Adsorption and thermodynamic properties of dissymmetric gemini imidazolium surfactants with different spacer length

Abstract

<p>A series of dissymmetric gemini imidazolium surfactants with different spacer length ([C_<i>m</i>C_<i>s</i>C_<i>n</i>im]Br₂, <i>m</i> + <i>n</i> = 24, <i>m</i> = 12, 14, 16, 18; <i>s</i> = 2, 4, 6) were synthesized and characterized by ¹H NMR and ESI-MS spectroscopy. Their adsorption and thermodynamic properties were investigated by the surface tension and electrical conductivity methods. Consequently, the surface activity parameters (cmc, γ_cmc, <i>π</i>_cmc, p<i>C</i>₂₀, cmc/<i>C</i>₂₀, <i>Γ</i>_max, <i>A</i>_min) and thermodynamic parameters (Δ<i>G</i>_m^θ, Δ<i>H</i>_m^θ, Δ<i>S</i>_m^θ) were obtained. The effects of the dissymmetry (<i>m</i>/<i>n</i>) and the spacer length (<i>s</i>) on the surface activity and micellization process of surfactants have been discussed in detail.</p