High Electromechanical Response of Ionic Polymer Actuators with Controlled‐Morphology Aligned Carbon Nanotube/Nafion Nanocomposite Electrodes

Abstract

Recent advances in fabricating controlled-morphology vertically aligned carbon nanotubes (VA-CNTs) with ultrahigh volume fraction create unique opportunities for markedly improving the electromechanical performance of ionic polymer conductor network composite (IPCNC) actuators. Continuous paths through inter-VA-CNT channels allow fast ion transport, and high electrical conduction of the aligned CNTs in the composite electrodes lead to fast device actuation speed (>10% strain/second). One critical issue in developing advanced actuator materials is how to suppress the strain that does not contribute to the actuation (unwanted strain) thereby reducing actuation efficiency. Here our experiments demonstrate that the VA-CNTs give an anisotropic elastic response in the composite electrodes, which suppresses the unwanted strain and markedly enhances the actuation strain (>8% strain under 4 volts). The results reported here suggest pathways for optimizing the electrode morphology in IPCNCs using ultra-high volume fraction VA-CNTs to further enhanced performance.

Carbon Nanotube and Graphene‐based Bioinspired Electrochemical Actuators

“…[ 100 ] In 2010, Zhang et al improved the strain level and actuation speed by using vertically aligned carbon nanotubes (VA-CNTs)/nafi on composite electrodes. [ 41 ] In this work, VACNTs were prepared by a modifi ed chemical vapor deposition (CVD) method. Then, it was densifi ed by mechanical biaxial densifi cation ( Figure 9 ).…”

“…In some cases, in order to ensure the homogeneous electric fi eld and lower the voltage drop, another thin layer of metal is sputtered on the carbon electrode surface. [ 41 ] Common IPMC electrodes can be classifi ed into two categories: carbon based [ 46,52,53 ] and carbon-polymer based electrodes. [54][55][56] The polymer referred here mainly acts as an additive for better fi lm formation and adhesion to electrolyte layer.…”

Force optimization of ionic polymer metal composite actuators by an orthogonal array method

“…An anisotropic surface texture of the Nafion membrane was obtained by polishing with an abrasive material. The third step (ion adsorption) was to soak the ionic polymer in a salt solution to allow platinum-containing cations ([Pt(NH 3 ) 4 ] 2+ ) to diffuse through via an ion-exchange process [22]. The fourth step (reduction) was to reduce the platinum complex cations adsorbed in the Nafion membrane to the metallic state in the form of nanoparticles, by using reducing agents such as NaBH 4 [23].…”

“…However, because of the high driving voltage, relatively small stroke, low frequency and large energy consumption, these materials may not satisfy the needs of microrobots and MEMS for high flexibility, redundancy rate and load/weight ratio. Thus the artificial muscle with low driving voltage and large deformation has experienced rapid growth in academic interest and industrial application [4,5]. Since Oguro's group reported bending behavior in an applied electric field for the first time in 1992 [1], ionic polymer metal composites (IPMCs), also termed "artificial muscle", are considered to be one of the most promising EAPs (electroactive polymers), and have experienced rapid growth in academic interest and industrial application.…”

“…Thus the artificial muscle with low driving voltage and large deformation has experienced rapid growth in academic interest and industrial application [4,5].…”