Electron paramagnetic resonance and conductivity studies on Poly (m-toluidine) salts and their bases

Five different poly(m-toluidine) (PMT) salts were synthesized chemically using different protonic acids and their bases were obtained by dedoping the salts using aqueous $NH_4OH$. The electron paramagnetic resonance (EPR) spectra of PMT salts and their.bases were recorded at different temperatures. The results show a thermally activated dependence for PMT-HCI and a Curie-Weiss behaviour in the range 40 to 200 °C for the other salts. The EPR signal intensities of the PMT bases are temperature-independent except for PMT dedoped from $CH_3COOH$ which shows thermally activated paramagnetism. Ambient-temperature electrical conductivities were obtained by the two-probe method for PMT salts and bases. The results are consistent with polaron spins that are antiferromagnetically coupled. The migration of paramagnetic polarons along the polymer chain alone is not responsible for the charge transport. The effect of substituents on polyaniline is discussed