季铵盐型Gemini 表面活性剂水溶液的表面和油-水界面特性

 用 DCAT-21型表面张力及接触角仪测定了不同结构的季铵盐型 Gemini 表面活性剂 C_n-s-C_n·2Br 溶液的表面张力和界面张力变化，为选择一种较好的表面活性剂作为驱油剂提供基础。结果表明，烷基链长n 均为12时，随联接基团数s 的增加，季铵盐型 Gemini 表面活性剂降低表面和界面张力能力减小。s 相同时，随着烷基链长n 增加，Gemini 表面活性剂的临界胶束浓度（CMC）减小。加入无机盐可以进一步降低 Gemini 表面活性剂的 CMC 值。季铵盐型 Gemini 表面活性剂的 CMC 值较类似结构的单链单头普通表面活性剂的 CMC 值低，且达到最低界面张力时的浓度比单链单头普通表面活性剂低2个数量级。Gemini表面活性剂的高表面活性主要由其特殊的分子结构所决定。

Interfacial Properties of Quaternary Ammonium Gemini Surfactants in Aqueous Solutions

Interfacial properties of quaternary ammonium Gemini surfactants in aqueous solution were studied due to their special excellent surface activity in surfactant flooding system. DCAT-21 surface tension meter were adopted to determine the variation of surface tension and interfacial tension of different molecular structures of C_n-s-C_n·2Br in aqueous solution. Effect of mineral salt on the surface activity of Gemini surfactants aqueous solutions were investigated as well. Experiments indicated that the surface and interfacial tension reduction of C_n-s-C_n·2Br aqueous solution decreased as the length of spacer(s) increased while the length of alkyl chain(n) was 12. Critical micelle concentration (CMC) of quaternary ammonium Gemini surfactants decreased as the length of alkyl chain(n) increased. Their CMC were much lower (about 2 orders of magnitude) than that of corresponding common surfactants, and could be lowered by mineral salt. The outstanding surface activity of Gemini surfactants was owing to their unique molecular structure.