Magnetic properties of undoped and doped poly[(3-methoxy)4,6-toluene] (P3mt)

The magnetic properties of two types of poly[(3-methoxy)4,6-toluene] (P3mt1 and P3mt2) are studied before and after doping with iodine or organic acids (CF3COOH or CH3SO3H) in a range of temperature varying from 110 to 460 K. Under 250 K and independent of the state, the magnetic susceptibility χ obeys Curie law dependence. Up to this temperature, χ is governed by a Pauli law contribution. This fact can be related to localized or delocalized spin. Furthermore, iodine doping induces distortion in the polymers that affects the ESR line distribution. In the case of organic acids doping process, a hyperfine structure with hyperfine coupling constant values between 2.2 and 2.8 G is observed. As the spin concentration decreases, we deduce that in the case of P3mt2, there is a de-doping process.