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 densiti es were measured by the potential step method, assuming the cylindrica l diffusion system. All polyanilines prepared at various current densi ties in HBF4 aqueous solution have a fibrous structure, but their diam eters 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 pol yaniline. On the other hand, from Fourier transformed infrared spectra , it can be seen that they have very similar chemical bond characteris tics. However, from the X-ray diffraction patterns, it can be expected that the crystallinity of polyaniline increases with decreasing diame ter of polyaniline. These results indicate that the diffusion coeffici ent of BF4- ion in polyanilines during the undoping process strongly d epends on the arrangement of the molecular chains in the polyaniline f ibril which is easily changed by the preparation conditions, even thou gh they have a similar morphology.