Synchronous Cation-Driven and Anion-Driven Polypyrrole-Based Yarns toward In-Air Linear Actuators

Area of Science:

• Materials Science
• Polymer Chemistry
• Textile Engineering

Background:

• Existing textile actuators often rely on three-electrode systems and liquid electrolytes, limiting their practical integration into textiles.
• There is a need for two-electrode yarn-based actuators that can operate synchronously for seamless textile integration.
• Most research focuses on cation-driven conducting polymer (CP) yarn actuators, with limited understanding of anion-driven systems.

Purpose of the Study:

• To investigate the effect of dopants, solvents, and polymer layer combinations on the mechanism and strain of CP-yarn actuators.
• To develop a two-electrode system for textile actuators using dual-acting CP-yarns.
• To demonstrate simultaneous, synchronized actuation of two CP-yarns driven by opposite redox reactions.

Main Methods:

• Fabrication of CP-yarns coated with an inner poly(3,4-ethylenedioxythiophene) (PEDOT) layer and an outer polypyrrole (PPy) layer.
• Systematic study of dopant effects on PEDOT and PPy layers, including anion mobility and charge.
• Electrochemical actuation testing in a two-electrode configuration using different electrolyte solutions.

Main Results:

• The dopant in the inner PEDOT layer significantly influences the actuation mechanism and strain of the outer PPy layer and the overall CP-yarn actuator.
• A PEDOT(Tos)/PPy(ClO4) coated CP-yarn actuated in LiClO4 solution demonstrated pure anion-driven actuation.
• The first demonstration of dual actuation using two CP-yarns doped with different anions (ClO4- and DBS-) exhibiting simultaneous movement with an average strain of 0.5%.

Conclusions:

• The dopant choice is critical for controlling the actuation direction and magnitude in dual-layer CP-yarns.
• Anion-driven actuation mechanisms are viable for developing advanced textile actuators.
• This work paves the way for practical, in-air actuating textile yarns operating in a two-electrode system.