SELECTIVE POTENTIAL RESPONSE OF A POLY(N,N-DIMETHYLANILINE) POLY(ORTHO-CHLOROANILINE) DUAL-LAYER COATED ELECTRODE TO DISSOLVED IODIDE-IONS

Poly(N,N-dimethylaniline) (PDA) was easily obtained by an anodic oxidation of N,N-dimethylaniline in acidic media. PDA is a semiconductor having positively charged sites as quaternary ammonium groups in its polymeric backbone. It was possible for a PDA-film coated electrode to incorporate I- electrostatically; I- in the film was then oxidized electrochemically. Further, the oxidized products of I- still remained in the film. Although the electrode responded to dissolved I- potentiometrically, the response was disturbed by the presence of other redox species. On the other hand, poly(omicron-chloroaniline) (PCA) was also easily prepared by the electro-oxidation of omicron-chloroaniline in acidic solutions. On a PCA-film coated electrode, only the redox wave of I2/I- was observed, though PCA, itself, was electroinactive. In other words, the PCA film responded to I- selectively. The dual-layer (a PDA film incorporated oxidized products of I- and PCA film) showed a selective Nernstian response to dissolved I-.