Interaction, Surface Activity, and Application of Mixed Systems of Alcohol Ether Sulfate Anionic Surfactants with Multiple Ethylene Oxide Groups and Gemini Quaternary Ammonium Surfactant

The surface activities and application properties for the mixtures of cationic surfactants tetramethylene-1,4-bis[N,N-bis(hydroxypropyl)-hexa/decyloxypropylammonium] bromide (GC₁₀-P) and tetramethylene-1,4-bis[N,N-bis(hydroxyethyl)-hexa/decyloxypropylammonium] bromide (GC₁₀-E) and anionic surfactant isomeric sodium fatty alcohol ether sulfates (iso-AE₉S) were investigated using both the tensiometry and the conductometry. The interaction parameters and thermodynamic micellization parameters of GC₁₀-P/iso-AE₉S and GC₁₀-E/iso-AE₉S mixtures were evaluated by Clint-Rubingh and Motomura theoretical models. When the mole fraction of α₁ for GC₁₀-P/iso-AE₉S mixed system was 0.2, the critical micelle concentration (CMC) reached a minimum of 1.61 × 10^-4 mol/L, and the minimum critical micelle concentration of the GC₁₀-E/iso-AE₉S mixed system is 2.67 × 10^-5 mol/L at α₁ = 0.6. The CMC value of the mixed system is 1-2 orders of magnitude lower than that of any single component. The results indicate that the synergistic effects of the investigated mixed systems (evaluated by β^m) are in order of GC₁₀-P/iso-AE₉S < GC₁₀-E/iso-AE₉S, with maximum β^m values of -17.98 and -9.78, respectively. The change in zeta potential indicates that the poly(ethylene oxide) chain has weakened the charge density of the hydrophilic headgroup of the anionic surfactant. The interfacial tension at the oil-water interface in the mixed system of anionic/cationic surfactants is lower than that of any single component, exhibiting a higher interfacial activity. The mixed system exhibits a decreased contact angle and superior wetting ability over any single component, and it also enhances foam performance, emulsification performance, and degreasing performance.