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

Abstract

In the last two decades, a great interest has been focused on the creation and study of superhydrophobic nanomaterials based on the “lotus effect.” This effect is caused by the heterogeneous wetting of rough surfaces, when the grooves of a rough surface are filled with air (vapor) and water contacts only with the tops of the protrusions. A drop forms a sphere on the surface and rolls down picking up dirt particles when the surface is slightly tilted. Diverse methods have been developed for producing such materials, and the potential of the ion-track technology (ITT) is being investigated. The goal of this work is to study the wettability of surface microtextures by the examples of two materials with different initial degrees of hydrophobicity. The ITT has been employed to obtain samples with maximum water contact angles of 140 ± 5° and 151 ± 5° by modifying the surfaces of polycarbonate and polypropylene films, respectively. It has been shown that such angles are characteristic of microtextures, for which surface fraction f that is in contact with a droplet is decreased to a range of 0 < f < 0.3. Materials with tilted microtextures have been obtained in order to increase the probability of droplet rolling down a material surface in a certain direction. In this case, the wettability becomes anisotropic. A droplet loses its spherical shape and is deformed in the direction of the tilt of needle-like surface elements. It has been found that the anisotropy of wettability is higher at a tilt angle of the texture elements of 45° than that at 30° (relative to the flat surface).