THE INFLUENCE OF THE SURFACE ACTIVE AGENTS ON WETTABILITY OF LOW ENERGETIC HYDROPHOBIC SOLIDS

摘要

The paper reviews the thermodynamic of the most important problems of wett-ability of a solid and correlation between adsorption of surface active agents at water-air,and solid-water interfaces and wettability of hydrophobic low-energy solids.Three types of wetting have been considered;spreading wetting,adhesional wetting and immersional wetting.The usefulness of the Good and Girifalco,Fowkes,Owens and Wendt,and van Oss et al.approaches to interfacial free energy of liquid--liquid and solid-liquid for determination of work of spreading,immersion and adhesion is presented.The correlation between the work of spreading,immersion and adhesion and contact angle is also shown.On the basis of the contact angle the relationship between wettability of the solids and its surface free energy and surface tension of liquid is discussed.Zisman found for low-energy solids a straight linear relationship between costheta(theta is the contact angle) and surface tension of liquids or aqueous surfactant solutions.The extrapolation of this relationship to costheta=1 allows estimation of the liquid surface tension required to give a contact angle of zero degree,which Zisman described as the critical surface tension.However,in contrary to Zisman,Bergeman and van Voorst Vader,stated that there is straight linear relationship between the adhesional tension (gamma_(LV) costheta) and surface tension,gamma_(LV),of aqueous solutions of several types of surface active agents (surfactants).Such relationship was also confirmed by other investigators,however,the different equations describing the wettability of the same solids than Bergeman and van Voorst Vader by aqueous solutions of surfactants has been suggested.A direct method to investigate relative adsorption at interfaces is described.The usefulness of Lucassen-Reynders equation derived from Young and Gibbs equations for the studies of the correlation between adsorption of the surface active agents at water-air and solid-water interfaces and wettability of low-energy hydrophobic solids is discussed.We proved that on the basis of the surface tension of low-energy hydrophobic solids,surface tension of aqueous solution of surfactants or their mixtures,and Fowkes approach to interfacial tension the wettability of low-energy hydrophobic solids can be predicted.