一种酰胺型Gemini表面活性剂的合成及性能

Synthesis and properties of an amide Gemini surfactant

以十二胺、丙烯酸甲酯、2,6-吡啶二甲酸为主要原料,经过加成、酰胺化、皂化等反应合成了一种酰胺型Gemini表面活性剂N,N’-双十二烷基-2,6-吡啶二酰胺丙酸钠(DLP-12)。经单因素变量考察得出该反应的最佳反应条件为:n(N-十二烷基-β-氨基丙酸甲酯):n(2,6-吡啶二甲酰氯)=2.4:1,40℃下回流反应8h。在此条件下DLP-12的产率为68.14%。性能测定的结果表明,在25,35和45℃时,此种新型Gemini表面活性剂的临界胶束浓度分别为9.1×10^-5,9.5×10^-5和9.7×10^-5mol/L,与之对应的表面张力分别为33.7,32.4和31.1 mN/m,最大表面过剩(Γmax)随着温度的升高而减小,临界堆积参数(CPP)的值表明表面活性剂自组装形态实现由层状结构向棒状结构过渡。25℃时,以液体石蜡和正辛烷作为油相所测得的乳化性能分别为277和252s,罗氏泡沫高度为141 mm。

An amide Gemini surfactant N,N’-bis-dodecyl-2,6-pyridinium dimethylamide propionate sodium(DLP-12)was synthesized from dodecylamine,methyl acrylate,and 2,6-pyridine-dicarboxylic acid by addition,amidation,and saponification reactions.By single factor experiments,the optimum reaction conditions for this reaction were:n(N-dodecyl-β-alanine-methyl ester):n(2,6-pyridine-dicarboxylic acid)=2.4:1,reflux reaction at 40℃for 8 hours.Under these conditions,the yield of the final product was 68.14%.The results showed that the critical micelle concentrations of DLP-12 were 9.1×10^-5,9.5×10^-5 and 9.7×10^-5mol/L at 25,35 and 45℃,respectively,and the corresponding surface tension were 33.7,32.4 and 31.1 mN/m,respectively.The maximum surface excess concentration(Γmax)decreased with the increase of temperature.The value of the critical packing parameter(CPP)indicated the self-assembly morphology of surfactants in aqueous solution transformed from lamellar structure to rod-like structure.At 25℃,the emulsification properties measured with liquid paraffin andn-octane as the oil phase were 277 and 252 s,respectively,and the Roche foam height was 141 mm.