Bernd Krische

Chemical synthesis and characterization of soluble poly(4,4′-dialkyl-2,2′-bithiophenes)

Abstract Chemical polymerization of 4,4′-dialkyl-2,2′-bithiophenes is reported. The resulting soluble polymers can be cast from their chloroform solutions to give thin layers and free-standing films, which can be doped by electrochemical and chemical methods. Cyclic voltammetry and 1 H nuclear magnetic resonance spectroscopy give evidence of better stereoregularity of the polymers obtained from disubstituted bithiophenes as compared to those obtained from 3-substituted thiophenes.

Polymerization of pyrrole on polyether, polyester and polyetherester-iron(III) chloride coordination complexes

Abstract Poly(ethylene oxide) (poly(oxy-1,2-ethanediyl)), polyester (poly(β-propiolactone) or poly(2-oxetanone)) and polyetherester (poly(1,5-di-oxepan-2-one)) form highly viscous liquid complexes with iron(III) chloride at a weight ratio of polymer/FeCl3 equal to 7:3. These complexes placed in the vapour of pyrrole initiate its polymerization. Polypyrrole composites obtained in this way have conducting properties of 2–3 × 10−3 S cm−1. However, their electroactivity differs very much depending on the polymer-FeCl3 complex used for polymerization. These polypyrrole composites exhibit increased conductivity under UV (254 nm) irradiation. Polypyrrole polymerized on poly(ethylene oxide)-FeCl3 complex has very good electrochemical properties and shows very promising features such as high activity and high reversibility of the active material. Polymerization of pyrrole on polymer-FeCl3 complexes is a very useful method, because it is achieved without electrodes and supporting electrolytes. The morphological structures of polypyrrole composites differ very much depending on the polymer-FeCl3 complex used for pyrrole polymerization. UV-Vis, FT-IR, ESCA, Mossbauer and ESR spectroscopies and SEM microscopy have been employed to study the structure of polypyrrole composites.

Conducting polymers from dimethyl-2,2′-bithiophenes

Electrochemical oxidation of symmetrical dimethylbithiophenes with free α-positions yields electroactive polymers with excellent cycling ability.

Polythiophene synthesis by electropolymerization of thiophene and bithiophene

Abstract The electropolymerization of thiophene and bithiophene has been studied with cyclic voltammetry. The influence of oligomers and protons on threshold and polymerization potentials has been examined. The interpretation of the experimental results differs significantly from that presented recently by Tanaka et al. ( Synth. Met., 24 (1988) 203).

Bithiophenes as starting monomers for polythiophene syntheses

Abstract Bithiophenes, when used as starting material for polythiophene synthesis, offer advantages over corresponding thiophenes. Polymerization proceeds at lower oxidation potentials and lower monomer concentration and gives polymers with higher yield and better regularity as shown by cyclic voltammetry and 1H NMR spectroscopy.

Improved electrochemical oxidation of polyacetylene

Abstract The influence of additives on the electrochemical oxidation of polyacetylene in acetonitrile and dichloromethane has been evaluated. Of the ten tested substances only bithiophene showed a significant positive effect. It is believed that this is due to prevention of overoxidation (overdoping).

Organic metals. Introduction of indium and thallium tetrachloride anions into polyacetylene by anodic oxidation

Polyacetylene films can by oxidized electrochemically in LiCI–MCI3–nitromethane solutions (where M In and Tl) to give highly conducting polymers.

Composites Of Conducting Polymers: Polyacetylene - Polypyrrole

Abstract Pyrrole can be electrochemically polymerised onto polyacetylene anodes. The morphology of the resulting conducting composites depends on the initial doping state (e.g. conductivity) of the polyacetylene. The air and water stability of the conducting composites is excellent compared to doped polyacetylene. Both components conduct the current.

Study On The Electrochemical Doping Of Polyacetylene With Selected Metal Halides

Abstract Electrochemical oxidation has been found to be a convenient method for introduction of tetrachloride anions of Fe, Al, In, T1 into polyacetylene. EPR, Mossbauer spectroscopies and elemental analyses show that oxidation (doping) and reduction (undoping) cycle in (CH)X - L1Cl/MCl3 systems is not totally reversible - and is accompanied by irreversible side reactions which limit possible application of (CH)X - metal chloride systems in energy storage devices.

The influence of water on the degradation of FeCl3-doped polyacetylene

The degradation rate of FeCl3-doped polyacetylene in air and argon is dependent on the water content of the gas phase.