Study Of Preparation And Electromechanical Properties Of Silicone Rubber-based Dielectric Elastomer Composites Containing Core-shell Functional Nano-particles

Dielectric elastomer(DE)material is a kind of soft smart material that deforms under the action of an electric field and can recover its shape when the electric field is removed,thereby realizing the conversion of electrical and mechanical energy.With its good flexibility,light weight,large actuation deformation and easy processing features,DE materials have excellent application prospects in many fields such as bionics,medical rehabilitation,robotics,optics,and aerospace.However,the commercial application of DE materials is still in an immature stage.Therefore,it is necessary to prepare dielectric elastomer materials with a lower driving voltage and a greater driving deformation.The research content of this paper is as follows.In order to increase the interface in the composites,enhance the interfacial polarization effect and improve the compatibility between phases,a model of“the dielectric constant of the core-shell-matrix material gradually decreases layer by layer”was proposed and constructed.The influence of this model composed of different types of cores and shells on the dielectric,mechanical and driving properties of dielectric elastomer materials was investigated.(1)'core-semiconductor material,shell-insulating material'-silicon dioxide(SiO₂)coated titanium dioxide(TiO₂)composite silicone rubber(PDMS)dielectric elastomer composites.TiO₂@SiO₂ nanoparticles were prepared by coating silica on titanium dioxide by hydrolysis of ethyl orthosilicate(TEOS).The TiO₂@SiO₂/PDMS composite was prepared by adding core-shell nanoparticles into the silicone rubber by the method of solution blending.The dielectric constant of 16 vol.%TiO₂@SiO₂/PDMS composite is 8.91(100 Hz)which is 3.16 times that of pure PDMS,and the electro-driven strain at 30 V??m^-1 is 6.08%,which is higher than pure PDMS by 180%.(2)'core-conductive material,shell-insulating material'-silicon dioxide coated carbon nanotubes(CNTs)silicone rubber dielectric elastomer composites.CNTs@SiO₂(CS)core-shell nanoparticles were synthesized by hydrolysis of ethyl orthosilicate,and CS/PDMS composites were prepared by the solution blending method.It is found that the filling of CS into the PDMS matrix not only increased the dielectric constant,but also suppressed the dielectric loss(<0.04).(3)'core-ceramic material with high permittivity,shell-semiconductor material'-titanium dioxide coated barium titanate silicone rubber dielectric elastomer composites.BaTiO₃@TiO₂nanoparticles were prepared by coating titanium dioxideon barium titanate(BaTiO₃)by hydrolysis of tetrabutyl titanate(TBOT).The BaTiO₃@TiO₂/PDMS composite was prepared by solution blending method.Different from the above two composite,the breakdown strength of BaTiO₃@TiO₂/PDMS composites increases with the increase of filler content,and the elongation at break is hardly affected by the filler content.When the filler loading is 15 wt.%,the BaTiO₃@TiO₂/PDMS composite has the largest actuated deformation of 3.3%(30 V??m^-1).In summary,a reasonably designed model of“the dielectric constant of the core-shell-matrix material gradually decreases layer by layer”not only improves the dielectric constant and breakdown strength of DE composites,but also suppresses the dielectric loss.In addition,it also improves the low electric field electro-driving performance of DE composites.This has a good reference significance for the application of dielectric elastomer actuators.