Abstract
The wettability of solids by aqueous solutions of surfactants is very important in many practical applications. Thus, the measured advancing contact angles of aqueous solutions of chosen surfactants on polyethylene (PE) and those taken from the literature on polytetrafluoroethylene (PTFE), poly(methyl methacrylate) (PMMA), and polyamide (nylon 6) were analyzed. Based on the measured values of the contact angles and the literature data of the surface tensions of the studied surfactant solutions, their adsorption at the PE–water interface and the work of adhesion (Wa) were determined. The values of Wa to PE calculated on the basis of the contact angles and surface tensions of these solutions were compared to those determined by applying the new Lifshitz–van der Waals component of the water–PE surface tension. There was a good agreement between the Wa values determined in two different ways. Their contact angles were calculated using the values of PE surface tension, the new Lifshitz–van der Waals component of the water surface tension, and the surface tension of aqueous solutions of the studied surfactants. The contact angle values calculated in such a way were close to the measured values. In the case of PTFE, the same relations were obtained. The values of Wa to PMMA and nylon 6 could be also predicted.
Highlights
The wetting process plays a very important role in many practical applications of surface active agents [1,2,3]
Equation (20) indicates that the slope of this function is equal to −1, which confirms that the adsorption of studied surfactants at the PE–water and water–air interfaces was comparable, and that the surfactant molecules at both interfaces were oriented by the hydrophobic tail toward the hydrophobic phase
The obtained values of the contact angle of aqueous solutions of several anionic, cationic, and nonionic surfactants on PE were measured here, and the contact angles of the aqueous surfactant solutions and their mixtures as well as the mixtures of surfactants in the presence of alcohol on PTFE, poly(methyl methacrylate) (PMMA), and nylon 6 surfaces were taken into account for the analysis of the wetting process in light of components and parameters of the surface tension of polymers, water, and solution
Summary
The wetting process plays a very important role in many practical applications of surface active agents [1,2,3]. The contact angle depends on the change in water’s surface tension under the influence of surfactant, and on the solid surface tension and solid–solution interface tension [2,4]. The changes of the solid surface tension and solid–solution interface tension as a function of the concentration of surfactants in solution can be quite different from those of water surface tension. The packing and orientation of surfactant molecules at the solid–air, solid–solution, and solution–air interfaces influence the work of adhesion of the solution to the solid surface. Wa and θ depend on the components and parameters of the solid and liquid (solution) surface tension [4] Knowing these components and parameters, it should be possible to predict the wettability of some solids by aqueous solutions of the surfactants and their mixtures. In the literature it is difficult to find studies dealing with the possibility of adhesion work and wettability prediction in solid–aqueous solutions of surfactant–air systems
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