Conducting Polymers

Abstract

Soft actuators based on conducting polymers are discussed in terms of strain, stress and stability taking the mechanism into consideration. The actuation is generated by the insertion of anions from the electrolyte solution, which is triggered by electrochemical redox reactions. Characteristics of the actuation in polypyrrole, polyaniline, polythiophene, and poly(3,4-ethylenedioxythiophene) (PEDOT) are described. The maximum strain and stress are reported to be 39.9 % and 22 MPa, respectively, in polypyrrole actuator. However, the strain is usually less than 10 %. The stress (contraction force) originates from the elasticity of conducting polymers or Young's modulus. Creeping under tensile loads, which is intimate issue in soft actuators, is discussed in terms of conformation change of polymer chains and shape memory effect. The actuation generated by sorption and desorption of moisture controlled with electrical heating is also introduced with the mechanism and characteristics.

Versatile Actuators Based on Polypyrrole-Coated Metalized Eggshell Membranes

“…Conducting polymers (CPs) have been widely used as key active component materials for soft actuators owing to their intrinsic characteristics, namely, low power requirements, response to different stimuli, flexibility, etc. , With such features as a high electrochemomechanical activity, and high strain and stress for various applied stimuli, , polypyrrole (PPy) is the most used CP in the fabrication of the actuators. − Besides, due to its biocompatibility, this CP is an interesting choice for biomedical applications. − An enhancement of the actuation performances (displacement, bending angle, and response time) of the fabricated devices can be achieved using actuating platforms which contain high active surface structures (membranes, , tubes, or fibers) that can facilitate the ion diffusion in the PPy films. Also, in air, PPy can undergo a rapid bending due to sorption of water vapors or a contraction because of desorption of these vapors caused by Joule heating, an effect induced by application of a voltage. ,, Usually, the actuators working in air have a trilayer configuration consisting of two PPy films separated by an electrolyte membrane − or a solid ion source. , Additionally, PPy can be easily obtained under different morphologies and configurations by simple chemical and electrochemical methods using low-cost raw materials …”

“…Conducting polymers (CPs) have been widely used as key active component materials for soft actuators owing to their intrinsic characteristics, namely, low power requirements, response to different stimuli, flexibility, etc. 10,11 With such features as a high electrochemomechanical activity, and high strain and stress for various applied stimuli, 10,11 polypyrrole (PPy) is the most used CP in the fabrication of the actuators. 12−19 Besides, due to its biocompatibility, this CP is an interesting choice for biomedical applications.…”

“…Also, in air, PPy can undergo a rapid bending due to sorption of water vapors or a contraction because of desorption of these vapors caused by Joule heating, an effect induced by application of a voltage. 10,15,26 Usually, the actuators working in air have a trilayer configuration consisting of two PPy films separated by an electrolyte membrane 27−30 or a solid ion source. 31,32 Additionally, PPy can be easily obtained under different morphologies and configurations by simple chemical and electrochemical methods using low-cost raw materials.…”

Research Progress on Conducting Polymer-Based Biomedical Applications

“…On the other hand, when large anions, such as dodecylbenzenesulfonic (DBS − ) acid, are used, long alkyl chains of the anions cause entanglement and immobilization in the network. The reduction of the CPs then occurs via the cation drive, where cations inserted from the electrolyte solution result in a swollen polymer network by the volume of additional cations (Figure 6b) [131]. In actuators, a linear or angular movement can be derived from the volumetric change of the CPs.…”

“…Electrochemomechanical reactions using small anions result in the shrinking of CPs upon reduction by anion drive (a), whereas large anions cause CPs to swell when reduced by cation drive (b). Reprinted with permission from[131]. Copyright 2014 Springer.…”