Characterization and actuation of ionic polymer metal composites with various thicknesses and lengths

Ionic polymer metal composites (IPMCs) with various thicknesses of 1, 2, 4, and 6 nafion films (denoted as 1-film, 2-film, 4-film and 6-film, respectively) are fabricated, and their characterization and actuation performances are then investigated. The effects of the thickness of the IPMCs on their morphology, surface resistance, and water uptake capability are studied. Their actuation performances are further evaluated by examining the tip force and displacement in terms of the length and the thickness of the IPMCs, under a direct current (DC) power of 3.0 or 4.5 V. In comparison with the 1-film, the 2-film shows a six-fold increase in the maximum tip force, but the response time increases from 2 to 9 s. The 4-film doubles the maximum tip force of the 2-film at 21 s. On the other hand, a reduction of the length of the IPMC from 30 to 15 mm also results in a double-maximum tip force, but this never increases the response time. Repeated actuations of the IPMCs with various thicknesses are performed by three actuation methods of no treatment, treatment in deionized water, and treatment in a NaCl solution. The relationships between the repeated actuation methods and actuations of the IPMCs with various thicknesses are also investigated.