Insights into the synergistic effect of methoxy functionalized halloysite nanotubes for dielectric elastomer with improved dielectric properties and actuated strain

Abstract

The application of silicone rubber (SiR) as a dielectric elastomer acuator is limited by its poor actuated strain because of low dielectric constant (εr). Herein, we designed and synthesized SiR-based dielectric elastomer composites with high εr and acuated strain by introducing an extraordinary designed filler, methoxy functionalized halloysite nanotubes (HNTs-IPTS). This novel filler exhibits synergistic effects: (i) Highly polar urethane groups modified on the surface of HNTs-IPTS endow the composites with excellent dielectric properties (εr = 13.59@0.1 kHz). (ii) The covalent bonds formed between HNTs-IPTS and SiR provide the composites with enanced tensile strength, better filler dispersion, and lower dielectric loss. (iii) The tubular architecture of HNTs-IPTS promotes the efficient delivery of charge carriers, further improve the εr and actuated strain of the composites. These merits allow the resulting actuator to be more sensitive to driving field. Finally, HNTs-IPTS/SiR composites at 9 phr filler content exhibited a quite large actuated strain of 22.7% at 36.37 kV/mm without any prestrain. This work establishs the efficient HNTs-IPTS via structure design strategy, and the HNTs-IPTS/SiR composites are of great potential for next-generation DE acuators.