The use of interphacial energies to estimate the spreading coefficients of organic liquids by the solid polymer surface of polytetrafluoroethylene

In the article, using equations previously obtained by the author, calculations were made of the interfacial energies of a solid polymer – polytetrafluoroethylene in contact with organic liquids and their vapors. Based on the calculation results, the spreading coefficients in the studied systems were calculated. Since Young’s derivation of the equation for the cosine of the contact angle, many researchers have attempted to determine the surface energy of solids, which would, in turn, make it possible to determine the interfacial energy at the solid-melt (liquid) interface. However, on the way to solving this problem there were obstacles associated with various processes that accompany phenomena occurring on the surface of a solid body in the presence of a liquid (melt) of another body on its surface. This is not the place to list all types of processes. They are well known to specialists in the field of surface phenomena. Here are just a few of them that affect the surface properties of bodies: chemical reactions, mutual dissolution of components of solid and liquid phases, deformation of solid phases, etc. In the case of contact of the polymer with organic liquids, such obstacles do not exist. Also, since it is impossible to dwell on all publications devoted to the determination of the surface energy of solids, the article discusses specific works on determining the interfacial energy at contact angles close to or equal to zero. Since the question of the behavior of interfacial energy at a contact angle equal to zero is of fundamental importance, and there are conflicting opinions in the literature on this matter, giving the correct answer to this question is an urgent task. Using examples of calculations of interfacial energies of homologous series of organic liquids on a solid surface of polytetrafluoroethylene, we have shown that only at zero contact angle the interfacial energy is zero. In this article, using interfacial energy values, we are the first to calculate the spreading coefficients of organic liquids over the surface of a solid polymer, which, in our opinion, is also an urgent task.