Ionic polymer–metal composite bending actuator loaded with multi-walled carbon nanotubes

Multi-walled carbon nanotube (M-CNT)/Nafion nanocomposites were prepared by the dispersion of treated M-CNTs in a Nafion solution; this procedure was done in order to evaluate the influence of M-CNT loading of up to 7 wt.% on the M-CNT distribution behavior, mechanical properties, and the related actuation performance of the composites. As the M-CNT loading rose above 1 wt.%, the uniformly distributed M-CNT bundles induced by the Nafion polymer were determined to be perturbed, resulting in an inhomogeneous distribution. The heterogeneously distributed M-CNT bundles may provide an undesired impact on the connectivity within the Nafion membrane, thus giving rise to the poor electrochemically-generated actuation properties. It is important to note that the nanocomposite having only a 1 wt.% of M-CNT loading exhibited the best actuation performance in terms of the blocking forces produced by the M-CNT nanocomposites in a cantilever form. It can be understood that the performance improvement is caused by the uniform distribution of the M-CNT bundles, which was confirmed by TEM, XRD and electromechanical actuation tests. It is concluded that the M-CNT distribution behavior, induced by interactions between the polymer matrix, Nafion and the M-CNTs and the related electromechanical performance of the composites, are mainly governed by the M-CNT content. Also, DMA testing was performed.