A membrane actuator based on an ionic polymer network and carbon nanotubes: thesynergy of ionic transport and mechanical properties

Abstract

There is a growing interest in the development of ionic polymer–metal composites(IPMC) as sensors and actuators for biomedical applications due to their largedeformation under low driving voltage. In this study, we employed poly(vinylalcohol)/poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PVA/PAMPS)blend membranes as semi-interpenetrating polymer networks for ion exchange inIPMC construction. To improve the mechanical and electrical properties of theIPMC, multi-walled carbon nanotubes (MWNT) were added into PVA/PAMPSmembranes. The actuator performance of the membranes was measured as a function oftheir water uptake, ion exchange capacity, ionic conductivity and the amount ofMWNT in the membrane. The dispersion quality of the modified MWNT in thePVA/PAMPS membrane was measured using transmission electron microscopy. Thecantilever-type IPMC actuator bends under applied voltage and its bending angle andthe generative tip force were measured. Under an applied voltage, IPMC with∼1 wt% MWNT showed the largest deflection and generated the largest blocking tip forcecompared with those of IPMC with other various amounts of MWNT. These results showthat a small addition of MWNT can optimize the actuation performance of IPMC. Theresult indicates that IPMC with MWNT shows potential for use as biomimetic artificialmuscle.