title: Superhydrophobic films on glass surface derived from trimethylsilanized silica gel nanoparticles.
abstract: The paper deals with the fabrication of sol-gel-derived superhydrophobic films on glass based on the macroscopic silica network with surface modification. The fabricated transparent films were composed of a hybrid -Si(CH(3))(3)-functionalized SiO(2) nanospheres exhibiting the desired micro/nanostructure, water repellency, and antireflection (AR) property. The wavelength selective AR property can be tuned by controlling the physical thickness of the films. Small-angle X-ray scattering (SAXS) studies revealed the existence of SiO(2) nanoparticles of average size ∼9.4 nm in the sols. TEM studies showed presence of interconnected SiO(2) NPs of ∼10 nm in size. The films were formed with uniformly packed SiO(2) aggregates as observed by FESEM of film surface. FTIR of the films confirmed presence of glasslike Si-O-Si bonding and methyl functionalization. The hydrophobicity of the surface was depended on the thickness of the deposited films. A critical film thickness (>115 nm) was necessary to obtain the air push effect for superhydrophobicity. Trimethylsilyl functionalization of SiO(2) and the surface roughness (rms ≈30 nm as observed by AFM) of the films were also contributed toward the high water contact angle (WCA). The coated glass surface showed WCA value of the droplet as high as 168 ± 3° with 6 μL of water. These superhydrophobic films were found to be stable up to about 230-240 °C as confirmed by TG/DTA studies, and WCA measurements of the films with respect to the heat-treatment temperatures. These high water repellant films can be deposited on relatively large glass surfaces to remove water droplets immediately without any mechanical assistance.
authors.affiliation: Nano-Structured Materials Division, Central Glass and Ceramic Research Institute, Council of Scientific and Industrial Research, 196 Raja S. C. Mullick Road, Kolkata 700032, India.
authors.forename: Debmita
authors.initials: D
authors.lastname: Goswami
authors.forename: Samar Kumar
authors.initials: SK
authors.lastname: Medda
authors.forename: Goutam
authors.initials: G
authors.lastname: De
mesh_terms: D005898:Glass / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D053838:Scattering, Small Angle; D012821:Silanes / Q000737:chemistry*; D058428:Silica Gel / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D012821:Silanes; D014867:Water; D058428:Silica Gel; D012822:Silicon Dioxide