Proton modification of conducting polypyrrole

Experimental resluts on the protonic modification of the conducting polymer polypyrrole are reported. It is shown that the conductivity of the electrochemically generated polymer decreases over four orders of magnitude on treatment with strong alkalies. The effect is reversed upon treatment with proton acids. This process has been studied through electrical conductivity, optical absorption and XPS results. The observations indicate that the NH bond in the pyrrole units is disrupted in alkaline solution, leading to deprotonation. This effect is reversed in acid solution, where the protons are attached again. The deprotonation leads to shorter conjugated segments on the polymeric backbone and increasing hopping lengths, decreasing the conductivity.