Preparation of high-hardness silicon-based antireflective optical coatings at low temperature and without calcination

Mechanical strength is an important factor that affects and limits the life of surface antireflective (ARC) coatings such as optical lenses, photovoltaic panels, and liquid crystal displays. In this work, a network-structured silica sol was prepared using tetraethyl orthosilicate (TEOS) and methyltriethoxysilane as silicon sources. Triethoxy(1H,1H,2H,2H-nonafluorohexyl)silane (C₄FTES) was used to modify the acid-catalyzed silica sol. Finally, the mixed sol was plated on the surface of polymethyl methacrylate by impregnation-pulling method. The coating obtained after drying at 100°C showed a maximum transmittance of 97.98% in the visible wavelength range (400–800 nm). The coating still maintained good optical properties after undergoing various wear-resistant tests such as sandpaper abrasion and cotton ball friction. Moreover, the pencil hardness test of the coating improved from 5B to 3H after it was modified by short-chain perfluoroalkyl groups (C₄FTES). This work required only low-temperature treatment without calcination to prepare a silicon-based ARC coating formed by copolymerization of C₄FTES and TEOS, and the mechanical properties of the coating meet actual needs. This easy-to-operate preparation method greatly expands the application scope of silicon-based ARC coatings in the field of heat-sensitive materials.

Graphical abstract

The polymethyl methacrylate (PMMA) substrate is coated with a fluorine-containing coating with a network structure, which greatly improves the transmittance and surface hardness of the substrate.