Synthesis and surface activity of mono- and diphosphate ester mixture with different alkyl chain length

ABSTRACT

A series of alkyl phosphate esters were synthesized and each of them was a mixture of monophosphate and diphosphate esters in a high or low mono/dimole ratio. The structure of hexadecyl phosphate ester with a low mono/dimole ratio was confirmed by FTIR, ¹H NMR, and³¹P NMR. The surface tensions of these alkyl phosphate esters were analyzed using a surface tensionmeter. The results showed that the critical micelle concentration (CMC) and critical surface tension (γ_CMC) of phosphate esters with a high mono/di ratio decreased with the increase of alkyl chain length. However, for the phosphate esters with a low mono/di ratio, the CMC, and γ_CMC decreased initially and increased afterwards with the increase of alkyl chain length. Meanwhile, the butanol and octanol phosphate esters with a high mono/di ratio had higher CMC and γ_CMC than their low mono/di ones, while the dodecyl and hexadecyl phosphate esters presented an opposite result. The results indicated that the mono- and diphosphate esters in the mixture may have a synergistic effect on the arrangement of molecules.

GRAPHICAL ABSTRACT

KEYWORDS:

• Alkyl chain length
• mono- and diphosphate ester mixture
• mono/dimole ratio
• surface tension

Additional information

Funding

This work was financially supported by the National High-tech Research and Development Projects (863) (2013AA06A306), the National Natural Science Foundation of China (21474065), and Sichuan Province Leaders in Academic and Technical Training Project Funding (2015/100-5).