Synthesis And Property Study Of Cationic Gemini Surfactant Based On Piperazine

Gemini surfactants achieved extensive attention due to higher efficiency in lowering surface tension, lower critical micelle concentrations(CMC) and superior rheological properties compared to conventional surfactants. In this paper, we focus on the special properties the surfactants displayed and use the materials which is easy to obtained to synthesize a series of new Gemini surfactants using simple techniques.In this dissertation, a series of cationic Gemini surfactants Cn-pi-Cn(n=18, 16, 12)were synthesized from piperazine, epichlorohydrin, octadecyl dimethyl amine, hexadecyl dimethyl amine and dodecyl dimethyl amine using two-step method. The chemical structures of the prepared compounds were confirmed by IR, MS and1 H NMR, and the best synthetic route and process were explored. Based on the synthetic compounds, we focused on the effect of the steric hindrance on the surface properties of the Gemini surfactant which bearing piperazine moiety as spacer.The bromophenol blue experiment was used to demonstrate the cationic of the targeted Gemini surfactants, for it can change color from red to violet. Their surface activities were evaluated by surface tension, electrical conductivity and steady-state fluorescence. The results indicated that the synthesized Gemini surfactants exhibited lower surface tension(γcmc) and critical micelle concentration(CMC) compared with traditional surfactants. Compared with Gemini surfactant 12-2-12 which based on a spacer present lower steric effect, C12-pi-C12 showed a lower CMC. It was found that among the synthetic Gemini surfactants Cn-pi-Cn(n=18,16,12), CMC showed a decreased tendency following the increase of the carbon chain. In addition, the electrical conductivity experiment and the steady-state fluorescence measurement showed similar CMC values to surface tension experiment. The micellization behavior was evaluated using conductivity measurement in the temperature range of 298 K-308 K.The foamability and foam stability of these Gemini surfactants were also examined.In which, the Gemini surfactant with the shortest chain(C12) showed the best foamability but the poorest foam stability. The HLB results showed a decreased tendency following the increase of the carbon chain. The emulsifying ability were studied and a comparatively poor emulsifying ability displayed. The emulsified asphalt experiment also present a poorresult.