title: Water-repellent coatings prepared by modification of ZnO nanoparticles.
abstract: Superhydrophobic coatings with a static water contact angle (WCA)>150° were prepared by modifying ZnO nanoparticles with stearic acid (ZnO@SA). ZnO nanoparticles of size ∼14nm were prepared by solution combustion method. X-ray diffraction (XRD) studies reveal that as prepared ZnO has hexagonal wurtzite structure whereas the modified coatings convert to zinc stearate. Field emission scanning electron micrographs (FE-SEM) show the dual morphology of the coatings exhibiting both particles and flakes. The flakes are highly fluffy in nature with voids and nanopores. Fourier transformed infrared (FTIR) spectrum shows the stearate ion co-ordinates with Zn(2+) in the bidentate form. The surface properties such as surface free energy (γ(p)) and work of adhesion (W) of the unmodified and modified ZnO coatings have been evaluated. The electron paramagnetic resonance (EPR) spectroscopy reveals that surface defects play a major role in the wetting behavior.
authors.affiliation: Surface Engineering Division, CSIR-National Aerospace Laboratories, Bangalore 560017, India. chakra@nal.res.in
authors.forename: R P S
authors.initials: RP
authors.lastname: Chakradhar
authors.forename: V
authors.initials: V
authors.lastname: Dinesh Kumar
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D057927:Hydrophobic and Hydrophilic Interactions; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D011208:Powders; D017550:Spectroscopy, Fourier Transform Infrared; D013229:Stearic Acids / Q000737:chemistry; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D011208:Powders; D013229:Stearic Acids; D014867:Water; C031183:stearic acid; D015034:Zinc Oxide