Electrocatalytic thin films based on nordihydroguaiaretic acid-functionalyzed polyaniline

A novel composite, polymeric material can be obtained by potential cycling of polyaniline (PANI)-modified electrode in the presence of nordihydroguaiaretic acid (NDGA). As a consequence, the properties of PANI change from those of a conducting polymer to those of a redox polymer. Thus formed composite PANI-NDGA films show redox activity characterized by two new electrochemical couples observed at mid-peak potentials of 0.32 and 0.52 V (vs. Ag/AgCl, 0.5 M H2SO4). The peak currents exhibit a linear dependence on the potential scan rate as expected for surface-confined redox species and the peak potentials shift toward lower potentials with increasing solution pH at a rate of ca. 60 mV/pH unit. The PANI-NDGA composite film was found to electrocatalyze the reduction of iodate in acidic (pH 1.8) Britton-Robinson buffer. The modified electrode could be applied as an amperometric sensor for iodate. A linear dependence between the reduction current and iodate concentration was observed over the range of 1-100 μM with a detection limit of 0.05 μM. The observed restructuring of PANI in the presence of NDGA was confirmed by AFM imaging and FT-IR spectroscopy.