Remarkable improvement of the electro-mechanical properties of polydimethylsiloxane elastomers through the combined usage of glycerol and pyridinium-based ionic liquids

The issue of high driving voltages limits the commercial application of dielectric elastomer transducers, but increasing dielectric permittivity and reducing the Young’s modulus of elastomers is a means of lowering this driving voltage. However, dielectric elastomer fabrication, which fulfills simultaneously high dielectric permittivity and a low Young’s modulus, is difficult.

In this study, we explore the combined usage of ionic liquids and glycerol as soft fillers with high dielectric permittivity in silicone-based elastomers. We also fabricate a foamed structure in silicone elastomers to lower further the Young’s modulus of the elastomers. Surprisingly, it is found that nitrogen atoms in the cations of ionic liquids (ILs) do not inhibit the platinum (Pt)-catalysed hydrosilation of silicone elastomers when ILs are dissolved in glycerol.

The effect of molecular structure and the amount of ILs on the electrical breakdown strength, rheological, dielectric and mechanical properties of silicone-based elastomers is analysed herein. Compared to the pure elastomer, the combined usage of 5% 1-butyl-4-methylpyridinium tetrafluoroborate with 10% glycerol can improve the relative ratio of dielectric permittivity to the Young’s modulus almost eleven-fold at a given electrical field below the electrical breakdown field.