关键词: 双子表面活性剂, 硫酸酯间隔基, 表面张力, 界面张力, 抗菌活性

Abstract:

Gemini surfactants, in which the two hydrophilic headgroups are linked by a spacer nearby, have unique properties that arise from their particular molecular structure. The spacer group therein is important and indispensable in the molecular structure of gemini surfactants. A large number of studies so far have been devoted to the effects of different spacers, but sulfate-containing spacers are rarely reported. In this work, a series of sulfate-spacered gemini surfactants with different degrees of sulfonation （14-xSO₄-14） were synthesized from 14-OH-14 by sulfonation using different amount of chlorosulfonic acid. The molecular structure was characterized using ¹H NMR and electrospray ionization mass spectroscopy （ESI-MS）, and the degree of sulfonation was measured using inductively coupled plasma-optical emission spectrometry （ICP-OES）. The results showed that, compared with unsulfonated 14-OH-14, the cmc of 14-xSO₄-14 gradually decreased with increasing degree of sulfonation, and a minimum was obtained at x=1.0 （decreasing the cmc by one order of magnitude）. Furthermore, 14-xSO₄-14 exhibited greater abilities to self-assemble and to reduce surface/interfacial tension. 14-xSO₄-14 could not only reduce the oil-water interfacial tension to an ultra-low level, but also maintain it for a wide time window. Among these geminis with different degrees of sulfonation, 14-0.2SO₄-14 exhibited the best foaming ability and foam stability and the best antimicrobial effect against E. coli, while 14-0.6SO₄-14 had the best antimicrobial effect against S. aureus.

Key words: gemini surfactant, sulfate-containing spacer, surface tension, interfacial tension, antimicrobial activity