The morphology of micelles formed by three sub-classes of metallosurfactantsâthose with macrocyclic, linear and gemini head groupsâhas been studied by small-angle neutron scattering (SANS) for a series of metal- and counter-ions. All the data may be described by a model that invokes a globular micelle morphology in which the dimensions of the micelle are consistent with the known chemical structure of the constituent groups within the metallosurfactant. For two macrocyclic head group metallosurfactants, viz. 1-(2-hydroxy-tetradecyl)-1,4,7-triazacyclonane that forms predominantly spherical micelles and 1-(2-hydroxy-tetradecyl)-1,4,7,10-tetraazacyclononane that forms disc-like micelles, the metal ion and its counter-ion have a negligible effect on the morphology of the micelle. Binary mixtures of surfactants with these two macrocyclic head groups (with homo- or hetero-metal ions/counter-ions) form mixed micelles whose morphology is an average of the two single component micelles. Further, as found for the single surfactant solutions, the metal and counter-ion had no effect on the morphology of the mixed surfactant micelle. Lastly, the micelle morphology of two gemini surfactants was also shown to be insensitive to the number and nature of the metal and counter-ions present, but sensitive to the structure of the head group. These observations considerably extend our understanding of the relationship between chemical structure and micelle morphology for these interesting molecules.
我们通过小角中子散射(
SANS)技术研究了一系列
金属离子和反离子的三个亚类
金属表面活性剂(具有大环、线性和双子头基团的
金属表面活性剂)形成的胶束形态。所有数据都可以用一个球状胶束形态模型来描述,其中胶束的尺寸与
金属表面活性剂中组成基团的已知
化学结构一致。对于两种大环头基
金属表面活性剂,即主要形成球形胶束的 1-(2-羟基-
十四烷基)-
1,4,7-三氮杂环壬烷和形成盘状胶束的 1-(2-羟基-
十四烷基)-1,4,7,10-四氮杂
环壬烷,
金属离子及其反离子对胶束形态的影响微乎其微。具有这两种大环头基团(具有同种或异种
金属离子/反离子)的表面活性剂的二元混合物会形成混合胶束,其形态是两种单组分胶束的平均形态。此外,与单一表面活性剂溶液一样,
金属和反离子对混合表面活性剂胶束的形态没有影响。最后,两种双子表面活性剂的胶束形态也被证明对存在的
金属和反离子的数量和性质不敏感,但对头部基团的结构敏感。这些观察结果大大扩展了我们对这些有趣分子的
化学结构与胶束形态之间关系的理解。