Template-free enzymatic synthesis of electrically conducting polyaniline using soybean peroxidase

Synthesis of polyaniline (PANI) catalyzed by soybean peroxidase at 1 °C in either aqueous or partially organic media, was studied as a function of pH and reaction media. Kinetic studies indicated that, unlike chemical polymerization, enzymatic polymerization of aniline showed neither induction period nor auto acceleration. The redox reversibility and chemical structure of the synthesized PANI was strongly dependent on the starting pH of the reaction medium. UV–vis, FT-IR, WAXD and TGA analysis are used to explain how the enzymatic reaction conditions influence both the chemical structure and physical properties of the PANI. Optimal reaction conditions are outlined for the direct enzymatic synthesis of electrically conductive emeraldine salt with yield as high as 71%.