ELECTROSYNTHESIS OF POLYPYRROLE IN IODIDE SOLUTION - FILM GROWTH, REDOX BEHAVIOR AND POTENTIOMETRIC RESPONSE

Electrosynthesis of polypyrrole (PPy) was studied in aqueous lithium i odide solution. The electrochemical polymerization showed features of two-dimensional growth and the reaction was catalyzed by the I-2/I- co uple. The potentiometric response of PPy doped with iodide (PPy(I)) wa s studied both in iodide solutions and solutions containing the redox couple I-2/I- with a fixed concentration ratio 0.4 but varying the ini tial concentration of iodide in the range 10(-5)-1.0 M. Linear, anioni c response was observed in the concentration range 10(-1)-10(-3) M whe n only iodide species was present. However, contribution of the redox response to the overall potentiometric response increased with increas ing concentration of I-2 although the concentration ration between iod ine/iodide was kept constant. The influence of phosphate buffer on the electroactivity of PPy doped with iodide was also studied. (C) 1997 E lsevier Science B.V.