Dependence of effective diffusion coefficients of PPy film on preparation process

Abstract

Conjugated polymers are promising materials for the use as soft actuators or as electrodes in batteries and the actuation mechanism of such polymers highly depends on the diffusion of counter ions into these polymers during the redox process. Among several conjugated polymers, polypyrrole doped with large immobile dodecylbenzene sulfonate anions (PPy/DBS) operating in aqueous electrolytes has been identified as one of the successful systems suitable for the use as artificial muscles. The insertion and expulsion of counter ions into PPy/DBS films when operating in aqueous electrolytes determines the speed of response of such films and is quantitatively measured by the parameter, the effective diffusion coefficient. The objective of the present work is to determine the effective diffusion coefficients for PPy/DBS films prepared by different preparation processes in order to compare the yield values. For this PPy/DBS films were electroplolymerized on Pt wire under galvanostatic mode and electrochemically cycled in 0.1M LiCl aqueous electrolytes. The effective diffusion coefficient for 10 𝜇𝑚 PPy/DBS films prepared as a single layer was found to be 3.315×10−12𝑀2S-1. Whereas it was 9.9433×10−12 𝑀2 S-1 when the same thickness film was prepared as 2 𝜇𝑚 layer by layer rather than single layer. This finding indicates that the speed of response PPy/DBS films improves considerably when it is prepared as layer by layer