Fabrication of hydrophobic and antireflective coatings based on hybrid silica films by sol–gel process

This paper reports the synthesis of hydrophobic and antireflective coatings by sol–gel process at room temperature (25 °C), using tetraethylorthosilicate (TEOS) as a precursor and methyltriethoxysilane (MTES), phenyltriethoxysilane (PTES), vinyltriethoxysilane (VTES), and octyltriethoxysilane (OTES) as surface modifying agents. The silica sol was prepared by keeping the molar ratio of TEOS:RTES at 1:1, in acidic conditions with ethanol and 0.1 M HCl. All hybrid systems were enriched with titanium(IV) isopropoxide as the cross-linking agent. It was observed that the obtained silica films become hydrophobic with the introduction of the hydrophobic organic group. The higher value of static water contact angle (107 ± 3°) was obtained for the silica film prepared with TEOS + OTES. Under optimal synthesis condition, we obtained antireflection coatings, exhibiting a low reflection in the visible range.

► The hydrophobic capacity depends on the organic group of precursors. ► A small decrease of reflection in the visible range for all samples was observed. ► The surfaces of the silica films present small hills and valleys.