Mixed‐surfactant‐induced morphology change of polyaniline

In this study, polyaniline (PANI) was synthesized in the presence of a mixture of two surfactants, dodecylbenzene sulfonic acid (DBSA) and sodium dodecyl sulfate (SDS). The morphology of PANI observed under transmission electron microscopy was found to be spherical and cylindrical shapes. At low DBSA concentrations (2 and 10 mM), the addition of SDS made it easier to obtain the cylindrical morphology of PANI. A scheme based on the deformation and coagulation of mixed micelles was proposed to explain the morphological change of PANI. In the system of 10 mM DBSA, when the SDS concentration was 2 mM, the tubular morphology of PANI was observed, whereas when the SDS concentration was increased, a fiber morphology of PANI was found. The relative ratio of anilinium cations to free aniline played a key role in whether the tube or fiber morphology existed. Finally, a significant improvement in the conductivity of PANI was achieved when PANI had a cylindrical morphology.