Heat-triggered Self-healing Cross-linked Poly(silicone-urea)s with Recoverable Dielectric Performances

Silicone rubbers containing dynamic hindered urea bonds is a potential material for mechanical damages in power equipment. In this work, poly(silicone-urea)s based on isocyanate-piperazine fabricated dynamic hindered urea bonds was synthesized. Insulating performances of materials with different crosslinking density adjusted by the ratio of polydimethylsiloxane and glycerol were also investigated. It was found that higher crosslinking density could improve dielectric properties remarkably. Moreover, the insulating properties can be recovered through healing mechanical scratches due to the dissociative-associative effect of chemical bonds under mild conditions. The permittivity, dielectric loss, and DC volume resistivity of the polymers have not changed significantly after cut-healing. This proves that constructing a reversible chemical bond is a workable method to prepare self-healing insulating materials.