Abstract: Using surface tension method, the changes of surface activity and thermodynamic properties of a novel borate surfactant surfmer (BES) in aqueous solution were studied at different temperatures (288-313 K). The interaction of BES with sodium dodecylbenzene sulfonate (LAS) in 0.5 mol·L-1 aqueous NaCl solutions was also measured. The results showed that the critical micelle concentration(cmc) of BES at 298 K was 0.066 mmol·L-1, and γcmc was 29.2 mN·m-1. The micellization free energie (ΔG0m) was in the range of -22.4 - -25.8 kJ·mol-1 at the experimental temperatures, and the process of micellization of BES was mainly driven by the entropy. The mixed BES/LAS solution was a non-ideal system with negative deviation, and the average molecular interaction parameter βm was -3.48. When the molar fraction αBES of BES in bulk solution was 0.5, its molar fraction X1m in mixed micelles was 0.46, |βm| could reach the maximum, cmc of the mixed solution reached the minimum 0.017 mmol·L-1, and γcmc was 27.8 mN·m-1.

Key words: Surfmer, Borate ester, Critical micelle concentration(cmc), Molecular interaction parameter