The effect of glutaraldehyde on the electrochemical behavior of polyaniline

Polyaniline was exposed to glutaraldehyde under different experimental cond itions and in all cases reduction of the polymer was observed. The reductio n of polyaniline by glutaraldehyde in non-electrolytic, aqueous medium unde r reflux, caused the polymer to become completely undoped and with high imp ermeability to anions as evidenced by the displacement of the first anodic voltammetric wave of polyaniline in acidic medium and by its dependence on the kind of acid employed. The permeability and the normal electrochemical behavior of the polymer could be restored after the first voltammetric cycl e. Under simple exposure to glutaraldehyde in buffered solution (pH 8) the reduction is not so extensive and changes in voltammetric behavior from cyc le to cycle are related to the high pH of the medium. Some glutaraldehyde p olymerizes inside the polyaniline matrix, causing the first voltammetric wa ve of polyaniline to be slightly displaced to more anodic potentials. Enzym e immobilization on polyaniline with glutaraldehyde seems to be related to this polyglutaraldehyde produced in buffered solutions. (C) 1999 Elsevier S cience Ltd. All rights reserved.