ELECTROCHEMISTRY OF CONDUCTIVE POLYMERS .14. IN-SITU SPECTROELECTROCHEMICAL AND KINETIC-STUDIES ON POLY(3-METHYLTHIOPHENE) GROWTH

The growth mechanism of poly(3-methylthiophene) has been studied employing in situ spectroelectrochemical and kinetic measurements. Results indicate that: (i) the polymer film grown only when 3-methylthiophene is oxidized, suggesting that the radical-radical coupling reaction is important for the polymer growth; (ii) concentration of intermediate species, i.e., radical cations of the trimer and tetramer, are maintained at a steady-state level during the growth; and (iii) both monomer and polymer concentrations appear in the rate expression, indicating that both the monomer and polymer participate in the polymer growth. The growth is not autocatalytic, and oxidation of both the monomer and oligomer or polymer is required for further growth of the polymer. The reaction order in the rate expression depends on experimental conditions ranging 0.5 is similar to 1 for the monomer, while it is about 0.5 for the polymer.