Fabrication of visible/near-IR antireflective and superhydrophobic coatings from hydrophobically modified hollow silica nanoparticles and poly(methyl methacrylate)

A facile dip-coating approach was developed to fabricate visible/near-IR antireflective and superhydrophobic coatings on glass substrates from hydrophobic hexamethyldisilazane (HMDS)-modified hollow silica nanoparticles (HMDS-HSNs) and poly(methyl methacrylate) (PMMA). While the coated glass substrates showed greatly enhanced transmittance in the visible/near-IR range as compared with uncoated glass substrates, water droplets could roll easily and quickly off the coated surfaces. For the coating prepared using a suspension of 1.00 wt% PMMA and 0.50 wt% HMDS-HSNs, the water contact angle (WCA) of the coating was as high as 163 degrees with a sliding angle (SA) of <= 1 degrees, and the coated glass substrate showed excellent antireflection in the visible/near-IR spectral range with a maximum transmittance of 92.6%. The average transmittance of the coated glass substrate increased to 91.5% as compared to that of the uncoated glass substrate (88.2%) in the spectral range of 573-2500 nm. In particular, in the spectral range of 850-1200 nm, the coated glass substrate (ca. 91%) exhibited an increase of nearly 5% in transmittance as compared with the uncoated glass substrate (ca. 86%). Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used to observe the morphology and structure of the nanoparticles and the coated surfaces. The effects of PMMA and HMDS-HSN concentrations were also discussed on the basis of experimental observations.