Study of the sorption phenomenon accompanying the break-in process of polymer film electrodes using a quartz crystal microbalance

Abstract

The sorption of solvent molecules and ions into poly(tetracyanoquinodimethane) surface films during the break-in process has been studied under potentiostatic steady-state and potential cycling conditions using the electrochemical quartz crystal microbalance technique. No sorption of solvent molecules and ions was found in the case of unelectrolysed virgin films. It has been shown that the mass change of the film follows the charge and discharge processes occurring in the films; however, a gradual decrease of the frequency values corresponding to the starting potential can be observed which can be considered as a measure of the electrolyte content in the discharged film layer. No equilibrium with regard to the electrolyte was attained during the potential cycling even at slow sweep rates. The time necessary for break-in, i.e. for the swelling and wetting of the polymer structure to be completed, increases with the film thickness and electrolyte concentration.