Silica nanoparticles synthesized from tetraethoxysiliane (TEOS) via a sol-gel process were surface-modified by using 3-(trimethoxysilyl)propyl methacrylate (MSMA) and 1H, 1H, 2H, 2H- perfluorooctyltriethoxysilane (13F). MSMA acted as a coupling agent and a C=C provider, whereas 13F was employed to enhance hydrophobicity. The surface-modified silica particles together with a multi-functional monomer were UV-cured to yield highly transparent thin films (~7 μm) on plastic substrates. Both FE-SEM imaging and UV-visible spectroscopy confirmed uniform dispersion of nano-silica in the hybrid thin films. The coating surfaces were extremely smooth, with average roughness over the range 1.0-2.3 nm based on profilometric measurements. X-ray photoelectron spectroscopy indicated that surface-modified silica particles have migrated to the top surface to reduce the surface energy. Therefore, only a small dosage of 1 mol% (vs. TEOS) was enough to engender surface hydrophobicity with water contact angle of 100°. Furthermore, all of the prepared coatings were hard with pencil hardness reached 6H, and they adhered strongly to the poly(methyl methacrylate) substrate according to the peel test.
Journal of applied science and engineering 18(4), pp.387-394