Synthesis and Surface Properties of Novel Gemini Imidazolium Surfactants

Gemini imidazolium surfactants 2,4-[bis(3-alkylimidazolium-1-yl)bromide]-1,3-propanediol ([C-n-P-C(n)im]Br-2, n=10, 12, 14) were synthesized with dibromoneopenty glycol as the spacer. The surfactants were characterized via H-1 NMR spectra, IR spectra and elemental analysis, and the results prove that they are all the objective products. The surface activity and thermodynamic properties of micellization of the surfactants were characterized by surface tension and electrical conductivity measurements. The values of critical micelle concentration(cmc), gamma(cmc), Gamma(max), A(min), pc(20) and pi(cmc) derived from surface tension measurement at 25 degrees C suggest that the surface activities of [C-n-P-C(n)im]Br-2 are high. While the thermodynamic parameters of micellization(Delta G(m)((sic)), Delta H-m((sic)), Delta S-m((sic))) of all the surfactants derived from electrical conductivity indicate that the formation of micelles is spontaneous and the micellization of [C-n-P-C(n)im]Br-2 is entropy-driven.