关键词: 季铵盐Gemini表面活性剂, 动态表面张力, 最大泡压法

Adsorption kinetics of Gemini surfactant C₁₂-2-E_x-C₁₂?2Br (x＝1, 2, 3) at the water-air interface was studied by maximum bubble pressure technique. The kinetics effect of adsorption was enhanced when the bulk concentration or the temperature was increased because the surfactant molecules moved faster from the bulk to the surface. Since the molecules with short spacer chains were easy to pre-aggregate as compared with those with long spacers, the concentration of mono molecules of the latter in the bulk was higher than that of the former, which promoted the diffusion of the former molecules to the surface in the short time and decreased the γ_t more quickly. However, in the long time as the surface was nearly completely covered, the γ_m of surfactant with long spacer was high because this kind of molecules occupied large surface areas resulting in less endmost methyls of them protruding into the air. Compared with the conventional surfactant C₁₂TABr which had the same kind of head group and the same length of hydrophobic chain as C₁₂-2-E_x-C₁₂?2Br, the latter seemed more favorable to adsorb at the surface than the former.

Key words: Gemini surfactant, dynamic surface tension, maximum bubble pressure technique