Effect of annealing on electrical conductivity and morphology of polyaniline films

We report structure-property relationships of polyaniline emeraldine base ( EB) films that were produced by combining different processing steps in var ious sequences. The effect of annealing and doping processes on the surface structure of the films was investigated by atomic force microscopy (AFM), and the corresponding changes to the chemical structure of the EB films wer e monitored by Fourier transform infrared spectroscopy. AFM results indicat e that after doping polyaniline (EB) films with HCl, the root mean square ( rms) roughness of the surface of EB film increased similar to 46%. When the doped films were annealed at 180 degreesC under a nitrogen atmosphere for 3 h, the rms roughness was essentially unchanged from that of the initial, undoped films. The electrical conductivity of the films also showed a signi ficant dependence on the processing sequence. When the doped polyaniline (E B) films were annealed, no electrical conductivity was observed. When these films were redoped, only similar to6% of the initial conductivity could be recovered. In another processing sequence in which the polyaniline (EB) fi lms were first annealed and then doped, the electrical conductivity was onl y similar to 12% relative to the film that was doped immediately after bein g cast. From this work, a strategy to reduce the surface roughness of films made from electrically conducting polyaniline (EB) is proposed. (C) 2001 J ohn Wiley & Sons, Inc.