Durable silica antireflective coating prepared by combined treatment of ammonia and KH570 vapor

Sol–gel silica antireflective (AR) coatings possess a high specific surface area that is more susceptible to be contaminated by absorption of contaminants from the environment, which will increase the refractive index and reduce the transmittance. Ammonia and γ-methacryloxypropyltrimethoxysilane (KH570) vapor treatment was employed to passivate the silica AR coating, thereby enhancing the environmental stability. The properties of the coatings were characterized with Fourier transfer infrared absorption spectroscopy, scanning electron microscopy, atomic force microscopy, UV–Vis–NIR spectrometer, and contact angle measurement. The results showed that after the vapor treatment, the coatings became denser and the environmental stability was greatly improved. After being exposed to a humid environment (RH > 90%) and low-vacuum environment with intentionally induced organic contaminants for 60 days, the transmittance of the modified SiO2 coating decreased by only 0.08% and 0.2%, respectively. Meanwhile, the average transmittance decreased by only 0.02% after being rubbed for 1000 cycles, indicating that the co-treated coating also possessed a good abrasion resistance.