Synthesis And Characterization Of Titanium Dioxide Modified Self-Healing Dielectric Elastomers

Self-healing is of great significance in ensuring that materials exhibit safety and reliability in service,while resisting cracks and breaks from repetitive use.Specifically,endowing dielectric elastomer with self-healing property is quite utility for the tolerance of dielectric breakdowns and operation again after first dielectric failure.As the result,the service life of material will be extended.Hydrogen bonds as one of the non-covalent bonds were used to design intrinsic self-healing supramolecular materials,because of their directionality,excellent reversibility,simplicity in chemistry and the wide range of application.Silicone elastomer as a dielectric elastomer was used to be used for dielectric self-healing elastomers in the past several years.In this paper,a self-healing dielectric elastomer was prepared by introducing a dielectric filler into a synthesized elastomer with intrinsic self-healing properties.First,The TiO2/urea particles were synthesized by a hydrolysis method.The results of SEM and FTIR indicated that the TiO2/urea core-shell structure particles have been successfully fabricated.Then,we developed a new self-healing dielectric elastomer with TiO2/urea core-cell particles and supramolecular elastomer which was synthesized with small molecular biological acids,DETA and urea.FTIR and 1H NMR test results showed that the urea on outer shell of TiO2 particles can form hydrogen bond interaction with molecular chains,so the TiO2/urea core-cell particles in supramolecular system not only prevented urea from extended the length of chain but also increase the amount of monoalkyl-urea groups,which is consistent with the change of glass transition temperature in the result of DSC and the crystal structure in the result of XRD.Self-healing performance analysis found that the sample with lwt%TiO2/urea particles(TuSE-1%)could achieve mechanical,dielectric and electromechanical properties healed simultaneously within 24 h at room temperature.The mechanical properties test showed that TuSE-1%exhibit the lowest tensile strength and the lowest modulus;the sample with swt%TiO2/urea particles(TuSE-5%)exhibit the lowest hysteresis loss.The dielectric properties test found that TuSE-5%had the largest dielectric constant of 37.5 at 103 Hz,which has increased 247%compared with the blank sample.Electromechanical properties showed that the lateral actuation strain of TuSE-1%reached 7.53%at 8.5 V μm-1.In addition,the experimental results also confirmed that the TiO2 coated with urea has better modification effect on supramolecular elastomer which exhibit better performance compared with the materials generated by pure TiO2 and commercial nano-and micro-TiO2 as filler.