Chemical degradation mechanism of methyl-silica superhydrophobic coatings in acidic and alkaline environments

Abstract This study investigates the chemical degradation mechanism of methyl-silica superhydrophobic coatings under acidic (pH 1–3) and alkaline (pH 11–13) conditions. Artificial corrosion tests monitored the evolution of static water contact angle and sliding angle over 360 h. The results indicate that superhydrophobic performance deteriorates significantly with prolonged exposure, with degradation occurring much more rapidly in alkaline environments than in acidic ones. X-ray photoelectron spectroscopy (XPS) analysis reveals a depletion of low-surface-energy methyl groups (-CH 3 ) on the coating surface, leading to increased surface energy. Mechanistically, this chemical change triggers a transition from the Cassie–Baxter to the Wenzel contact mode, increasing the solid–liquid contact area and accelerating the degradation rate. These findings emphasize the critical role of surface chemistry stability and provide theoretical support for optimizing the durability of superhydrophobic coatings in harsh environments.