Abstract:

Gemini imidazolium surfactants 2,4-[C_n-P-C_nim]-1,3-propanediol(Br₂, n=10, 12, 14) were synthesized with dibromoneopenty glycol as the spacer. The surfactants were characterized via ¹H 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), γ_cmc, Γ_max, A_min, pc₂₀ and π_cmc derived from surface tension measurement at 25 ℃ suggest that the surface activities of Br₂ are high. While the thermodynamic parameters of micellization() of all the surfactants derived from electrical conductivity indicate that the formation of micelles is spontaneous and the micellization of [C_n-P-C_nim]Br₂ is entropy-driven.

Key words: Gemini imidazolium surfactant, Surface tension, Electrical conductivity measurement, Critical micelle concentration(cmc), Thermodynamic parameter of micelle formation