Preparation of hydrophobic and abrasion-resistant silica antireflective coatings by using a cationic surfactant to regulate surface morphologies

Antireflective (AR) coatings were prepared in the process of the acid catalyzed sol gel process by using tetraethylorthosilicate (TEOS) as silica precursor and cetyltrimethyl ammonium bromide (CTAB) as template. Acid-catalyzed silica AR coatings exhibited extremely strong adhesive forces with glass substrates and excellent abrasion-resistant property. The experimental results revealed that the regulation of the template concentrations in silica sols could not only improve the transmittance of coatings but also alter the surface morphology and roughness. To further improve hydrophobicity and minimize the conflict between roughness and transmittance, the target coating was designed as a bilayer coating, composed of a porous bottom layer acting as AR coating and a rough top layer providing applicable roughness. Trimethylchlorosilane (TMCS) treatment was finally used to obtain the hydrophobicity of the AR coatings. The results indicated that, the antireflection, hydrophobicity and abrasion-resistant property were successfully integrated in the bilayer AR coating, which showed 96.6% transmittance, 130 degrees water contact angle and 5 H pencil hardness. Meanwhile, the multiple performances are very promising in the long practical application of solar collector covers. (C) 2014 Elsevier Ltd. All rights reserved.