Surface activities and wetting behavior of fluorocarbon-cationic and hydrocarbon-anionic surfactant mixtures in dilute solutions

The surface activities, adsorption properties, and wettability of perfluoropolyether(3) amide propyl dimethyl ammonium iodide (PFPE-A) and sodium lauryl sulfate (K12) mixtures in dilute solutions were investigated by surface tension, dynamic surface tension, and contact angle measurements. The critical micelle concentration (CMC), surface tension at the CMC (γCMC), maximum surface excess concentration (Γmax), and minimum surface area/molecule (Amin) at the air-water interface were evaluated. The wetting abilities of the binary systems on a low-energy surface were also investigated. The experimental results indicated that the PFPE-A/K12 mixture has a good synergistic effect on the surface tension, and even a small amount of PFPE-A could reduce the surface tension of the latter. The higher the PFPE-A content in the mixture, the greater was the rate of surface tension reduction. The wetting performance of the mixtures was poorer than that of PFPE-A. •Synergistic interactions take place in PFPE-A/K12 mixtures.•Adding a small amount of PFPE-A to K12 enhances surface activity.•Negative ∆Gmic values indicate spontaneity of mixed aggregation.