Sulfonated polystyrene-based ionic polymer–metal composite (IPMC) actuator

Herein, we report the actuation performance of a cost-effective sulfonated polystyrene (sPS)-based IPMC, and its comparison with that of a Nafion-based IPMC. It was observed that the current density (810 vs. 456 mA/cm2), the tip displacement (ca. 44 vs. 23 mm), the response rate (ca. 10.3 vs. 2.9 mm at starting 3 s) and the blocking force (ca. 2.76 vs. 1.51 gf) were significantly higher for the sPS-IPMC compared to those for the Nafion-IPMC. Additionally, the sPS-IPMC showed very slow back relaxation. With the aid of the scanning electron microscopy for the morphological analysis and various methods for quantitative analysis, we found that the excellent electromechanical response of the sPS-IPMC was due to the smoother and thicker electrode layer, the higher tensile modulus, the enhanced hydraulic force based on the higher water uptake and higher ion exchange capacity (IEC) value than those of the Nafion-IPMC. The sPS-based IPMCs seem to be one of the promising alternatives of the conventional expensive IPMCs.