Contact angle interpretation: Combining rule for solid-liquid intermolecular potential

Recent contact angle studies provide an experimental foundation for theoretical developments of molecular interactions. These newly obtained contact angles are interpreted in terms of combining rules for solid-liquid intermolecular potential. Results suggest that existing combining rules do not describe adequately the experimental adhesion patterns-the calculated and experimental patterns differ considerably. It is shown that the combining rule originally proposed by Hudson and McCoubrey can be improved to advance our understanding for solid-liquid interactions from like pairs. Macroscopic contact angle measurements are used to infer relationships of unlike solid-liquid interactions at a molecular level. The resulting combining rule gives a good fit to experimental adhesion and contact angle patterns for the range studied. The thermodynamic property solid surface tension can also be obtained from this relation.