Preparation and characterization of flexible polypyrrole nitrate films

The electrochemical synthesis of polypyrrole (PPy) was studied in 1,2-propanediol carbonate (PC) solution containing various kinds of nitrate salts. Strong dependence of the tensile strength of the as-prepared polypyrrole nitrate (PPy(NO3−)) films on the solvents, salts and polymerization temperature was observed. The mechanical strength of PPy(NO3−) increased with decrease of polymerization temperature. Flexible PPy(NO3−) films with tensile strengths as high as 107.7 MPa were obtained from 0.1 M pyrrole, 0.1 M Cu(NO3)2 · 3H2O and 0.2 M LiNO3 PC solution at the polymerization temperature of −20 °C. The tensile strength value is stronger than those of PPy films reported in the literature to date. Two kinds of surface morphologies of the PPy(NO3−) films prepared in PC solution were observed on a scanning electron microscopy (SEM) photograph.