Ternary silicone dielectric elastomer micro-nanocomposites with enhanced mechanical and electromechanical properties

In this paper, ternary silicone dielectric elastomer micro-nanocomposites were prepared by mixing barium titanate (BT) nanoparticles or 3-mercaptopropylethoxy-bis(tridecyl-pentaethoxy-siloxane) (Si747)-modified BT (BT-Si747) with hexagonal boron nitride (BN) microplatelets into methyl vinyl silicone rubber (MVSR). BN platelets as physical barriers improve the dispersion of BT nanoparticles, so the MVSR/BT/BN composites achieve the higher electric breakdown field. The Si747 in MVSR/BT-Si747/BN composites can be grafted on BT nanoparticles surface while the mercapto groups of Si747 can react with double bonds of MVSR, which increases interfacial interaction to improve the mechanical property. As a result, the tensile strength and elongation at break of MVSR/30 wt%BT-Si747/30 wt%BN composite are 3.43 MPa and 2705%, which is 2.4 and 4.4 times as high as the MVSR/30 wt%BT/30 wt%BN composite, respectively. The MVSR/BT-Si747/BN composites exhibit higher actuation performance under lower electric fields due to simultaneous increase in dielectric constant and decrease in elastic modulus. The MVSR/10 wt%BT-Si747/10 wt%BN composite obtains an actuated strain of 8.81% at 47.48 kV/mm, which is twice as high as pure MVSR (4.4% at 60.21 kV/mm). The used method in this experiment is simple, effective, and low cost, and prepared ternary micro-nanocomposites have potential applications in dielectric actuators.