CHARGE AND ION-TRANSPORT IN POLY(PYRROLE COPPER PHTHALOCYANINE TETRASULFONATE) DURING REDOX SWITCHING

The redox switching properties of electrochemically synthesized poly(pyrrole copper phthalocyanine-3,4'4 '',4''-tetra-sulfonate) (PP-CuPTS) have been investigated in aqueous electrolytes utilizing the electrochemical quartz crystal microbalance (EQCM) technique. Ion transport during redox switching is found to be cation dominant, indicating that the copper phthalocyanine complex is physically entrapped in the polymer film and is confirmed by the fact that no CuPTS is seen in the switching electrolyte. Coulometric and gravimetric analyses show that the redox switching rate of PP-CuPTS is related to cation mobility and is a function of ion hydration. Correlation of the charge and mass changes of the polymer during switching reveals that there exists two distinct regimes. An initial mass flux dominant region is followed by a considerable amount of charge flux which is accompanied by no net mass flux. These are likely to be due to ion hydration and simultaneous solvent or co-ion flux in the opposite direction of the mobile ionic species, respectively.