A 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. T...
