ELECTROCHEMICAL GROWTH OF POLY(3-DODECYLTHIOPHENE) AND ITS INTERPRETATION AS A FRACTAL

Poly(3-dodecylthiophene) with a fractal pattern has been prepared by an electrochemical method on the surface of a solution. The fractal dimension has been calculated by four methods. At an applied voltage of about 10 V, the fractal dimension indicates a maximum value of 1.79. The growth rate in the radial direction has a maximum value at about 7.5 V and the conductivity in the iodine doped state is a maximum for the sample prepared at a voltage of about 15 V in accordance with the voltage dependence of fractal dimension. Although the conducting polymer is usually doped by the counter-ion, BF4 -, in polymerisation an undoped region has been observed in the branches of the conducting polymer at high voltage. The time dependence of the fractal dimension has been calculated and the rise time has been found to depend on the applied voltage. By short circuiting the electrode after the polymerisation, the undoped region in the branch has proceeded concentrically from the tip of the growth to the needle electrode.