Influence of trimethylethoxysilane on the wetting behavior, humidity resistance and transparency of tetraethylorthosilicate based films

Transparent and superhydrophobic films with different adhesion were obtained using trimethylethoxysilane (TMES) as a co-precursor by dip-coating. Silica sol was prepared by keeping the molar ratio of tetraethylorthosilicate (TEOS), ethanol (EtOH), ammonium hydroxide (25%) constant at 1:85.7:8.6, respectively. Along with the increase in molar ratio of TMES/TEOS, the tilt angles of prepared films increased from 2 to 90 degrees. According to the humidity test, the surface roughness is more important in humidity resistance property compared to the chemical compositions; and the films with higher surface roughness showed better humidity resistance. All the films exhibited higher transmittance than the bare substrate in visible light, and better visual transparency was obtained on the films with higher molar ratio of TMES/TEOS. (C) 2013 Elsevier B.V. All rights reserved.