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

Recent contact angle studies provide an experimental foundation for theoret ical developments of molecular interactions. These newly obtained contact a ngles are interpreted in terms of combining rules for solid-liquid intermol ecular potential. Results suggest that existing combining rules do not desc ribe adequately the experimental adhesion patterns-the calculated and exper imental patterns differ considerably. It is shown that the combining rule o riginally proposed by Hudson and McCoubrey can be improved to advance our u nderstanding for solid-liquid interactions from like pairs. Macroscopic con tact angle measurements are used to infer relationships of unlike solid-liq uid 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 obta ined from this relation.