A NOVEL TYPE OF SEMICONDUCTING POLYMERS - SYNTHESIS AND PROPERTIES OF ELECTROCHEMICALLY-DOPED POLYMERS CONTAINING PENDANT OLIGOTHIOPHENES

For the purpose of developing a novel type of electrically conducting polymers, synthesis and properties of electrochemically-doped, non-conjugated vinyl type polymers containing oligothiophenes as pendant groups have been studied. New vinyl monomers, 2-[4-(2-thienyl)-phenyl]-5-vinylthiophene and 5-vinyl-2,2':5',2'':5'',2'''-quaterthiophene, have been synthesized, and electrolytic polymerization carried out by controlled potential anodic oxidation. The resulting polymers were identified as partially oxidized radical cation salts with ClO4- as a dopant, having partially cross-linked structures. The polymers undergo reversible color changes. Electrochemically-doped poly(5-vinyl-2,2':5',2'':5'',2'''-quaterthiophene) exhibits room-temperature conductivities of ca. 10(-7) S cm-1 with activation energies of ca. 0.5 eV.