CHAIN-LENGTH EFFECT ON THE ELECTROACTIVITY OF POLY(N-ALKYL-3,6-CARBAZOLEDIYL) THIN-FILMS

Several poly(N-alkyl-3,6-carbazolediyl)s (PCZS) have been obtained by electroreduction of the corresponding dibromomonomers in the presence of a catalytic Ni(0)-based system. Depending on the nature of the alkyl group linked to the nitrogen atom, PCZS are soluble in organic solvents such as nitrobenzene, chloroform and tetrahydrofuran and insoluble in acetonitrile and alcohols. Taking these properties into account thin films have been prepared (in the neutral state) either by casting from solutions or directly by electrodeposition onto conducting substrates in the CH3CN/NBu4BF4 medium. Electrochemical behavior of these materials in the range 0-1.4 V versus saturated calomel electrode (SCE) is strongly dependent on the macromolecular chain length, but is slightly affected by the nature of the alkyl chain. Depending on the potential applied, the films are either colorless, green or blue. The redox processes involved in electrochemical oxidation of the polymer as well as those of the oligomers are discussed. © 1990.