Self-assembled wide bandgap nanocoatings enabled outstanding dielectric characteristics in the sandwich-like structure polymer composites

Polymer dielectrics are insulators or energy storage materials widely used in electrical and electronic devices. Polymer dielectrics are needed with outstanding dielectric characteristics than current technologies. In this study, the self-assembly of boron nitride nanosheets (BNNSs) was applied to form an inorganic–organic nanocoating on various common polymer dielectrics. It is inexpensive and easy to fabricate this thin coating on a large scale. The coating has a wide bandgap and thus can significantly improve the breakdown strength of polymer dielectrics. The charge characteristics and trapping parameters of nano-domains on the surfaces of polymer dielectrics were measured, and the coating had shallow trap levels. This facilitated the dissipation of surface charges and thus greatly increased the flashover voltage. The coating also effectively improved the temperature stability and dielectric constant of the polymer dielectric. This nanocoating shows potential as a method to effectively improve the dielectric characteristics of polymer dielectrics and outperform existing composite polymer dielectrics, which are crucial for large-scale applications in energy storage and power and electronic devices. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40580-022-00346-2.