity, Electron Spin Resonance and Absorption Spectra Measurements in Polyaniline During Electrochemical Doping

In in situ measurements of ESR during electrochemical doping in polyaniline, the maximum spin density is observed at 3.25 V. ESR linewidth decreases upon doping, but after exhibiting a minimum value at 3.5 V, it increases again, tending to saturation. On the other hand, in situ conductivity measurement demonstrates the maximum value (1.6 S/cm) at around 3.5 V. Taking into consideration the complex absorption spectral change upon doping, the results are discussed in terms of polaron and bipolaron models. At higher doping levels, suppression of the interchain transfer of polaronic species due to Coulomb interaction is introduced to explain the decrease of conductivity.

A Comparative Study Of D-C Electrochemiluminescence from Poly(2-methoxy-5-dodecyloxy-p-pheynylenevinylene) in Solution and in Solid Polymer Electrolyte Media

D-C electrochemiluminescence (ECL) of poly(2-methoxy-5-dodecyloxy- p-pheynylenevinylene) was observed for the film immersed in an electrolytic solution and for its dry composite film with a solid polymer electrolyte using interdigitated gold electrodes spaced 5 µ m apart. The coincidence of the onset voltages and spectra of the ECL suggests that both ECLs can be interpreted by the same mechanism: negatively and positively charged excited species of the polymer are formed at the cathode and anode, respectively, and recombine between the electrodes to form singlet excitons which radiatively relax to the ground state.

An ESR study on polyaniline in nonaqueous electrolyte

Abstract ESR measurements were performed for polyaniline (PANI) at various doping levels electrochemically controlled in aprotic conditions, LiBF4/PC-DME and LiAsF6/PC-DME. Spin density and linewidth in the ESR spectrum of LiBF4-doped PANI (PANI/BF4−) change dramatically at c. 3.2 V versus Li/Li+ indicating the formation of bipolarons. On the contrary, the variation of the ESR spectrum of LiAsF6-doped PANI (PANI/AsF6−) in the same potential range is less clear. This corresponds to the fact that the change in spectrum and electrical conductivity of PANI/AsF6− is much slower up to highly positive potentials, which is explained in terms of high stability of the polaronic state. Effects of O2 and H2O on the ESR signal of PANI/BF4− are significant; linewidth of the signal changes reversibly by reacting with O2 and H2O without change in conductivity, suggesting a facile relaxation of the polaronic spins by interacting with paramagnetic spins of O2.

Non-linear electric properties of polyaniline doped with organic acceptors

Abstract Complexes of polyaniline (PANI) with various organic r -electron acceptors such as TCNQ and others were prepared by the automatic doping method. The relationship between current and applied voltage was linear and ohmic in argon atmosphere at voltages below 5 V, but in air it was non-linear. A field-effect current was observed at PANI-chloranil complex on silicon substrate.

Preparation of Glass-Conducting Polymer Composite by Sol-Gel Method and Its Property

Simple methods to obtain composite glass with conducting polymers by the sol-gel method have been developed. Poly(2,5-diethoxy aniline)-glass composite is prepared by gelation of a sol containing a polymer. Polypyrrole-glass composite is made by polymerization of pyrrole in the premade glassy medium with FeCl3 as a catalyst. Electrical and optical properties of the obtained composites have been studied.