Principles of design of superhydrophobic coatings by deposition from dispersions

The analysis demonstrating the abilities of various types of ordered textures, constructed from spherical particles, to provide high water contact angles on the surface of the hydrophobic material is presented. For several ordered three-dimensional surface structures we have derived the equations, relating the contact angles, formed by water droplets on a textured coating, with the geometric parameters of the texture and the chemical properties of the coating. The conditions providing the thermodynamic stability of heterogeneous wetting regime on textured surfaces have been discussed. It was demonstrated that multimodal surface roughness facilitates essentially the attainment of the superhydrophobic state and the surface textures exhibiting the stable superhydrophobic properties may be effectively manufactured by controlled aggregation of particles. Based on the analysis of forces acting between the nanoparticles both in the bulk dispersions and in the deposited film, we discuss the correlation of the properties of dispersion with the surface textures formed.