Wetting of Single and Mixed Surfactant Solutions on Superhydrophobic Surfaces

Abstract

Despite their potential application, the wetting properties of aqueous surfactant solutions on superhydrophobic (SH) solid surfaces have been rarely investigated. In this work single surfactant solutions and binary mixtures of non-ionic and ionic surfactants have been studied in contact with textured and non-textured surface coatings obtained utilizing nanoparticles and a fluorinated polymer. The role of the molecular structure and the concentration in the modification of the wetting properties has been observed both for individual species and mixtures. At supramicellar concentrations a significant decrease in the effectiveness of the mixed solution in wetting the SH surface in comparison to single ionic species has been found. A comparison with the same polymer coating, but in hydrophobic conditions, shows, on the contrary, that the wetting is slightly promoted by the mixture. The molecular size seems to play a positive role in wetting enhancement with the formation of more packed adsorption layer due to molecular penetration. The results of this work should be useful to design surfactant systems for a more effective wetting control.