一种非对称双尾阳离子表面活性剂的合成及表面活性研究

以N,N-二甲基丙二胺、1-溴-十四烷、辛酸等为原料,通过酰化和季铵化反应合成了3个非对称双尾阳离子表面活性剂,用IR和1HNMR表征了中间体和目标产物。酰胺化反应的最佳条件为:投料比n(正辛酸)∶n(N,N-二甲基丙二胺)=1∶1.1,反应温度为120℃,反应时间为10 h。目标产物的最低表面张力(γCMC)均在20～30mN/m,临界胶束浓度(CMC)均在10-5～10-6 mol/L,γCMC和CMC均远低于结构类似单尾表面活性剂的γCMC和CMC。双尾阳离子表面活性剂的泡沫半衰期(T1/2)为22～31 min,泡沫稳定性强于单尾表面活性剂。

Synthesis and Surface Activity of an Asymmetric Twin-tailed Cationic Surfactant

A kind of asymmetric twin-tailed cationic surfactant has been synthesized by acylation and quaternization using N,N-dimethyl propyl diamine,bromote-tradecane and carboxylic acid as the starting materials.The structures of the intermediate products and the title product were characterized by means of IR and 1HNMR.The optimum conditions for acylation were as follows:n(caprylic acid)∶n(N,N-dimethyl propyl diamine)=1∶1.1,temperature of oil bath was 120 ℃ and reaction time was 10 h.The surface tension could decrease to 20～30 mN/m and the critical micelle concentration(CMC) was found to be 10-5～10-6 mol/L,which were all far lower than those of the corresponding traditional quaternary ammonium salt.The foam half time was 22～31 min.The foam of the asymmetric twin-tailed cationic surfactants was more steady than that of the traditional quaternary ammonium salt.