Conductivity, polarization and electrorheological activity of polyaniline nanotubes during thermo-oxidative treatment

A facile thermal oxidation method in air is suggested to treat chemically synthesized conducting polyaniline (PANI) nanotubes in order controllably to decrease the conductivity. The structure, morphology and conductivity were characterized, and the polarization and electrorheological (ER) properties of nanotubes when dispersed in insulating oil were measured as a function of the thermal-oxidative time. Results showed that the appropriate thermal oxidation treatment did not destroy the nanotube morphology but induced the deprotonation and oxidation of PANI backbone. As a result, the conductivity was decreased and the polarization properties were changed. The nanotubes obtained after thermal oxidation at 200 °C for 4 h demonstrated the optimal ER performances. The ER activity decreased as the thermal oxidation time increased, and this could be explained by the change of polarization properties.