Preparation and properties of conducting polymer of doped polyaniline LB film

Stable monolayer of polyaniline doped with camphor sulfonic acid at the air-water interface has been obtained and has been successfully deposited by Langmuir-Blodgett technique onto CaF2 substrate. IR and UV-Vis-NIR spectra show that the doped molecules dedoped partially from the PANI backbone during the monolayer compression or deposition. Gas-sensing measurement indicates that the doped polyaniline LB film was sensitive to ethanol vapor at room temperature.

Covalently attached multilayer assemblies containing photoreactive diazo-resins and conducting polyaniline

We reported on the multilayer architecture containing diazo-resins (DAR) as polycations and polyaniline poly(aniline-co-N-propanesulfonic acid aniline) (PAPSAH) as polyanions held together by electrostatic interaction. Upon UV irradiation, the adjacent interfaces of the multilayer reacted to form a covalently crosslinking structure which greatly improved the stability of the films as confirmed by solvent etching experiments. These changes were confirmed by UV-Vis and FTIR spectroscopy. The thickness of the covalently attached films were characterized with small angle X-ray diffraction (SAXD) and a value of 30.0 Angstrom per bilayer was obtained. This type of film was further characterized by cyclic voltammetry which showed that the electroactive property of PAPSAH was still kept in the films after photoreaction. (C) 2000 Elsevier Science B.V. All rights reserved.

Poly(phenylene sulfide-tetraaniline): The soluble conducting polyaniline analogue with well-defined structures

A novel conducting polymer poly(phenylene sulfide-tetraaniline) (PPSTEA), with tetraaniline (TA) and phenylene sulfide (PS) segments in its repeat unit, has been synthesized through an acid-induced polycondensation reaction of 4-methylsulfinylphenyl-capped tetraaniline. The new polymer, which represents the first soluble conducting polyaniline analogue with well-defined structure, has high molecular weight, good solubility in common solvents, and good film-forming properties. Its electrical property is analogous to polyaniline. The conductivity of preliminarily, protonic-doping PPSTEA is up to 10 degrees S/cm. This synthetic strategy appears to be general for developing novel well-defined polyaniline analogue containing much longer fixed conjugation length.

Preparation and properties of water-based conducting polyaniline

A convenient way to make water-soluble or water-dispersible conducting polyaniline was given by employing protonic acid dopants containing hydrophilic ethyleneoxide oligomer as counter-anion. The conducting polyaniline possessed electrical conductivity in the range of 10(-3) to 10(-2) S/cm, depending on the dopant, and it displayed excellent electrochemical redox reversibility in non-aqueous system.

Preparation and properties of water-based conducting polyaniline

A convenient way to prepare water-soluble or water-dispersible conducting polyaniline was developed by employing protonic acid dopants containing hydrophilic ethyleneoxide oligomer as counter-ion. The conducting polyaniline possesses electrical conductivity in the range of 10(-3) to 10(-2) S/cm depending on the chosen dopant, and it displays an excellent electrochemical redox reversibility in non-aqueous systems.

Oxygen permeating properties of the mixed conducting membranes without cobalt

A new series of mixed conducting oxides, Sr10-n/2BinFe20Om (n = 4, 6, 8, 10), were synthesized by a solid state reaction method, and they have high oxygen permeability. The oxygen permeation rate at 1150 K is 0.41 ml(STD)/ cm(2).min for n = 6 and 0.90 ml(STD)/cm(2).min for n = 10, which is two times higher than that for Sr1-xBixFeO3 (x = 0.5). For the Sr1-xBixFeO3 (x = 0.1, 0.3, 0.5) series, the oxygen flux increases with increasing Bi content. (C) 1998 Elsevier Science Ltd.

Electrochemical investigation of DNA adsorbed on conducting polymer modified electrode

Detection of DNA is a very important task for molecular biology and biomedical field. We have investigated electrochemical behavior of double-stranded DNA and single-stranded DNA adsorbed on conducting polymer modified electrode in presence of cobalt complex. The possibility of using such electrode as gene detector is discussed.

Proton transfer across conducting polypyrrole membrane separated by two electrolyte solutions

Electrochemical behavior of the transfer of H+ across polypyrrole membrane (PPM) was studied. The transfer process was quasi-reversible and mainly diffusion-controlled. PPM electropolymerized in water solution has better reversibility than that in CH3CN solution for the transfer of H+. The transfer process of H+ across the two kinds of PPM indicated that the PPM electrochemically polymerized was of asymmetry.

Ion-conducting polymers based on modified alternating maleic anhydride copolymer with oligo(oxyethylene) side chains

Comb-like polymers (CPs) based on modified alternating methyl vinyl ether/maleic anhydride copolymer with oligo(oxyethylene) side chains of the type -O(CH2CH2O)(n)CH3 were synthesized and characterized, and complexed with lithium salts to form amorphous polymer electrolytes. Maximum conductivity close to 1.38 x 10(-4) S/cm was achieved at room temperature and at a [Li]/[EO] ratio (EO = ethylene oxide) of about 0.066. The temperature dependence of ionic conductivity suggested that the ion transport was controlled by segmental motion of the polymer, shown by linear curves obtained in Vogel-Tammann-Fulcher plots. The ionic conductivity maximum moved to a higher salt concentration as the temperature increased, indicating that a larger number of charge carriers can be transferred through polymer chains, of which free volume is increased at higher temperature. IR results indicated that the ester in CPs might decompose at 140 degrees C and reproduce the maleic anhydride ring.

New progress in conducting polyaniline

New synthesis system was established to prepare polyaniline (PAn) with controlled molecular weight. The synthesized PAn was completely soluble in many organic solvents such as dimethylsulfoxide (DMSO), dimethylformamide and N-methylpyrrolidone (NMP). The molecular aggregation due to the interaction between PAn and NMP molecules was found in dilute PAn/NMP solution. The gelatin of concentrated PAn/NMP solution was a physical crosslinking between PAn molecules with the help of NMP through hydrogen bonding. A gelatin mechanism was proposed.

Conversion from electronic conducting phase to redox conducting phase of polypyrrole

Square-wave voltommetry is used to study the oxidation of polypyrrole doped with dodecylsulfate. The net current curve in this experiment shows why the oxidation current does not display the capacitive-like shape common in cyclic voltammetry. In cyclic voltammetry, the redox behavior of polypyrrole is attributed to the size of dodecylsulfate, irreversible incorporation and the complete consumption of dodecylsulfate. After the polypyrrole film was scanned in aqueous NaCl solution, square wave voltammetric measurements show different results, indicating the change of the polymer nature with regard to the charge transport. This is explained by anion replacement, exclusion and the change of the charge transport mechanism.

Lithium ion conducting polymer electrolytes based on alternating maleic anhydride copolymer with oligo-oxyethylene side chains

A comb polymer with oligo-oxyethylene side chains of the type -(CH2CB2O)(12)CH3 was prepared from methyl vinyl ether/maleic anhydride copolymer and poly (ethylene glycol) methyl ether. The polymer can dissolve LiClO4 salt to form homogeneous amorphous polymer electrolyte. The ac ion conduction was measured using the complex impedance method, and conductivities were investigated as functions of temperatures and salt concentration. The complexes were first found to have two classes of glass transition which increase with increasing salt content, The optimum conductivity attained at 25 degrees C is in the order of 5.50 x 10(-6)Scm(-1). IR spectroscopy was used to study the cation-polymer interaction.

Research on modified electrode of conducting polymer .2. Characteristics of polypyrrole film doped with heteropolyanions

Polypyrrole film electrode with Co(W2O7)(6)(10-) and CuW12O406- ions were synthesised in aqueous solutions, The electrode possesses a good stability and cyclic voltammetric behavior in weakly acidic or near neutral solutions, The redox of CuW12O406- ion can be catalysed by the polypyrrole film, The ESR measurement of the polypyrrole film with Co(W2O7)(6)(10-) and CuW12O406- ions indicates that the heteropolyanions not only play the role of neutralizing electricity in the polypyrrole film, contrasted with the film containing NO3-, but also Interact with the polypyrrole molecular chain to form some additive compound, The additive compound affects the electric structure elf the polypyrrole film and is unstable at more positive or more negative potentials.

Study on the modified electrode of conducting polymers .3. Electron spin resonance characteristic of polypyrrole film electrode doped with heteropolyanions

The ESR of PPy films doped with Co (W2O7)(6)(10-) and CuW12O406- ions were reported and discussed. Results show that heteropolyanions not only play the role of neutralizing electricity in the PPy film, but also interact with the PPy molecular chain to form some adducts. The adducts affect the electronic structure of the PPy film and are unstable at more positive or more negative potentials. Dysonian ESR lineshape was recorded for the dry PPy film with CuW12O406- for the first time.

ATTEMPTS TO MODIFY AN ELECTRODE WITH A CONDUCTING PLATINUM CLUSTER COMPOUND

A conducting platinum cluster compound K1.64Pt(C2O4)(2) was electrochemically synthesized on a glassy carbon electrode through the electrooxidation of K2Pt(C2O4)(2) in an aqueous medium using single potential step and cyclic voltammetry methods. The precursor K2Pt(C2O4)(2) was prepared by a ligand exchange reaction between C2O42- and PtCl42-. During single potential step experiments, the electrolytic current corresponding to the oxidation of K2Pt(C2O4)(2) increased dramatically after a sharp decrease at the beginning (due to the formation of conducting K1.64Pt(C2O4)(2) on the surface of the working electrode). Two kinds of mechanism account for the current transients at the different applied potentials. Cyclic voltammetry was conducted with K1.64Pt(C2O4)(2) on the surface of the working electrode and a steady-state diffusion current was observed. Since the material grew in a fibrous manner, each conducting fiber which was in contact with the electrode could serve as an ultramicroelectrode. The behavior of the working electrode was thus changed from a plain to an ultramicroelectrode array.