Construction of the Core‐Shell Structure <scp>Ba_xSr</scp>_(1‐x)<scp>TiO₃</scp>‐<scp>CNTs</scp>‐<scp>KH560</scp> to Obtain Dielectric Elastomers With Excellent Dielectric Properties and Large Actuated Strains

ABSTRACT Dielectric elastomers (DEs) tend to require large voltages to obtain large actuated strain, which limits their applications. In this work, barium strontium titanate (Ba x Sr (1‐x) TiO 3 ) was prepared by doping barium titanate (BaTiO 3 ) with different concentrations of Sr 2+ , and the relationship between its dielectric constant and Sr 2+ concentration was investigated. In addition, hydroxylated carbon nanotubes (CNTs) were encapsulated on the Ba 0.5 Sr 0.5 TiO 3 surface to enhance the chemical activity of the particles. The CNTs, with their unique hollow nanostructure and high surface area, significantly improved the dielectric constant of the particles. In addition, the addition of the silane coupling agent KH560 enhances the interfacial interaction between the filler and the polymer matrix, resulting in better dispersion and higher dielectric properties. DE composites were prepared by adding Ba 0.5 Sr 0.5 TiO 3 and Ba 0.5 Sr 0.5 TiO 3 ‐CNTs‐KH560 to nitrile rubber (NBR), respectively. The experimental results show that the dielectric constant of Ba 0.5 Sr 0.5 TiO 3 ‐CNTs‐KH560/NBR is enhanced to 15.59 at 0.9 phr, which is about 1.2 times that of pure NBR (13.0111), and the actuated strain reached a maximum of 13.97% at 0.3 phr Ba 0.5 Sr 0.5 TiO 3 ‐CNTs‐KH560/NBR, which was 4.27 times that of pure NBR (3.27). In this work, the properties of the composites were substantially improved by a small amount of CNTs doping, which provides a new idea for the further preparation of dielectric elastomer materials with large driving strains at low voltages.