Enhanced pH stability of conducting polyaniline by reprotonation with perfluorooctanesulfonic acid

Electrically conducting polyaniline (PANI) films have been prepared by reprotonation of the emeraldine base form of PANI with perfluorooctanesulfonic acid (PFOS). The reprotonated PANI-PFOS films have been characterized by UV–vis spectroscopy, water contact angle and electrical conductivity measurements. We report that reprotonation of PANI base with PFOS increased the water contact angle from 25° to 105°. The hydrophobic PANI-PFOS maintained a good level of conductivity even at pH = 8 (σ = 1.0 × 10−2 S cm−1) whereas the PANI hydrochloride lost its conductivity at this pH (σ = 5.0 × 10−9 S cm−1). Long-term stability tests showed that the reprotonated PANI-PFOS film remained in its conducting form for three month.