ON THE SELF-DOPING OF POLY[N-(3'-THIENYL)ALKANESULFONIC ACID] AND POLY[(3-CARBOXYALKYL)THIOPHENE]

Poly[n-(3'-thienyl)alkanesulfonic acid] is already self-doped without applying any electric potential. Such doping is different from that in troduced by electrochemical doping of this PolYmer acid or its salt, a nd is termed 'self-acid-doping' in this work. Its structure is propose d to be composed of four basic units: an undissociated unit, a ring wi th an electron/hole pair and -(CH2)nSO3- side chain, a ring with a hol e and addition of proton from a side chain on the a-carbon, and a bipo laron structure, as determined by studying the simulated system: polyt hiophene doped with sulfuric acid. Poly[(3-carboxyalkyl)thiophene] can not be self-acid-doped or self-doped, as evidenced by the facts that ( i) poly(3-octylthiophene) (P3OT) cannot be electrochemically doped wit h alkylcarboxylate or arylcarboxylate as counter-anion, and (ii) P3OT cannot be chemically doped with alkylcarboxylic or arylcarboxylic acid s.