Electromagnetic absorption of polyanilines at microwave frequencies

Abstract

Chemically synthesized emeraldine base polymer was treated with HCl to yield different levels of protonation corresponding to σ dc values ranging from 10 −7 to 10 2 S/m. For different σ dc values, broad-band absorption of electromagnetic waves was measured in the range 1 MHz–20 GHz at room temperature. A quasi linear relationship was observed between log σ and log ω above 100 MHz, confirming the power law σ = ω s (0 < s < 1). For the most conductive samples ( σ dc ⋍ 10 2 S/m, s = 0 ) corresponding to highly protonated polymers, the conductivity was shown to be constant and independent of frequency. With d.c. conductivities lower than 10 −1 S/m, s increased from zero to unity.