DIFFUSION BEHAVIOR OF ANIONS IN POLYANILINE DURING ELECTROCHEMICAL UNDOPING .2. EFFECT OF THE PREPARATION CONDITIONS OF POLYANILINE ON THE DIFFUSION-COEFFICIENT OF BF4-

The diffusion coefficients of BF4- ion during the undoping process in polyanilines prepared at various electropolymerization current densities were measured by the potential step method, assuming the cylindrical diffusion system. All polyanilines prepared at various current densities in HBF4 aqueous solution have a fibrous structure, but their diameters were different. From the result of the potential step experiment, it can be seen that the diffusion coefficients in these polyanilines during the undoping process increased with increasing diameter of polyaniline. On the other hand, from Fourier transformed infrared spectra, it can be seen that they have very similar chemical bond characteristics. However, from the X-ray diffraction patterns, it can be expected that the crystallinity of polyaniline increases with decreasing diameter of polyaniline. These results indicate that the diffusion coefficient of BF4- ion in polyanilines during the undoping process strongly depends on the arrangement of the molecular chains in the polyaniline fibril which is easily changed by the preparation conditions, even though they have a similar morphology.