Aqueous reactivity of polyacetylene: PH Dependence

The stability of iodine-doped polyacetylene in aqueous environments and the particular effect of variations in pH upon the stability of the intrinsically conducting polymer has been investigated in a variety of aqueous environments. Stability performance was established by simultaneously monitoring the four-probe electrical conductivity and the steady-state electrode rest potential during exposure of the metallically doped, [CHI_0.18-0.20]_x. polymer over an approximate 10-day period. Initial polymer conductivities were in all cases between 100 and 300 S cm^-1. The initially measured electrode potential was in all cases ca. 0.45 V vs SCE irrespective of the doping levels studied; y = 0.007, 0.168, 0.210 or the pH of the test solution in the range 1-9. The rate and extent of degradation in these material properties was found to increase at the extremes of pH. Alkaline conditions were found to be generally more aggressive to the p-doped polymer compared to acidic conditions. The normally slow but ever present degradation of iodine-doped polyacetylene which occurs even under inert atmosphere conditions is accelerated in all aqueous environments leading to an often precipitous degradation of electrically based material properties.