UV resistance of sol-gel hydrophobic silica antireflective coatings

• Published in: Journal of sol-gel science and technology Vol. 106; no. 2; pp. 381 - 392
• Main Authors: Su, Yixuan, Wang, Xiaodong, Zhao, Huiyue, Zhang, Chen, Yuan, Fang, Guo, Jingwen, Feng, Chen, Shen, Jun
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.05.2023; Springer Nature B.V
• Subjects: Antireflection coatings; Bond energy; Ceramics; Chemical composition; Chemistry and Materials Science; Composites; Contact angle; Fluorine; Free energy; Glass; Hydrophobicity; Inorganic Chemistry; Irradiation; Materials Science; Nanoparticles; Nanotechnology; Natural Materials; Optical and Electronic Materials; Optical properties; Original Paper: Functional coatings; Radiation tolerance; Silanes; Silica gel; Silicon dioxide; Sol-gel processes; Sol-Gel Research in China; Surface properties; thin films and membranes (including deposition techniques); Ultraviolet radiation; Wettability; UV resistance; Surface free energy; Antireflective coating
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-022-05729-9

Hydrophobic surface with satisfactory resistance to ultraviolet (UV) radiation plays a vital role in sol–gel porous antireflective (AR) coatings. In this work, sol–gel hydrophobic silica AR coatings were prepared by modifying the surface of nanoparticles with fluorine-free organosilanes (hexamethyldisilazane, hexadecyltrimethoxysilane, and N-octyltrimethoxysilane) or fluorine-containing silanes (1H, 1H, 2H, 2H-perfluoroalkyltriethoxysilane and 1H, 1H, 2H, 2H-perfluorooctyltrichlorosilane). The UV resistance of the coatings grafted with different hydrophobic groups was studied through monitoring the changes in wettability and optical properties of the coatings before and after UV irradiation. In addition, the evolution in the surface characteristics of the coatings after UV irradiation was evaluated by studying their surface morphology and chemical composition. Based on the contact angle results, the surface free energy (SFE) of the coatings before and after UV irradiation was estimated and compared. After UV irradiation, the SFE of fluorine-free organosilane-modified silica coatings increases dramatically, whereas the coatings modified with the fluoroalkyl silanes still maintain very low SFE. The high bond energy of C−F provides a particularly high degree of resistance to UV light damage, which imparts the long-chain fluoroalkyl-grafted POTS/SiO 2 and POTCS/SiO 2 coatings with superior UV resistance. The fluorine-containing organosilane modification provides an effective way to simultaneously integrate high transparency and excellent UV resistance for hydrophobic silica coatings. Graphical abstract Highlights The UV resistance of different hydrophobic silica antireflective coatings was studied. The fluorine-containing organosilane-modified silica coating exhibits combined advantages of high transparency, UV resistance, and hydrophobicity. The surface of fluorine-free organosilane-modified silica coating changes from hydrophobic to super-hydrophilic.