Electrochemical polymerization of dithienylethylene, ‐butadiene, and ‐hexatriene

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AbstractConductive poly[(2,2′‐bithiophene‐5,5′‐diyl)‐(1,3‐butadienylene)] (1b) and poly[(2,2′‐bithiophene‐5,5′‐diyl)‐(1,3,5‐hexatrienylene)] (1c) films were obtained from the electrochemical polymerization of the corresponding α,ω‐dithienylpolyenes in the presence of Bu4NClO4 as a supporting electrolyte. These polymers were identified by their IR spectra. The current efficiency was 72 and 82%. Electrochemical polymerization of 1,2‐bis(2‐thienyl)ethylene did not give a film but a powder as product. In the UV spectrum of poly(1b), oxidized with ClO4 as counterion, three bands are observed at 350, 455 and 1 000 nm (shoulder). The last two bands dissappear in the neutral film. ESCA indicates that the S2p peak in symmetrical in the neutral film, but the oxidized films show a shoulder on the higher binding energy side of the peak. The neutral film shows an asymmetrical ESR signal, whereas that of the oxidized one is symmetrical. In air the conductivity decreases to about 20% of the initial value in 70 days, but the neutral film is quite stable.