Preparation of antireflective coatings with high transmittance and enhanced abrasion-resistance by a base/acid two-step catalyzed sol–gel process

Abstract

Antireflective (AR) coatings with high transmittance and enhanced abrasion-resistance were prepared by a base/acid two-step catalyzed sol–gel process using tetraethylorthosilicate (TEOS) as precursor. These AR coatings exhibit both high transmittance and enhanced abrasion-resistance when the mole ratio of acid-catalyzed silica to base-catalyzed silica was 0.5. The experimental results revealed that the acid-catalyzed silica was covalently bonded to base-catalyzed silica particles, which greatly increased the abrasion-resistance. Hexamethyldisiloxane (HMDS) treatment was further used to improve the hydrophobicity of the AR coatings. The water contact angles of pure silica AR coatings and AR coatings treated with 16% HMDS were 21.3° and 72.5°, respectively, indicating a significant increase in hydrophobicity. FTIR spectra revealed the existence of –Si (CH 3) 3 after HMDS treatment, showing that the hydroxyl groups of AR coatings were replaced by –OSi (CH 3) 3, affording the AR coatings treated with HMDS excellent environmental resistance.