ELECTROMAGNETIC ABSORPTION OF POLYANILINES AT MICROWAVE-FREQUENCIES

Chemically synthesized emeraldine base polymer was treated with HCI to yield different levels of protonation corresponding to ad, values ranging from 10(-7) to 10(2) S/m. For different sigma(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 sigma and log omega above 100 MHz, confirming the power law sigma = omega(s) (0 < s < 1). For the most conductive samples (sigma(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.