Effects of nanorod structure and conformation of fatty acid self-assembled layers on superhydrophobicity of zinc oxide surface

J Colloid Interface Sci. 2007 Dec 15;316(2):233-7. doi: 10.1016/j.jcis.2007.07.046. Epub 2007 Jul 27.

Abstract

Superhydrophobic surfaces have been prepared from nanostructured zinc oxide layers by a treatment with fatty acid molecules. The layers are electrochemically deposited from an oxygenated aqueous zinc chloride solution. The effects of the layer's structure, from a dense film to that of a nanorod array, as well as that of the properties of the fatty acid molecules based on C18 chains are described. A contact angle (CA) as high as 167 degrees is obtained with the nanorod structure and the linear saturated molecule (stearic acid). Lower values are found with molecules having an unsaturated bond on C9, in particular with a cis conformation (140 degrees ). These results, supplemented by infrared spectroscopy, indicate an enhancement of the sensitivity to the properties of the fatty acid molecules (conformation, flexibility, saturated or not) when moving from the flat surface to the nanostructured surface. This is attributed to a specific influence of the structure of the tops of the rods and lateral wall properties on the adsorption and organization of the molecules. CA measurements show a very good stability of the surface in time if stored in an environment protected from UV radiations.

MeSH terms

  • Electrochemistry
  • Fatty Acids / chemistry*
  • Hydrophobic and Hydrophilic Interactions
  • Membranes, Artificial*
  • Molecular Structure
  • Nanotubes / chemistry*
  • Particle Size
  • Surface Properties
  • Zinc Oxide / chemistry*

Substances

  • Fatty Acids
  • Membranes, Artificial
  • Zinc Oxide