Polythiophenes electroactive

The use of electroactive polymers for overcharge protection has been recently reported for lithium-ion batteries.The electroactive polymer incorporated into a battery s separator is an attractive new option for overcharge protection. Thomas et al. developed a mathematical model to explain how electroactive polymers such as polythiophene can be used to provide overcharge protection for lithium-ion... 

In contrast, anodic oxidation of tetra-2-(/T-methylterthienyl)silane provides polythiophene without desilylation9. The polymer has a 3D electroactive jr-conjugated system (equation 5). 

In considering the potential applications of electroactive polymers, the question always arises as to their stability. The deterioration of a physical property such as conductivity can be easily measured, but the chemical processes underlying it are not as easy to be revealed. In order to understand them, XPS has been used to follow the structural changes which occur in the polymer chain and the counter-ions of the doped polymer. The following sections present some XPS findings on the degradation of electroactive polymers, such as polyacetylene, polypyrrole, polythiophene and polyaniline, in the undoped and doped states. 

Intercalation of electroactive polymers such as polyaniline and polypyrrole in mica-type layered silicates leads to metal-insulator nanocomposites. The conductivity of these nanocomposites in the form of films is highly anisotropic, with the in-plane conductivity 10 to 10 times higher than the conductivity in the direction perpendicular to the film. Conductive polymer/oxide bronze nanocomposites have been prepared by intercalating polythiophene in V2O5 layered phase, which is analogous to clays. °° Studies of these composites are expected not only to provide a fundamental understanding of the conduction mechanism in the polymers, but also to lead to diverse electrical and optical properties. 

PAn is now accepted to have the general polymeric structure shown as 1. It differs from most other conducting electroactive polymers, such as polypyrroles (PPy s Chapters 2 and 3) and polythiophenes (Chapter 6), in that it possesses three readily accessible oxidation states. These range from the fully reduced (y = 1) leucoemeraldine state to the half-oxidized (y = 0.5) emeraldine form to the fully oxidized (y = 0) pernigraniline state. The ES form 2 is the state with the highest conductivity. 

Polythiophenes (PTh s) (1 shown subsequently) have much in common with polypyrroles. They are formed from a cyclepenta-diene molecule, but which has an S heteroatom. Thiophene is oxidized to form a conducting electroactive polymer (CEP), with the greatest conductivity obtained from a-a linkages. There are some important differences between polythiophenes and polypyrroles, and these are discussed here. 

Recently novel polyelectrolytes 8 have been incorporated into polythiophene structures and found to generate a mechanically strong electroactive deposit.16... 

Le Floch and co-workers isolated ferrocene-containing polythiophenes for use in deoxyribonucleic acid (DNA) detection.230 The reaction between thiophene 160 and the functionalized ferrocene 161 gave the ferrocene functionalized polythiophene in a quantitative yield (Scheme 2.43). Polymerization in the presence of FeCl3 led to a water-soluble polymer containing a cationic side chain and an electroactive ferrocene moeity. These polymers showed a DNA detection limit of 5 X10-10M. 

The polythiophenes arc by far the most commonly studied S-containing electroactive polymers. There is limited work carried out with PPS. XPS was used to investigate the extent and nature of the oxidation of PPS powder under slurry conditions, either in toluene at 60°C with a mixture of formic acid and hydrogen peroxide as the oxidizing agent or methylene chloride at 25°C with 3-chlorobenzoic acid [357], In the surface region, up to 75% of sulphide (—S—) sulphur is oxidized to sulphoxide (—(S=0)—) and... 

A polythiophene anode in an aqueous electrolytic system, showed irreversible changes at a potential beyond 0.9 V on repeated reduction, suggesting that the breakdown into lower oligomers occurs, as evident from its Raman spectra [268]. However, the loss of electroactivity, electrical conductivity, electrochromic properties, mechanical properties, compact morphology... 

Huchet, L., S. Akoudad, and J. Roncali. 1998. Electrosynthesis of highly electroactive tetrathiaful-valene-derivatized polythiophenes. Adv Mater 10 (7) 541-545. 

Reddinger, J.L., and J.R. Reynolds. 1998. Site specific electropolymerization to form transistion-metal-containing, electroactive polythiophenes. Chem Mater 10 1236-1243. 

Berridge, R., PJ. Skabara, C. Pozo-Gonzalo, A. Kanibolotsky, J. Lohr, W. McDouall, E.J.L. Mclnnes, J. Wolowska, C. Winder, N.S. Sariciftci, R.W. Harrington, and W. Clegg. 2006. Incorporation of fused tetrathiafulvalenes (TTFs) into polythiophene architectures Varying the electroactive dominance of the TTF species in hybrid systems. / Phys Chem B 110 3140-3152. 

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