2-DIMENSIONAL GROWTH OF POLYPYRROLE WITH A FRACTAL PATTERN AND DEPENDENCE OF PATTERN ON POLYMERIZATION CONDITION

Polypyrrole with a fractal pattern has been prepared by electrochemica l polymerization method with the needle-circle electrode configuration in electrolyte solution of acetonitrile containing sodium p-toluenesu lfonate and monomer. Under certain polymerization conditions, the poly pyrrole has been polymerized not only on the needle but also on the bo ttom surface of the cell and has grown to the circle electrode with br anching. The growth patterns on the cell are classified into three typ es: broad leaf-like, DLA-like and needle-like patterns. The patterns d epend on the polymerization conditions such as applied voltage and con centrations of electrolyte and monomer. The patterns can be controlled by the polymerization conditions. A neural network pattern has been s ynthesized by changing the condition during the polymerization. The fr actal dimension of the pattern has been calculated from the self-corre lation function, which is obtained using a fast Fourier transform tech nique.