Evidence for different equilibrium regimes in poly(phenylacetylene)-iodine solutions by means of low-frequency electrical conductivity measurements

The electrical conductivity of poly( phenylacetylene)-iodine in tetrahydrofuran solutions has been measured at the frequency of 10 kHz, at different polymer concentrations in the presence of different amounts of iodine up to a concentration of 20 mg ml(-1). The data have been analysed in the light of current theories of polyelectrolyte solutions, considering the effect of counterions along the charged polymer chain. The dependence of the electrical conductivity on the iodine concentration suggests that the conduction mechanism is governed by different equilibria, resulting in two different charge-transfer complexes, PPA(+)I(5)(-) and PPA(+)I(3)(-); both of them can give rise to ion fluctuation