A simple route to prepare crack-free thick antireflective silica coatings with improved antireflective stability

In this study, a simple route was proposed to prepare crack-free thick antireflective (AR) silica coatings with improved abrasion resistance and AR stability. Using tetraethylorthosilicate (TEOS) as precursor and hydroxyl-terminated polydimethylsiloxane (PDMS) as modifier, silica AR coatings were prepared by sol-gel process with dip-coating method. It is found that the addition of PDMS extends the adjustable range of sol viscosity, and allows the preparation of thick coatings by a simple route. PDMS prevents the thick AR coating from cracking and enhances its abrasion resistance due to the enhanced particle-to-particle bond strength and the reduced stress inside the film. The hydrophobicity of the coating is also improved by the introduction of hydrophobic methyl groups, and the measured water contact angle increases from 23.4 to 75.3. Thick crack-free AR coatings with good abrasion resistance and antireflective stability can be prepared by this simple route. (C) 2011 Elsevier B.V. All rights reserved.