Environmental effects on transparency and hydrophilicity of silica nano-porous thin film coated glass substrates

Abstract

In this work, silica nano-porous thin films were deposited on glass substrates by a layer-by-layer assembly method. The environmental stability of the thin films was investigated under the salt spray conditions and UV irradiation. XPS, ATR-FTIR, FE-SEM, AFM, UV–Vis spectrophotometer and water contact angle measurements (WCAs) were used to characterize the thin films. The results showed that under the salt spray conditions and UV irradiation, both hydrophilicity and transparency of the thin film were reduced. Under the salt spray conditions at different exposure times of 5, 10, 15 and 20 h, the WCA increased from 3° for silica nano-porous thin film to 13°, 21°, 23° and 26°, respectively, and the transmittance also decreased from the average value of 97% of the thin film to 95.8, 95.3, 95 and 94.7%, respectively. Under the UV irradiation at different times of 5, 20 and 60 days, the WCA increased to 14°, 27° and 30°, and the transmittance also decreased to 95.1, 94.9, and 94%.