Wetting and Adsorption Properties of Aqueous Solutions of Ternary Mixtures of Hydrocarbon and Fluorocarbon Nonionic Surfactants in PTFE-Solution-Air Systems

The surface tensions and contact angles of aqueous solutions of ternary mixtures of hydrocarbon, TX100 and TX165, and fluorocarbon, FSN100, surfactants at different mole fractions in the bulk phase on a poly(tetrafluoroethylene) (PTFE) surface were studied. The measured values were used in the Young equation for calculations of the polymer-solution interfacial tension in two ways, first, assuming that the surface tension of PTFE is constant and, second, assuming that this tension is not constant and is equal to the value determined for FSN100 at a given concentration. Next, the Gibbs surface excess concentrations of the studied mixtures at the polymer-solution interface were calculated and compared to the corresponding values at the solution-air interface. Also, the critical surface tension of polymer wetting was obtained from the relationship between the adhesion tension and the surface tension of aqueous solutions of the studied mixtures and then related to the adsorption of the surfactants at the water-air and PTFE-water interfaces.