Bending control of Nafion-based electroactive polymer actuator coated with multi-walled carbon nanotubes

Electrical bending control of Nafion-based ionic polymer–metal composite (IPMC) is quite difficult. Unlike a conventional fully hydrated noble metal-coated Nafion type IPMC, however, highly dehydrated silver-coated Nafion type IPMC exhibited better electrical bending controllability. Embedding of the multi-walled carbon nanotube (MWCNT) into Nafion surface promoted adsorption of a larger quantity of silver on the Nafion surface, since the MWCNT surface served as adsorption sites for silver. A MWCNT-embedded Nafion coated with such a large quantity of silver (SCNT-Naf) exhibited large bending curvature under an applied voltage when in a highly dehydrated state, because of large scale induction of silver redox reaction. We could even achieve autonomous bending curvature control of the highly dehydrated SCNT-Naf quantitatively by automatically monitoring total charge imposed on it.