SYNTHESIS OF FREESTANDING POLY(3,4-ETHYLENEDIOXYTHIOPHENE) CONDUCTINGPOLYMER-FILMS ON A PILOT-SCALE

Electrochemical polymerization of 3,4-ethylenedioxythiophene (EDT) was carried out in the presence of monomeric anions or polyanions in elec trolyte solutions. While no free-standing films of poly(3,4-ethylenedi oxythiophene) (PEDT) were obtained using monomeric anions as dopants, flexible conducting polymers were obtained using novel polyanions, e.g ., sulfated poly(beta-hydroxyethers) (S-PHE), sulfated poly(beta-hydro xyethers) having trifluoromethyl groups (S-PHEF), and sulfated polybut adiene (S-PBD). The conductivity of these PEDT/polyanion composites ex ceeded 150 S/cm, and reached as high as 400 S/cm when S-PHEF was used as dopant. These conducting composites demonstrated superior mechanica l properties, and PEDT/S-PBD showed an elongation of 78-110% at 100 de grees C. The electrical properties were strongly dependent on the synt hesis conditions. The important parameters were optimized for the S-PH E polyanion. By doing this the conductivity of the PEDT/S-PHE composit e reached values around 230 S/cm. Based on the optimized parameters, a continuous synthesis of PEDT/S-PHE composite was developed leading to reproducible conducting composites. The electrode is cylindrical and 10 cm wide. The computer-controlled system enabled the preparation of PEDT films more than 20 m long.