Effect of changing pH and the Ionic Strength on the Surface Forces in Surfactant-Free Thin Aqueous Films
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چکیده
This chapter describes the effect of pH-changes on the surface forces in thin, surfactant-free aqueous films containing a low background concentration of sodium chloride. Despite their exceedingly low surface elasticities, the surfactant-free aqueous films that have an equilibrium thickness about 100 nm are metastable for pH-values between 5 and 10. The extended DLVO theory was used to calculate hydrophobic force constant (K232) from the measured equilibrium film thickness and estimated electrical surface potential. The results suggest that hydrophobic force in surfactant-free foam films is indifferent to pH changes.
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