Charge Transport and EPR of PAN-AMSPA (DCA)

We present the charge transport and magnetic properties of polyaniline doped with 2-acrylamido-2-methyl sulfonated propanoic acid (PAN-AMSPA) including temperature dependent dc conductivity σDC(t), thermoelectric power S(T), and electroparamagnetic resonance (EPR). The temperature dependent reduced activation energy W(T) plot from σDC(T) with σ(300K) ~ 140 S/cm and a(10K)/σ(300K) ~ 0.9 shows that PAN-AMSPA is in the metallic regime of the insulator-metal transition. The analysis of EPR (9.5GHz) Dysonian lineshape results in substantially larger σMW than σDC. Results are discussed in terms of inhomogenous disordered materials. U-shaped S(T) with S(300K) ~ + 2.5 ± 0.5 μV/K can be explained in terms of an effective medium model in accord with the inhomogeneous disorder present. For the stretched samples, the temperature dependences of σDC(t) are stronger than that of unstretched sample with the weak temperature dependent anisotropy, even though the parallel direction room temperature values are higher than that of unstretched sample. This is consistent with expected effects from the inhomogeneous disorder.