Charge transport and EPR of PAN-AMSPA (DCA)

We present the charge transport and magnetic properties of polyaniline dope d with 2-acrylamido-2-methyl sulfonated propanoic acid (PAN-AMSPA) includin g temperature dependent de conductivity sigma(DC)(T), thermoelectric power S(T), and electroparamagnetic resonance (EPR). The temperature dependent re duced activation energy W(T) plot from sigma(DC)(T) with sigma(300K) simila r to 140 S/cm and sigma(10K)/sigma(300K) similar to 0.9 shows that PAN-AMSP A is in the metallic regime of the insulator-metal transition. The analysis of EPR (9.5GHz) Dysonian lineshape results in substantially larger sigma(M W) than sigma(DC). Results are discussed in terms of inhomogenous disordere d materials. U-shaped S(T) with S(300K) similar to +2.5 +/- 0.5 mu V/K can be explained in terms of an effective medium model in accord with the inhom ogeneous disorder present. For the stretched samples, the temperature depen dences of sigma(DC)(T) are stronger than that of unstretched sample with th e weak temperature dependent anisotropy, even though the parallel direction room temperature values are higher than that of unstretched sample. This i s consistent with expected effects from the inhomogeneous disorder.