Soft Gel Filler Embedded Elastomer with Surfactant Improved Interface for Dielectric Elastomer Actuators

Abstract

Stretchable materials are the foundation of dielectric actuators (DEAs) for artificial muscle. However, the inadequate dielectric constant of stretchable materials has always greatly limited the performance of artificial muscle. Recently, soft fillers have been proposed to improve the dielectric property and preserve the stretchability for softness, aiming to avoid the stiffening effect of traditional rigid fillers. As composites, an amount of interfacial region is generated, which remarkably affects composites’ performance from dielectrics to mechanics. Herein, we demonstrate that the size effect, interfacial binding, and compatibility have a great impact on soft filler doped composites. Particularly, according to the liquid characteristics of soft fillers, we explore an interfacial modification method using surfactants. Composite breakdown strength is thus enhanced 2.2-fold from that in the control group due to the reduction of mismatch between fillers and matrix. Moreover, surfactants alleviate the well-known stiffening effect in small fillers. The area strain of the composites reaches 10.3 ± 0.4% at a low electric field of 7 MV/m, and a soft micropump is successfully assembled. These findings demonstrate a unique and combined interfacial influence of soft filler doped elastomer, which promotes the advancements of the dielectric elastomer artificial muscle.

Preparation of PANI/CuPc/PDMS Composite Elastomer with High Dielectric Constant and Low Modulus Assisted by Electric Fields

“…In order to generate a larger drive at a relatively low driving voltage, the dielectric constant can be increased by adding a high dielectric filler, such as ceramic fillers (BaTiO 3 , SnO 2 , and Al 2 O 3 ) or conductive fillers (carbon fibers, carbon black, metal powder, polyaniline, and polypyrrole) and so on [ 12 , 13 , 14 , 15 , 16 , 17 ]. The composites filled with ceramic particles require higher filler content to achieve a high dielectric constant, and this results in decreased flexibility [ 18 ]. For the composites filled with conductive fillers, the dielectric loss increases rapidly as the dielectric constant increases since the percolation threshold exists, which brings instability to practical applications.…”