The improved low-field electro-actuation of dielectric elastomer composites regulated by entirely-inorganic BaTiO3@TiO2 core-shell construction

Dielectric elastomer (DE) as an important electro-active polymer (EAP), is capable of providing a large elastic deformation under an external electric field. However, the excellent electro-actuated performance is usually obtained under high electric fields, which greatly limits the practical application range of DE, especially in the field of in vivo organisms. Thus, it is essential to make a reasonable structural regulation to achieve an effectively improved electro-actuation of DE materials under low driving electric fields. Herein, a typical BaTiO3@TiO2 entirely-inorganic core-shell construction was prepared through the micro-emulsion method. Meanwhile, a series of polydimethylsiloxane (PDMS)-based DE composites incorporated with different fractions of BaTiO3@TiO2 were synthesized by solution blending and compression molding. The BaTiO3@TiO2 core-shell construction endows DE composites with an enlarged heterogeneous interface and enhanced interfacial polarization synchronously, which is also benefit to maintain the flexibility of DE materials. The buffer effect offered by TiO2 shell is helpful to alleviate the local electric field concentration at the fillers-matrix interface in DE when being withstood an exponentially-growing electric field. Specifically, the maximum electro-actuated strain of 21% under a low electric field (40 V.mu m(-1)) is obtained from the DE composite filled with 4 wt% BaTiO3@TiO2, which is 290% higher than that of pristine PDMS (5.38% at 40 V.mu m(-1)). It is shown that the well-designed inorganic core-shell construction can effectively improve the electromechanical conversion capability of DE composites. This study provides a promising approach to obtain an optimized electro-actuation under low electric fields.