1999 Volume 67 Issue 1 Pages 45-50
Conducting polymers based on polyanilines with highly soluble and yet sustain relatively high conductivity were attempted to synthesize by either electrochemical or chemical oxidation from the solutions containing aniline monomers and traces of para-substituted anilines, namely p-toluidine or sulfanilic acid. The resulting polymers turned out to have low molecular weight electroactive polyanilines terminated by them in the polymerization process. The as-grown polymers which are at the doped state, show high solubility (250mg m1−1) in N-methylpyrrolidinone, while ordinary polyanilines particularly at the doped state scarcely soluble in NMP or any other solvents. Gel permeation chromatography indicated that the number average molecular weight of such polymers were obtained as 4,500 to 6,100 (vs. polystyrene standards) which should be the lowest among the relevant data so far reported. The conductivity of these polymers were found unexptedly high（10−1 to 10−3 S cm−1） for other soluble polyanilines substituted with various functional groups（normally 10−5 to 10−7S cm−1). By casting these polymers from the NMP solutions at concentrations of max. 250mg m1−1, the thin and uniform polymer films (typically 0.1mm in thickness) were successfully formed on an anodized A1(Al2O3) foil to device Al electrolytic capacitors for further testing. The Al electrolytic capacitor displayed good/fair impedance-frequency characteristics in that they have relatively high resonance frequencies（in the order of 107Hz） and showed low equivalent series resistance (min. 1. 4Ω).