Polypyrrole Asymmetric Bilayer Artificial Muscle: Driven Reactions, Cooperative Actuation, and Osmotic Effects

Abstract

The coulo‐dynamic (angle/consumed charge) characterization of an asymmetric polypyrrole (PPy) bending bilayer (PPy 1 /PPy 2 ) muscle is performed in aqueous solutions by cyclic voltammetry with parallel video recording of a reversible angular displacement of 200°. The characterization of each of the two PPy 1 /tape, PPy 2 /tape muscles, describing 30° and 50° per voltammetric cycle, corroborates the driven muscle reactions and ionic exchanges. The asymmetric bilayer efficiency, as described degrees per reaction unit, is seven and four times that of the PPy/tape muscles. A cooperative electro‐chemo‐mechanical actuation of each of the individual layers occurs in the asymmetric bilayer. Each of the three muscles is a Faradaic polymeric motor: described angles are linear functions of the consumed charge with small hysteresis loops. Each loop is related to dynamic water osmotic balance following the reaction driven film swelling or its fast electro‐osmotic expulsion around the reduction induced conformational closing and film compaction.