Self‐Repairable, High Permittivity Dielectric Elastomers with Large Actuation Strains at Low Electric Fields

Abstract

A one‐step process for the synthesis of elastomers with high permittivity, excellent mechanical properties and increased electromechanical sensitivity is presented. It starts from a high molecular weight polymethylvinylsiloxane, P1, whose vinyl groups serve two functions: the introduction of polar nitrile moieties by reacting P1 with 3‐mercaptopropionitrile (1) and the introduction of cross‐links to fine tune mechanical properties by reacting P1 with 2,2′‐(ethylenedioxy)diethanethiol (2). This twofold chemical modification furnished a material, C2, with a powerful combination of properties: permittivity of up to 10.1 at 104 Hz, elastic modulus Y10% = 154 kPa, and strain at break of 260%. Actuators made of C2 show lateral actuation strains of 20.5% at an electric field as low as 10.8 V μm–1. Additionally, such actuators can self‐repair after a breakdown, which is essential for an improved device lifetime and an attractive reliability. The actuators can be operated repeatedly and reversibly at voltages below the first breakdown. Due to the low actuation voltage and the large actuation strain applications of this material in commercial products might become reality.

Self-Healing, High-Permittivity Silicone Dielectric Elastomer

“…Only a few approaches to self-healing dielectric elastomers have been presented to date, [6][7][8] and although multiple approaches to self-healing polymers and elastomers based on for example metal complexes 9 , ionomers 10,11 , hydrogen-bonding 12,13 , π-π stacking 14 and supramolecular assemblies 15,16 have been developed, there has been no focus on dielectric properties. 17 Recently, we presented a novel class of interpenetrating silicone and ionic networks exhibiting increased dielectric permittivity.…”

Mechanics of dielectric elastomers: materials, structures, and devices

“…In a recent study, synthesis of silicone elastomers with optimized molecular weight, cross-linker, and silica has produced DEs with high permittivity and large actuation strain, which can repeatedly function at an electric field as low as 10.8 V per μm (Dünki et al, 2015). Interestingly, atomic force microscopy-based studies have demonstrated that the energy density of individual dormant cells (i.e., Bacillus spores) in response to cyclic humidity variations is at least one order of magnitude higher than any synthetic materials including DEs .…”

Fully printed 3 microns thick dielectric elastomer actuator

“…This result is the highest reported value for a DEA, improving by more than one order of magnitude over current state-of-the art devices 1 . While area strain of 488% 21 and actuation at only 10 V/m 15 have been reported for expanding circle DEAs, the corresponding strain-to-voltage-squared ratios were only 5.7%/kV 2 and 7%/kV 2 respectively. (ii) The average radial strain was measured on 3 m and 30 m thick DEAs.…”

“…The Young's modulus and dielectric permittivity of elastomers can be engineered 11 using different techniques such as the addition of plasticizers 12 and fillers 13,14 . It is only recently that significant improvement was reported over typical DEA materials, synthesizing an elastomer with high dielectric permittivity and good mechanical properties 15 . The reported actuator was however based on a 180 m thick membrane and required 1 kV to reach a lateral strain of 7%.…”