G. Zotti et al., New highly conjugated polycationic polythiophenes from anodic coupling of (4H-cyclopentadithien-4-yl)alkylammonium salts, MACROMOLEC, 34(12), 2001, pp. 3889-3895
Anodic coupling of some (4H-cyclopentadithien-4-yl)alkylammonium perchlorat
es in acetonitrile + 0.1 M Bu4NClO4 produces polycationic polythiophene fil
ms with high conjugation length (lambda (max) = 590-600 nm; E degrees = -0.
3 V vs Ag/Ag+), conductivity (0.5-2 S cm(-1)), and solubility in organic so
lvents such as ethanol and acetonitrile. The 4-hexyl-substituted polymer is
reversibly reduced (n-doped) at E degrees = -2.08 V. Electrochemical quart
z crystal microbalance measurements of the ion flux during n-doping in acet
onitrile have shown that anion ejection is dominant over cation injection,
attaining 90-95% of the total ion flux. The kinetics of the n-doping proces
s has been investigated by cyclic voltammetry in comparison with that of th
e analogous 4,4 ' -dihexyl-substituted polymer. In the latter cation inject
ion is slower and shows a strong dependence on the cation size.