Calculation of contact angle for hydrophobic powders using heat of immersion data

Heat of immersion (Delta H-im) data are frequently used to investigate the surface characteristics of solids. In this study, the relationship between the heat of immersion and the contact angle is established from first principles for hydrophobic powders. The heat of immersion of three fluorinated carbons in water is obtained by extrapolating the Delta H-im data obtained for dilute mixtures of 1-propanol and water to the point of pure water. The Delta H-im values for pure water are then used to calculate the contact angle associated with the hydrophobic powders.