Simultaneously improving the comprehensive insulation performances of super-hydrophobicity, charge migration and surface flashover via atmospheric pressure plasma

With the development of power system, high-speed railway and electric vehicles, insulations face accelerated challenges from higher voltage, harsh natural conditions and unexpected erosions, which puts forward higher requirements for complicated performance of insulation materials. In this study, an adjustable and scalable surface functionalizing method based on surface dielectric barrier discharge (SDBD) plasma was developed to fabricate surface functionally gradient materials (SFGM) of epoxy resin (EP) insulation, and further improve its comprehensive insulating performances. It is demonstrated that the typical Ar/Polydimethylsiloxane (PDMS)/SDBD plasma drives functionally gradient reactions consisting of attenuated fragmenting, grafting and crosslinking on EP surface, thereby fabricating SFGM with continuous gradient physical morphologies and chemical compositions. Results show that the low addition of PDMS leads to the thin film deposition with small particles, in contrast, the excessive addition of PDMS suppresses plasma discharge and leads to the low cross-linked Si[sbnd]O₂ film deposition, which both hinder SFGM performances. Through regulating the addition of PDMS, the optimal plasma discharge is motivated and the optimal Si-O_3–4 insulating surface of SFGM that displays stable super-hydrophobicity, moderate charge migration and the highest flashover voltage is fabricated. Furthermore, based on multi-dimension characterization and analysis, the plasma-driven surface gradient reactions and the effect of reaction medium on material performance are clearly clarified, which provides a scalable fabrication technique and provides guiding insights into the tailoring of insulating materials in industry.