Wetting Criteria Zismans Rule

Is it possible to predict whether a solid surface is wettable Fortunately, the answer is yes. Surfaces belong in one of two categories  

Low-energy (LE) surfaces, for which the chemical binding energy is of the order of kT, which are generally hardly wettable. They include molecular crystals and plastics. In this case, we have 

Actually, the surface energy 750 in contact with air is not altogether sufficient to predict wettability. What is in fact needed is the sign of the spreading parameter S given by 

We shall now restrict our attention to an idealized (but important) case—-the interactions (liquid-liquid and liquid-solid) are purely of the van der Waals type. It is then possible to relate S to the electric polarisabilites of S and 

To estimate Jsl, one brings the solid and the liquid together. One starts with an energy 7 + 750, and one picks up the van der Waals interactions VsL between the solid and the liquid (as before, we have Vsl = /c so l)-This leads to 

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