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 (PPy1/PPy2) 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 PPy1/tape, PPy2/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.

Construction and coulodynamic characterization of PPy-DBS-MWCNT/tape bilayer artificial muscles

“…[1][2][3][4][5][6] During the oxidation/reduction of the electroactive material counterions and solvent molecules are exchanged with the electrolyte to keep the charge balance inside the film and the osmotic balance between the material and the electrolyte. [10][11][12][13][14][15] They are electro-chemo-mechanical transducers. Bending bilayer artificial muscles transduce minor reaction-driven ionic exchanges into large angular (> 30°) displacements.…”

Structural and Conformational Chemistry from Electrochemical Molecular Machines. Replicating Biological Functions. A Review

“…The use of metal electrodes supporting the film use to give open coulovoltammetric responses revealing the presence of irreversible reactions at the metal/polymer interface, as water or moisture electrolysis to produce hydrogen at high cathodic potentials or oxygen at high anodic potentials ,,. Similar results were obtained from self‐supported films of blends of conducting polymers with organic macroions or polyelectrolytes ,,,,,…”

“…Those films of conducting polymers with large amphiphile anions or polyelectrolytes following reaction 2 show, beyond a reduction threshold (swollen gel) a new structural change is presented by voltammetric, coulovoltammetric and chronoamperometric responses ,,,. The process is related to the high water content and has been attributed to the formation of vesicles or lamellas,, whose corroboration requires some new evidences and should open a new field for encapsulated biomimetic reactions and for artificial vacuolar transportation.…”

Self-Supported Polypyrrole/Polyvinylsulfate Films: Electrochemical Synthesis, Characterization, and Sensing Properties of Their Redox Reactions

“…Self‐supported electrodes were prepared by painting a transversal line, with a width of 1 mm, around the polymer strip and close to the film top. The paint closed the polymer pores, which therefore avoided movement of the solution by capillarity towards the metallic electric contact at the top and, at the same time, allowed good electronic conductivity through it . The film was immersed into the electrolyte by keeping the transversal paint strip above the solution.…”