通过引进新的溶液制备方法,以光散射、流变、电镜等方法研究了烷烃链长度不对称的阴/阳离子表面活性剂等摩尔混合体系,其中阳离子为二十二烷基三甲基溴化铵(C22TABr),阴离子是烷基羧酸钠(Cn-1COONa, n = 4, 6, 8, 10, 12, 14, 16).结果表明,烷烃链长度高度不对称时(C22/n4)生成了球状胶束,随着降低不对称度,聚集体向棒状、蠕虫状直至囊泡转变.在构成囊泡的体系中,随着降低链长不对称度,聚集体尺寸明显增大.机理分析表明,阴/阳离子对的几何形状决定了聚集体的形貌以及它们的转变.
By introducing a new method of solution preparation, systems of equimolar mixing cationic/anionic surfactants with dissymmetric lengths of alkyl tails were investigated using light scattering, rheology, and freezing-fracture transmission electron microscopy (FF-TEM) measurements, in which the cation was docosyltrimethylammobium bromide (C22TABr) and the anions were sodium alkylcarboxylates (Cn-1COONa, n = 4, 6, 8, 10, 12, 14, 16). The results showed that spherical micelles were favored when the cationic/anionic surfactants had highly dissymmetric length tails (C22/n4). With decreasing dissymmetry of the alkyl tail lengths, the aggregates transformed to rod-like micelles, worm-like micelles, and finally vesicles. In the vesicle-formed cases, the size of the aggregate considerably increased with decreasing dissymmetry of the alkyl tail lengths. By analyzing the mechanism of aggregation, the geometry of the cation/anion pair is thought to determine the morphology and the transition of aggregates