la3008156_si_001.pdf (2.56 MB)
pH-Responsive Surface Activity and Solubilization with Novel Pyrrolidone-Based Gemini Surfactants
journal contribution
posted on 2012-05-08, 00:00 authored by Zan Jiang, Xuefeng Li, Guangfu Yang, Li Cheng, Bo Cai, Yi Yang, Jinfeng DongA new series of pH-responsive Gemini surfactants with
2-pyrrolidone
head groups, N,N′-dialkyl-N,N′-di(ethyl-2-pyrrolidone)ethylenediamine
(Di-CnP, where n = 6,
8 10, 12), were synthesized and characterized by 1H NMR, 13C NMR, ESI-MS, and elemental analysis. The surface activity
and micellization behavior at acidic, neutral, and basic conditions
were characterized by equilibrium surface tension and fluorescence
techniques. It was found that the surface activity of Di-CnP depends on the pH of aqueous solutions due to the
protonation state of surfactant molecules when pH was varied. The
new compounds have lower cmc and γcmc in comparison
with that of m-2-m type conventional
cationic Gemini surfactants and gluconamide-type nonionic Gemini surfactants.
Fluorescence data confirm that micelles are formed when the concentration
is above the cmc. Since micellization is of fundamental importance
in surfactant applications such as solubilization, microemulsion,
and related technologies, the significant difference in cmc at different
pH of this new Gemini surfactant is employed to solubilize cyclohexane.
The preliminary result indeed shows that the solubilization capacity
of Di-CnP can be tuned by pH.