GEMINI SURFACTANTS - A NEW CLASS OF SELF-ASSEMBLING MOLECULES
GEMINI SURFACTANTS - A NEW CLASS OF SELF-ASSEMBLING MOLECULES
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DOI：
10.1021/ja00075a025
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发表时间：
1993-11-03
影响因子：
15
通讯作者：
LITTAU, CA
中科院分区：
文献类型：
--
作者：
MENGER, FM;LITTAU, CA
“双子表面活性剂”是一个名称分配给一个家庭的合成两亲物拥有，在顺序，一个长的烃链，一个离子基团，间隔，第二个离子基团，和另一个烃尾巴。通过使用刚性间隔物抑制分子内链/链缔合，从而避免自组装成常规胶束结构。通过（a）表面张力、（B）膜平衡法、（c）动态光散射、（d）H-1和Na-23 NMR和（e）吸附染料的光谱变化研究双子的聚集。在双子座的更引人注目的特性中，应该提到以下：（a）较高的临界胶束浓度（B）单分子膜的剥离面积是磷脂的几倍，表明Geminis绝对水平地位于空气/水界面上;和（c）尽管有可能像聚合物一样生长成延伸的链，但仅形成小胶束。有人认为，双子座，特别是较长的链成员，从事自卷曲或亚胶束聚集时，第一次暴露于水。自组装成胶束和吸附在空气/水界面，然后发生在数小时或数天内在23摄氏度，但更迅速地在50摄氏度。光谱数据为亚胶束结构提供了有力的证据。
''Gemini surfactant'' is a name assigned to a family of synthetic amphiphiles possessing, in sequence, a long hydrocarbon chain, an ionic group, a spacer, a second ionic group, and another hydrocarbon tail. Intramolecular chain/chain association was inhibited through the use of rigid spacers, thereby averting self-assembly into conventional micellar structures. Aggregation of the geminis was investigated by (a) surface tension, (b) film-balance methods, (c) dynamic light scattering, (d) H-1 and Na-23 NMR, and (e) spectral changes in an adsorbed dye. Among the more striking properties of geminis, one should cite the following: (a) a higher critical micelle concentration (according to surface tension and NMR) for geminis with two long chains of 16-20 carbons than that for shorter-chain analogs; (b) the lift-off areas in monomolecular films that are several times those of phospholipids, indicating that the geminis lie absolutely horizontally at the air/water interface; and (c) the formation of only small micelles, despite the potential to grow, polymer-like, into extended strands. It is argued that geminis, especially the longer-chain members, engage in self-coiling or submicellar aggregation when first exposed to water. Self-assembly into micelles and adsorption at the air/water interface then take place over hours or days at 23-degrees-C but much more rapidly at 50-degrees-C. Spectral data provide strong evidence for submicellar structures.