Novel approach to the synthesis of polyaniline possessing electroactivity at neutral pH

Abstract

A new approach is proposed for the synthesis of polyaniline via electrochemical polymerization of aniline at a very low concentration on a modified electrode surface. The electrode was modified with a sulfonated polyaniline, poly(2-methoxy aniline-5-sulfonic acid) (PMAS), which acted as an electroactive conductive template for the aniline monomer. The electrode surface was modified with PMAS via a number of different methods including cyclic voltammetric and potentiostatic deposition as well as dip and drop casting water-soluble PMAS onto the electrode surface. Electrochemical polymerization of aniline was then carried out at the surface of the modified electrode. Effect of different variables such as PMAS concentration, volume and pretreatment of the modified electrode on the polymerization of aniline was studied. The polymer synthesized at the PMAS modified electrode was characterized by electrochemical and UV–vis spectrophotometic techniques. Electrochemical studies showed that even at very low concentration of aniline (5.0 mM), an adherent, uniform and stable polyaniline film was deposited on the electrode surface. Without any further treatment, this polyaniline layer was found to be electroactive at a neutral pH which is crucial for biosensing applications.