As emerging smart polymers, ionic polymer-metal composites (IPMCs) are playing more and more important roles as promising candidates for next-generation actuators in terms of academic interest and industrial applications. It is reported that the actuation behaviors of IPMCs are dependent on the electrochemical kinetic process between metal/polymer interfaces to a great extent. Thus, the fabrication of tailored metal/polymer interface electrodes with large surface areas and superior interface characteristics is highly desirable in improving the actuation performance of IPMCs, which is still technologically critical for IPMCs. In this contribution, we developed a novel fabrication technology for carbon/metal composite electrodes with a superior interface structure and characteristics to optimize the actuation behaviors of IPMCs by exploiting the synergistic effect of combining a sulfonated multi-walled carbon nanotube (SCNT)/Nafion hybrid layer with nanodispersed Pd particles. The improved IPMCs showed significantly enhanced capacitance characteristics and highly facilitated charge-discharge processes. Moreover, their actuation behaviors were greatly improved as expected, including approximately 2.5 times larger displacement, 3 times faster deformation speed, 4 times greater output force, and 10 times higher volume work density compared to those of the IPMCs with traditional electrode structures. The advantages of the developed SCNT/Pd-IPMCs will greatly facilitate their applicability for artificial muscles.
Keywords: IPMC; actuation behavior; composite electrode; electrochemical characteristics; smart polymer.