The molecular origin of contact angles in terms of different combining rules for intermolecular potentials

Knowledge of interfacial free energy is necessary for a better understanding and modeling of interfacial processes such as wetting, spreading and floatation. However, direct measurement of the solid-vapor (ysv) and solid-liquid (ysl) interfacial tensions is not available. Among the different indirect approaches in determining solid surface tensions, contact angle is believed to be the simplest and hence widely used approach [1, 2].