title: Sol-gel preparation of hydrophobic silica antireflective coatings with low refractive index by base/acid two-step catalysis.
abstract: Hydrophobic antireflective coatings with a low refractive index were prepared via a base/acid-catalyzed two-step sol-gel process using tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) as precursors, respectively. The base-catalyzed hydrolysis of TEOS leads to the formation of a sol with spherical silica particles in the first step. In the second step, the acid-catalyzed MTES hydrolysis and condensation occur at the surface of the initial base-catalyzed spherical silica particles, which enlarge the silica particle size from 12.9 to 35.0 nm. By a dip-coating process, this hybrid sol gives an antireflective coating with a refractive index of about 1.15. Moreover, the water contact angles of the resulted coatings increase from 22.4 to 108.7° with the increases of MTES content, which affords the coatings an excellent hydrophobicity. A "core-shell" particle growth mechanism of the hybrid sol was proposed and the relationship between the microstructure of silica sols and the properties of AR coatings was investigated.
authors: Key Laboratory of Green Chemistry & Technology, College of Chemistry, Sichuan University , Chengdu 610064, China.
authors: Shuang
authors: S
authors: Cai
authors: Yulu
authors: Y
authors: Zhang
authors: Hongli
authors: H
authors: Zhang
authors: Hongwei
authors: H
authors: Yan
authors: Haibing
authors: H
authors: Lv
authors: Bo
authors: B
authors: Jiang