Strong synergistic effect of cationic hydrocarbon surfactant and novel nonionic tri-block short-chain fluorocarbon surfactant mixtures on surface activity, wettability and solubilization

Mixing hydrocarbon surfactants with fluorocarbon surfactants is still an important strategy to improve the economic benefits and performances of fluorocarbon surfactants and expand their range of application. Herein, we prepared a novel kind of hydrocarbon-fluorocarbon surfactant mixtures via mixing a cationic surfactant, cetyltrimethylammonium bromide (CTAB), with a tri-block nonionic short-chain fluorocarbon surfactant (F9EG13F9) in aqueous solution. The results showed that adding a small CTAB amount to F9EG13F9 (the molar fraction of CTAB in the mixture (x1) was 0.2) could greatly reduce its critical micelle concentrations (cmc) from 0.408 mmol/L to 0.191 mmol/L. At this x1, the contact angle of the mixture was the minimum (57.7 °) at 100 s on polytetrafluoroethylene film, which was even lower than that of F9EG13F9. Besides, CTAB/F9EG13F9 mixtures possessed better colloidal stability and solubilization ability toward hydrophobic dye (Sudan І) than F9EG13F9. The outstanding performances of binary surfactant mixtures benefited from the non-ideal mixing and strong synergistic effect evidence that CTAB/F9EG13F9 surfactant mixtures could be used in practical applications instead of individual F9EG13F9, thereby reducing the used cost of F9EG13F9. Graphical abstract