Robust Hydrophobic PMIA Nanopaper with Enhanced Flashover Resistance via Plasma and Nano-SiO2 Co-modification

Poly(m-phenylene isophthalamide) (PMIA) nanopaper exhibits remarkable thermal stability, excellent electrical insulation properties, and high mechanical strength, making it broad application prospects in high-voltage power systems. Nevertheless, its inherent hydrophilicity derived from amide groups facilitates moisture adsorption, leading to reduced insulation properties under humid conditions. This study presents a synergistic surface modification strategy integrating plasma modification and nano-SiO₂ coating to concurrently enhance the hydrophobicity, anti-icing performance, and electrical insulating properties of PMIA nanopaper. The modification procedure involves initial CF₄ plasma treatment for 120 s. Subsequently, a suspension of 2 wt% nano-SiO₂ is sprayed to form a composite coating. As a result, the sample exhibits superhydrophobic characteristics with a water contact angle of 158° and a sliding angle below 1°. The anti-icing performance is significantly improved, with water droplet freezing delayed beyond 600 s. Additionally, the surface flashover voltage increased to 17.16 kV, while the volume conductivity is as low as 1.18 × 10^-15 S/m. The increased density of shallow traps on the surface promoted charge dissipation and electric field homogenization.