The relationships between surface and electrical properties of CSA doped PANI films

Comprehensive surface free energy (SFE) analysis and surface-electrical property relationships of de-doped and camphorsulfonic acid (CSA) doped polyaniline (PANI) films were not handled systematically previously. In this work, changes of surface and electrical properties of CSA doped PANI films were evaluated simultaneously with respect to dopant concentration. For this purpose, PANI was synthesized and subjected to secondary doping process by using various amounts of CSA in m-cresol medium. Following this, detailed SFE analysis of both de-doped and CSA doped PANI films was performed by evaluating the wettability characteristics of these films through contact angle measurements. The Lifshitz-van der Waals (LW) and polar (acidic, basic) components of SFE were calculated by using acid-base (AB) and geometric mean (GM) approaches. The results suggest that while the polar components and total SFE tend to be ever increasing with CSA concentration, the conductivity reaches a maximum at 55 wt% CSA. Also, the rate of increase of the acidic component of SFE was limited when conductivity is increasing. However, when conductivity tends to decrease, such rate was found to be rapidly increasing. The underlying mechanism of this behavior was discussed along with FTIR, XRD, SEM, 3D profilometer, and contact angle hysteresis analysis.