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本文总结了Gemini表面活性剂分子结构中联接链在其自组织过程中所发挥的独特作用,这主要来自联接链长度和刚柔性两方面的效应,这些效应综合导致了Gemini分子两条烷烃尾链的协同作用、头基电荷密度改变、分子几何变化以及由此决定的多样化聚集体结构及形貌等。更具体地讲,柔性联接链主要依赖不同长度影响分子的上述功能。过长的联接链还可能通过自身弯曲来适应环境,从而影响分子自组织。短刚性联接链的效应等同于类似长度的柔性联接链,而长刚性联接链由于阻碍了两条烷烃尾链的靠拢,产生了两个突出特征:分子呈似柱形状以及同等几率的两条尾链沿联接链顺式或反式排列构型。这使得长刚性联接链分子在低浓度时就可形成网状聚集体,增加浓度或少量添加剂干扰易转变成低表面曲率的线状胶束或囊泡。适合条件还可催生少量反式构型分子,它们将一条烷烃尾链伸出聚集体外,通过疏水相互作用串接相邻的聚集体。本文也讨论了对联接链进行的化学修饰,这有望促进分子的自组织活性,或者赋予聚集体某种新的特殊功能。列举的例子很好表明了Gemini分子结构的独特性,以及Gemini表面活性剂复杂的自组织行为和多样化的聚集结构。
This article summarizes the unique role Gemini surfactants play in their self-organization in the molecular structure of the Gemini surfactant. This is mainly due to the effect of the length of the linker chain and the flexibility of the Gemini surfactant. These effects result in two Gemini molecules, Synergy, changes in head charge density, molecular geometry, and the diversity of aggregate structures and topographies determined thereby. More specifically, flexible linking chains rely primarily on different lengths affecting the above functions of a molecule. Long links may also adapt to the environment by bending themselves, thus affecting the molecular self-organization. The effect of short rigid linkages is equivalent to that of flexible linkages of similar length, whereas the long rigid linkages result in two salient features due to obstructing the closing of the two paraffin tail chains: the molecules are column-like and have two tails of equal probability The chains are arranged in cis or trans arrangement along the linking chain. This allows long rigid linker molecules to form reticular aggregates at low concentrations, with increasing concentrations or small amounts of additives interferes with linear micelles or vesicles that readily convert to low surface curvature. Suitable conditions can also generate small amounts of trans-configuration molecules, which extend a paraffin tail chain out of the aggregate, bridging adjacent aggregates by hydrophobic interactions. This article also discusses the chemical modification of the linker chain, which is expected to promote the self-organization of the molecule or to give the aggregate some new, specialized function. The examples presented illustrate the uniqueness of Gemini’s molecular structure and the complex self-organizing behavior of Gemini surfactants and their diverse aggregated structures.