Magnetic properties of conducting polyanilines induced by organic acids and solvents

Characteristic paramagnetism induced by organic acids and solvents was obse rved for conducting polyanilines. Most of spins in this material ate locali zed below 100 K therefore the Curie spin contribution became large. Above 1 00 K, however, the polyaniline showed metallic features that is most spins- are delocalized. Pauli susceptibility and total density of state at the Fer mi level were determined as similar to 5 x 10(-5) emu/mol and 1-2 state/eV in 2-ring unit, respectively. Curie spin concentration reaches a maximum ar ound 50 K. The effect of solvent on these magnetic properties need to be em phasized for the cases of emeraldine base (EB)-camphosulfonic acid (CSA) an d dodecylbenzenesulfonic acid (DBSA)/acetic acid. This solvent can form the localized small spin-domains, in which all the spins align parallel to eac h other at low temperature. The formation of spin-domains increases the net magnetic dipole and finally enlarges the magnetic susceptibility.