Enhanced Electromechanical Performance of Natural Rubber Composites via Constructing Strawberry-like Dielectric Nanoparticles

Dielectric elastomer actuators (DEA) were widely applied in the field of sensors, artificial muscles, and microrobotics as they can convert electrical energy into mechanical energy. In this work, we have designed strawberry-like barium titanate/tannic acid-ferric ion/silver (denoted as BT/TA-FeIII/Ag) dielectric nanoparticles to improve the electromechanical performance of natural rubber (NR)-based composites. In the first instance, BT nanoparticles were modified by TA by introducing catechol- and pyrogallol-type phenols, which can be complexed with FeIII to form a coating of TA-FeIII on the surface of the BT nanoparticles (denoted as BT/TA-FeIII). Then, Ag nanoparticles were deposited on the surface of BT/TA-FeIII by the reduced Ag+ via an electroless plating method. The addition of BT/TA-FeIII/Ag nanoparticles in the NR matrix enhanced the electromechanical sensitivity of NR-based composites and thus increased the actuation strain of NR-based composites. In addition, the discontinuous silver layer deposited on the surface of BT/TA-FeIII/Ag nanoparticles maintained good insulation of NR-based composites. In the final step, a high actuation strain (15.3%) was achieved by NR-based composites filled with 10 phr BT/TA-FeIII/Ag at a low electrical field (62.2 kV/mm), which was about 2.2 fold larger than the actuation strain of the pure NR (about 7.0% at 54.7 kV/mm). Overall, this strategy could provide insights for the preparation of dielectric elastomers with high actuation strain driven by a low voltage.