Fabrication of Silica-Based Multilayer Films with Self-Cleaning and Antireflective Properties

Abstract

The silica-based multilayer films exhibiting both self-cleaning property and antireflection in the visible and near infrared regions have been deposited onto glass substrate by layer-by-layer deposition of PAH/PAA polyelectrolyte bilayers, followed by sequential deposition of PAH/SiO2 nanocomposite layers to create the nanoporous structure in the film, and finally treating with fluorosilane. To obtain the appropriate porosity and surface roughness so as to satisfy both antireflection and self-cleaning properties, the deposition of PAH/SiO2 nanocomposite layers was varied from 2 to 8 layers. Scanning electron microscopy and atomic force microscopy analysis revealed that a highly nanoporous structure was obtained from the more deposition of loosely agglomerated SiO2 nanoparticles which increased with the increased cycle of PAH/SiO2 deposition. The film consisting of 6 and 8 PAH/SiO2 layers exhibited a very low reflection of only 1-2% in the visible region and approximately 2-4% in the near infrared region, a maximum transmittance of approximately 93% in the visible region and approximately 94% in the near infrared region, and a high advancing contact angle of approximaetly 150 degrees. It is anticipated that the film which exhibited both self-cleaning and antireflection properties enables the application of the antireflection coatings under humid environments.