Studying the Feasibility of Creating Anisotropic Highly Hydrophobic Polymer Surfaces by Ion-Track Technology

Abstract

In the last two decades, the creation and research of superhydrophobic nanomaterials based on the “lotus effect” have attracted great interest. The effect is caused by the heterogeneous wetting of rough surfaces, when the grooves of a rough surface are filled with air (vapour) and water only contacts the tops of the protrusions. The drop forms a sphere on the surface and, if slightly inclined, rolls down and picks up the dirt particles. A wide variety of methods have been developed to produce such materials, among which potential of the ion track technology (ITT) is being explored. The aim of this research was to investigate the wettability of surface microrelief using two materials with different initial hydrophobicity degrees. By modifying the surface of polycarbonate and polypropylene films using the ITT, the samples with water contact angles of 140 ± 5° and 151 ± 5° at maximum, respectively, were obtained. It is shown that such angles are characteristic of microrelief, where the fraction f of the surface that is in contact with the droplet is decreased to the range 0 f 0.3. In order to increase the probability of droplets rolling down the material surface in a certain direction, the materials with inclined microrelief were obtained. In this case, the wettability becomes anisotropic. The droplet loses its spherical shape, deforming in the direction of inclination of needle-like surface elements. It was found that the anisotropy of wettability is higher at an inclination angle of the relief elements of 45° than that at 30° (relative to the flat surface).