Deposition of robust superhydrophobic film with enhanced insulating performance by APTES/O₂ assisted Ar/HMDSO atmospheric pressure plasma jet

The weather resistance capability of insulating materials, i.e. surface performance including hydrophobicity, mechanical and electrical strength under diverse weather conditions, is considered of critical importance for high-voltage devices working outdoors. In this study, atmospheric pressure plasma jet with Ar/Hexamethyldisiloxane (HMDSO) assisted by γ-Aminopropyltriethoxysilane (APTES) and oxygen (O₂) addition is employed to deposit a robust insulating film with good weather resistance capability on the surface of Polymethylmethacrylate (PMMA). The gas flow rates of Si-containing precursors (HMDSO/APTES) and auxiliary gas (O₂) are varied to elucidate the correlation between precursor ratio and film performances. The mechanism for robust film deposition is explored by investigating reactions of active particles deduced from discharge characteristics, surface physical morphology and chemical composition variations. The results indicate that APTES plays a pivotal role in the enhancement of the film mechanical strength, while O₂ can further improve both mechanical and electrical performances. A robust superhydrophobic film is deposited, inhibiting the reduction in water contact angle by 81.6 % after the tape peel test compared with the film deposited by Ar/HMDSO system, and the flashover voltage is increased by 38.2 % with the optimal HMDSO/APTES/O₂ ratio of 7:5:1. The simultaneous improvements of the film hydrophobic, mechanical and electrical performances are contributed by crosslinking of silicone deposits and the introduction of -NH₂ groups. The weather resistance capability of the insulating material is effectively enhanced, providing guidance for outdoor insulation applications.