Fabrication of superhydrophobic surfaces based on ZnO–PDMS nanocomposite coatings and study of its wetting behaviour

• Published in: Applied surface science 2011-08, Vol.257 (20), p.8569-8575
• Main Authors: Chakradhar, R.P.S., Kumar, V. Dinesh, Rao, J.L., Basu, Bharathibai J.
• Format: Article
• Language: English
• Subjects: Clusters, nanoparticles, and nanocrystalline materials; Coatings; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Contact angle; Cross-disciplinary physics: materials science; rheology; Electron paramagnetic resonance (EPR); Exact sciences and technology; FESEM; Free energy; FTIR; Materials science; Nanocomposites; Nanomaterials; Nanoscale materials and structures: fabrication and characterization; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Nanostructure; Other topics in nanoscale materials and structures; Physics; Raw materials; Sliding angle (SA); Solid-fluid interfaces; Solvents; Structure of solids and liquids; crystallography; Superhydrophobic; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Water contact angle (WCA); Wetting; XRD; Zinc oxide; ZnO–PDMS nanocomposite coating
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2011.05.016

► Superhydrophobic (SH) surfaces based on ZnO–PDMS nanocomposite coatings are demonstrated by wet chemical method. ZnO coating exhibits wetting behaviour with WCA of ∼108°, on modification with PDMS, it transforms to superhydrophobic surface ∼155°. ► FESEM micrographs reveal that nanoparticles are connected to each other to make large network systems consisting of hierarchical structure. ► EPR studies on SH coatings revealed that the surface defects play a major role on the wetting behaviour. Advantages of the present method include the cheap and fluorine-free raw materials, environmentally benign solvents, and feasibility for applying on large area of different substrates. Superhydrophobic surfaces based on ZnO–PDMS nanocomposite coatings are demonstrated by a simple, facile, time-saving, wet chemical route. ZnO nanopowders with average particle size of 14 nm were synthesized by a low temperature solution combustion method. Powder X-ray diffraction results confirm that the nanopowders exhibit hexagonal wurtzite structure and belong to space group P63 mc. Field emission scanning electron micrographs reveal that the nanoparticles are connected to each other to make large network systems consisting of hierarchical structure. The as formed ZnO coating exhibits wetting behaviour with Water Contact Angle (WCA) of ∼108°, however on modification with polydimethylsiloxane (PDMS), it transforms to superhydrophobic surface with measured contact and sliding angles for water at 155° and less than 5° respectively. The surface properties such as surface free energy ( γ p), interfacial free energy ( γ pw), and the adhesive work ( W pw) were evaluated. Electron paramagnetic resonance (EPR) studies on superhydrophobic coatings revealed that the surface defects play a major role on the wetting behaviour. Advantages of the present method include the cheap and fluorine-free raw materials, environmentally benign solvents, and feasibility for applying on large area of different substrates.