Fabrication of robust, transparent PMMA/SiO2 nanocomposite superhydrophobic films with self-cleaning property

Abstract

Optically transparent poly(methyl methacrylate) (PMMA)/ SiO2 nanocomposite superhydrophobic films were fabricated by adip coating method for a small piece of specimen, and a spray-on coating method for a large specimen such as a glass panel. The PMMA molecules were incorporated to improve the film’s robustness and adhesion between the substrate and the film. The coating precursor was prepared by mixing 0.1-0.3 wt.% PMMA with respect to the SiO2 content into 2 wt.% fumed SiO2suspension. The hierarchical surface structure was fabricated by depositing a layer of micrometer-sized SiO2 aggregateobtained from 2.0 wt.% fumed SiO2 suspension followed by a layer of nanometer-sized SiO2 aggregate obtained from 0.5 wt.%fumed SiO2 suspension hydrophobized with trichloro (1H, 1H, 2H, 2H-perfluorooctyl) silane. Under the optimun condition, thedip-coated film exhibited water contact angle (WCA) of 160.4 degrees and transmittance of 95.0%. The spray-coated filmexhibited slightly less WCA of 140.1 degrees and transmittance of 85.0%. The nanocomposite film had good adhesion basedon a peel off test following the ASTM D 3359-02 standard, and good anti-dusting property making it feasible for self-cleaningcoating of glass panel.