Effect of reagent concentrations used to synthesize polypyrrole on the chemical characteristics and optical and electronic properties of the resulting polymer

Abstract

Our objectives were to correlate conditions used to synthesize polypyrrole with the chemical characteristics of the resulting polymer, and then to correlate these chemical characteristics with electronic and optical properties of the polymer. The polypyrrole samples were synthesized from aqueous solutions of Fe 3+ and pyrrole. Samples with differing chemical characteristics were obtained by varying the initial concentrations of Fe 3+ and pyrrole in the polymerization solutions. The initial concentration of Fe 3+ in all polymerization solutions was 50 times higher than the initial concentration of pyrrole in the solution. However, the initial concentrations of Fe 3+ and pyrrole varied from 2.0 M Fe 3+/0.04 M pyrrole to 0.06 M Fe 3+/0.0013 M pyrrole. This yielded polypyrrole samples having different chain and conjugation lengths and different concentrations of chemical defect sites. We show that both electronic and optical conductivity are affected by these changes in conjugation length and concentrations of chemical defects.