Effect of ionic surfactants on the iridescent color in lamellar liquid crystalline phase of a nonionic surfactant
Effect of ionic surfactants on the iridescent color in lamellar liquid crystalline phase of a nonionic surfactant
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DOI：
10.1016/j.jcis.2006.09.070
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发表时间：
2007-01-15
影响因子：
9.9
通讯作者：
Tsujii, Kaoru
中科院分区：
文献类型：
--
作者：
Chen, Xinjiang;Mayama, Hiroyuki;Tsujii, Kaoru
非离子表面活性剂衣康酸正十二烷基甘油酯（DGI）在水中自组装成具有亚微米间距的双层膜，并显示出美丽的彩虹色。离子型表面活性剂对该虹彩体系有很强的影响。有趣的是，我们发现DGI和离子型表面活性剂混合后，虹彩颜色随时间而变化，平衡状态下的颜色随离子型表面活性剂的浓度变化很大。颜色随时间变化的原因是DGI与离子型表面活性剂混合后聚集体结构发生了变化。首次发现，即使表面活性剂的总浓度几乎恒定，通过改变所加入的离子表面活性剂的浓度，该非离子体系的虹彩颜色也可以从红色变为深蓝色。平衡状态下虹彩色的蓝移如此之大，用目前应用于这一现象的普通波动理论还不能完全解释。通过增加离子表面活性剂的浓度，平坦的层状片趋于弯曲，以形成分离的洋葱样和/或髓磷脂样结构。这些层状体系的分离结构导致双层膜之间的间距减小，因为这些结构之间必然会出现一些空位。(c)2006年爱思唯尔公司All rights reserved.
A nonionic surfactant, n-dodecyl glyceryl itaconate (DGI), self-assembles into bilayer membranes in water having a spacing distance of submicrometer in the presence of small amounts of ionic surfactants, and shows beautiful iridescent color. Ionic surfactants have strong effects on this iridescent system. We have interestingly found that the iridescent color changes with time after mixing DGI and ionic surfactants and the color in equilibrium state changes greatly with concentration of the ionic surfactants. The time-dependent color change results from the transformation of DGI aggregate structure after being mixed with ionic surfactant. It is first found that the iridescent color of this nonionic system can be changed from red to deep blue by altering the concentration of ionic surfactants added even though the total concentration of surfactant is almost constant. Such large blue shift of the iridescent color in equilibrium state cannot be fully explained by the ordinary undulation theory applied so far for this phenomenon. The flat lamellar sheets tend to curve by increasing the concentration of ionic surfactants to form separated onion-like and/or myelin-like structures. These separated structures of lamellar system result in the decrease of spacing distance between bilayer membranes because some vacant spaces necessarily appear among these structures. (c) 2006 Elsevier Inc. All rights reserved.