Electrochemical and chemical polymerization of indole

Summary form only given. Electrochemical oxidation of indole, C/sub 8/NH/sub 7/, in non aqueous media like solutions of LiC1O/sub 4/ or LiBF/sub 4/ dissolved in acetonitrile, leads to the formation of polyindole, an air stable conducting polymer which exhibits interesting electrochromic properties. The green (doped state) to yellow (reduced state) colour change of the polymer can be observed over more than 450 000 redox cycles. From elemental analysis, it appears that the maximum monomer unit to counterion ratio is in the range 3-3.5. The RT electrical conductivity of pressed pellets of doped polyindole is close to 10-sup -1/ S.cm/sub -1/. Polyindole can be also obtained after chemical oxidation and subsequent polymerization of indole in appropriate media. The influence of the experimental sunthesis conditions on the morphology and the properties of the polymer is also discussed.