Wetting films on locally heterogeneous surfaces : 1. Hydrophilic surface with hydrophobic inclusions

The problem of the stability of a wetting film covering a hydrophilic surface was solved, and the conditions for the rupture of the film over a small hydrophobic inclusion were found. The critical size of the hydrophobic area was determined, the exceeding of which allows the rupture of the wetting film with the formation of a hole. The dependence of the critical size of the hydrophobic area on the contact angle, which is characteristic of its hydrophobicity, was obtained. To find the solutions, simplified (linear) disjoining pressure isotherms for films on the bydrophilic and hydrophobic surfaces were used. The equations for the profile of the transition zone between the hydrophobic area and the flat wetting film were derived.