A simple strategy to improve surface activity and wettability of anionic hydrocarbon and tri-block nonionic short-chain fluorocarbon surfactant mixtures

Abstract

To address the problem that the surface activity of reported hydrocarbon-fluorocarbon (CH-CF) surfactant mixtures was usually difficult to reach the level of corresponding CF surfactant, we reported a simple strategy that is utilizing the electrostatic screen effect of inorganic cation (Na+) on anionic surfactant to control the interfacial arrangement of anionic-nonionic mixed surfactants and improve the surface activity and wettability of novel CH-CF surfactant mixtures constituted with an anionic surfactant, sodium dodecylbenzene sulfonate (SDBS), and a tri-block nonionic short-chain fluorocarbon surfactant (F9EG13F9). The results showed that at 0.25 mol/L NaCl, the surface activity of surfactant mixture was on a par with that of individual F9EG13F9 (21.4 mN/m) when the molar fraction of SDBS in the mixture (x1) was 0.6, and its cmc value (0.154 mmol/L) was less than individual F9EG13F9 (0.408 mmol/L). At this x1, the contact angle had the minimum value (70.2°) on polytetrafluoroethylene film. The findings mentioned above probe that the SDBS/F9EG13F9 surfactant mixture with a specific proportion is a potential alternative for individual F9EG13F9 at appropriate NaCl content, which can effectively reduce the used cost of F9EG13F9 without reducing its surface activity and wettability.