Enhanced Electromechanical Performance of Dielectric Elastomer by Co-Crosslinking of Silane-Functionalized TiO₂ with...

Dielectric elastomer actuators (DEAs) are attracting much attention as candidates for next-generation flexible actuation. Among various DE matrices, polyacrylate rubber (AR) is especially promising owing to their intrinsically high dielectric constant (ε_r) and good mechanical performance. In particular, its mechanical behavior is close to that of porcine bladder tissue, making it a potentially good material for soft biomedical actuators for artificial bladder constructs. To achieve high actuated strain, which requires high ε_r, high breakdown strength, and low elastic modulus, an AR DE composite filled with silane-functionalized TiO₂ was fabricated, exhibiting good electromechanical performance enabled by strengthened interfacial polarization. To improve compatibility between TiO₂ and AR matrix, TiO₂ was preferentially modified with a silane coupling agent (CA) that features a double bond as its functional group, which can be introduced on TiO₂ surface and participate in vulcanization with AR, thereby forming co-crosslinking bridges that strengthen interfacial bonding, improve filler dispersion, and increase interfacial polarizability within the matrix. As a result, at relatively low filler loadings, the composite exhibits a significantly increased ε_r, while maintaining low modulus, low dielectric loss and high elasticity. The 10 CA@TiO₂/AR composite exhibits a maximal actuated strain of 7.9% at 31.9 kV/mm without pre-stretch, which is 1.48 times that of pure AR and 1.32 times that of the 10 TiO₂/AR composite.