Electric-field-actuation of in situ composites that contain silver-coated carbon fibers in sodium sulfonate ionomers
In this research contribution, an electric-field-stimulated actuation system was developed by impregnating sodium-sulfonated ionomers, poly(styrene-co-butyl acrylate-co-sodium allyl sulfonate, PSBS) with in situ deposited silver-modified carbon fibers (SCCF). In the actuator, PSBS acts as an electrolytic medium for metal ion migration, and the SCCFs act as surface conductive electrodes on both sides of a sandwich configuration. The maximum bending angle of 98° is achieved after 11 s of stimulation when the electric potential difference is 5 V. This novel actuator has two outstanding characteristics: (1) in situ deposited SCCFs in PSBS form double-sided surface electrodes with high conductivity (10−3 Ω cm) and good interfacial binding with the PSBS matrix, which minimizes the drawbacks of electrochemical plating or electrode-less deposition of noble metals like Pt on the membrane surface of ionic polymer metal composites (IPMCs); and (2) it has the highest bending rate compared to currently existing IPMCs including Nafion and novel ones published recently. Additionally, the storage E′ and loss E′′ moduli of the PSBS–SCCF actuation system can be adjusted by selecting the appropriate ratio of butyl acrylate to styrene, where the latter comonomer increases the rigidity of the composite. The bending angle of this actuator can be controlled by the electric potential difference, water-uptake, and terpolymer composition. This fabrication technology exhibits significant advantages, such as process simplicity using non-toxic and low cost materials, rapid response, large bending angles, and reproducibility.