PROPERTIES OF ION-EXCHANGE MEMBRANES COMBINED WITH CONDUCTING POLYMERS ANISOTROPICALLY .1. EMF GENERATION BY REDOX REACTIONS ACROSS COMPOSITE MEMBRANE

In order to produce a new functional material composed of a cation exchange membrane and conducting polymers, pyrrole or aniline was polymerized in the cation exchange membrane phase anisotropically by chemical polymerization. When one side of the cation exchange membrane of ferric ion form was contacted with an aqueous pyrrole solution for a suitable period, a bilayer membrane, composed of a cation exchange membrane layer and a polypyrrole-impregnated-cation exchange membrane layer, was obtained. This is because a thin and tight layer is formed on the membrane surface which pyrrole molecules cannot permeate easily. This bilayer membrane produced emf which was dependent on relative humidity when the composite membrane was held tightly between two platinum plates. The observed maximum emf was 217 mV with a 2 M-OMEGA load. Analysis of ferric and ferrous ions in a polypyrrole-impregnated-cation exchange membrane showed that the membrane contained ferrous ions more than 98% to total iron ions. Thus, the emf of the composite membrane results from Fe2+-Fe3+ redox cell.