Hideyuki Masuda

Synthesis and properties of 3-substituted polypyrroles

Abstract Films of polypyrrole(PPY), poly(3-methylpyrrole) (PMPY), poly(3-octylpyrrole)(POCPY), poly(3-propanoylpyrrole)(PPRNPY), and poly(3-phenylpyrrole)(PPHPY) were electrochemically prepared and their properties were compared. PPY was the most highly conducting and the stablest in a doped state. POCPY was soluble in common organic solvents. Its oxidation potential and interband transition energy were higher than that of PPY. Conductivity of PPRNPY was as low as 0.3 S/cm. Different from poly(3-phenyl-thiophene), the substitution with phenyl groups did not reduce oxidation potential and interband transition energy.

Electrochemical polymerization of 3-dodecylthiophene: Effect of current density and film thickness

Abstract Poly(3-dodecylthiophene) (PDDT) films are electrochemically prepared and their conductivities examined. At a constant charge density, the conductivities of PDDT films are dependent on the current density, but in fact its effect should be attributable to a change in film thickness. At a constant current density, the conductivity of films decreases with an increase in charge density below 1.2 C/cm 2 . Above this, it is nearly independent of the charge density. There is a similar tendency in the relationship between conductivity and thickness. The molecular weight increases with an increase in the current density and crosslinking reactions take place at high current densities. In the scanning electron micrographs (SEM) of freestanding films, projections are observed on the film surfaces, and grow as the electrochemical polymerization proceeds. The surface of a 0.1 μm thick film on a substrate is smooth, but at high magnification there are many bumps, due to nucleus-centred growth. A scheme that explains the processes of film growth and dependence of conductivity on film thickness is proposed.

Comparative study on poly(3-alkylpyrroles)

Polypyrrole(PPY), poly(3-methylpyrrole)(PMPY) and poly(3-octylpyrrole) (POCPY) were prepared under the same electrochemical polymerization conditions and their properties were comparatively studied. Electrical conductivity increased in the order POCPY < PMPY < PPY. Absorption spectra measuredin situ showed that while peak energy of the interband transition increased in the order PPY < PMPY < POCPY, the absorption edge of PPY was located at almost equal energy as that of PMPY and POCPY. Stability, indicated by decrease in the ratio of conductivities after storage to the initial conductivity, was primarily dependent on the length of alkyl chains, secondly on dopants and associated with spectral deterioration. While the initial conductivity was strongly dependent on temperature and current density during electrochemical polymerization, the stability was virtually independent of these conditions. The stability increased in the order: POCPY < PMPY < PPY. Spectral change during storage in air was dependent on the chemical structure of polymers but almost independent of dopants. The spectral change indicated PPY to be in nearly initial states after 10 days and POCPY to be in almost completely undoped states after 200 days. In cyclic voltammograms, PPY and POCPY showed one anodic peak and PMPY two anodic peaks. Their peak potentials were associated with conjugation length.

Electrochemical polymerization of thiophene bearing various silyl substituents

Abstract Electrochemical polymerization of bis(2-thienyl)dimethylsilane (BTMS), 1,2-bis(2-thienyl)tetramethyldisilane (BTMDS), bis(2-thienyl)diphenylsilane (BTPS), and 2,5-bis(trimethylsilyl)thiopene (BTMST) was studied. These thiophenes bearing silyl substituents produced conducting polymer films which showed IR spectra, optical absorption spectra, and cyclic voltammograms identical to the films prepared from thiophene. However, SEM photographs showed morphological difference between the films from the silyl-substituted thiophenes and from thiophene.

ELECTROCHEMICAL PREPARATION OF POLY(3-PROPANOYLPYRROLE) AND POLY(3-PHENYLPYRROLE)

Abstract Two pyrrole derivatives, 3-propanoylpyrrole (PRNPY) and 3-phenylpyrrole (PHPY) have been prepared. Electrochemical polymerization of these compounds yields a film on the anodic surface. Conductivities of poly-PRNPY (PPRNPY) and poly-PHPY (PPHPY) are 0.3 and 1 S/cm, respectively. The oxidation potential of PPRNPY is remarkably higher than that of polypyrrole, because of the lowering of the valence band energy by the electron-withdrawing acyl group. However, the bandgap is smaller. The addition of the phenyl group to pyrrole rings does not reduce the interband transition energy, indicating that the steric effect is dominant in PPHPY. These results show that the oxidation potential and the absorption edge of polypyrrole can be adjusted over a wide range by the addition of various substituents to the polymer backbone.

Chemical and Electrochemical Syntheses of Soluble Electroconducting Poly(2,5-Thienylene) Derivatives

Abstract Soluble electroconducting poly[3 -(ω-phenylalkyl)-2,5 -thienylene)]s are synthesized by electrochemical and chemical polymerizations of 3-(2-phenylethyl)thiophene and 3-(3-phenylpropyl)thiophene, which are synthesized by a Grignard cross-coupling reaction of l-bromo-3-phenylalkane with 3-bromothiophene in the presence of dichloro[1,3-bis(diphenylphosphino)propane]-nickel(II). The chemical, electrochemical, and electrical properties of these polymers are reported, including initial characterization, spectroscopy, and electrochemical cyclic voltammetry.

Soluble conducting polypyrrole: poly(3-octylpyrrole)

Electrochemical polymerization and oxidative coupling of 3-octylpyrrole yielded a soluble and conducting polymer which showed characteristics different from poly(3-alkylthiophenes) and poly(3-methoxythiophene).

Electrochemical polymerization of pyrrole with water-soluble polymeric electrolytes

Summary form only given. We report the dehalogenative polymerization of methyl 1, 4-dichloro- benzoate (MDCB) and methyl 2,5-dichlorothiophene carboxylate (MDCTC), and its hydrolysis to poly(sodium paraphenylene carboxylate) (PSPC) and poly(sodium thiophene-3-carboxylate) (PSTC) that are useful for the electrochemical polymerization of pyrrole. The degree of polymerization of PMPC and PMTC were 40 and 18, respectively. These polymers were soluble in water. Electrochemical polymerization of pyrrole was carried out in water with PSPC and PSTC, and the conductivities of polypyrrole films were 1.3 and 0.24 S/cm, respectively. By using PSPC and PSTC gave conducting films, it is suggested that PSPC and PSTC are interesting polymeric electrolytes.