Investigation of some physicochemical properties of camphor sulfonic acid (CSA)-doped poly(o-anisidine) (PoAN) and CSA-doped PoAN/ABS composites

Camphor sulfonic acid (CSA)–doped poly(o-anisidine) (PoAN) has been found to possess the electrical conductivity of 10 S/cm. This value is rather low compared to that of (≈200 S/cm) CSA-doped polyaniline, which may arise from a limited transformation of coil-like conformation to an expanded one. Viscosity data and optical absorption spectra provided strong evidence for the existence of coil-like CSA-doped PoAN chains in m-cresol. The shift of IR bands of benzenoid and quinoid rings toward a lower wave number and the appearance of the bands at ≈1600 and 1173 cm−1 (the IR is inactive but becomes active on doping) suggested the protonation of CSA-doped PoAN. The thermogravimetric profile of CSA-doped PoAN showed a five-step decomposition pattern with the thermal stability up to 134 °C. The mass spectra taken simultaneously with the thermogram revealed that dopant CSA is completely eliminated around 360 °C, but the breakdown of polymer chains does not occur very briskly at this temperature. Composites of CSA-doped PoAN with insulating acrylonitrile–butadiene–styrene copolymer (ABS) were fabricated, and it was found that the composites showed a percolation behavior in which the electrical conductivity rose sharply at about 4 weight % of CSA-doped PoAN in the ABS composite. The STM data demonstrated the formation of a continuous path at the percolation threshold. The Poole–Frenkel effect was observed for the conduction scheme in the CSA-doped PoAN/ABS composite.