Zhao Jianxi, Deng Shaojun, Liu Jinyan, Lin Cuiying, Zheng Ou
Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350002, China.
J Colloid Interface Sci. 2007 Jul 1;311(1):237-42. doi: 10.1016/j.jcis.2007.02.045. Epub 2007 Mar 23.
The state of water in the reverse micelles of C12-s-C(12).2Br homologues has been investigated by Fourier transform infrared spectroscopy. The results showed that the solubilized water had four states: the quaternary ammonium head-group-bound, the Br--bound, the bulklike, and the free water. With increasing W0, the number of bulklike water per surfactant (nb) rapidly increased, which indicated swelling of the reverse micelle. The number of the head-bound water per surfactant (nN+) gradually increased. This was attributed to a reduction of the interfacial curvature, which permitted more water molecules to associate with the ionic heads of surfactants and also led to a part of n-hexanol being expelled from the interface and thus water filled up. Owing to the existence of n-hexanol in the interface, the head-bound water of the present system was smaller than that of AOT system at the same W0. The number of counterion-bound water per surfactant (nBr-) remained unchanged with W0. This was due to much smaller dissociation of the head of C12-2-C(12).2Br than that of AOT. With increasing s, unchanged nN+ is attributed to the comprehensive effects of enlarged head, which promotes the hydration, increased ionization degree, and reduced size of the water pool. Owing to increased ionization degree, nBr- increases with s.
通过傅里叶变换红外光谱研究了C12-s-C(12).2Br同系物反胶束中的水状态。结果表明，增溶水有四种状态：季铵头基结合水（quaternary ammonium head-group-bound）、Br-结合水（Br--bound）、类本体水（bulklike）和自由水。随着W0的增加，每个表面活性剂的类本体水数量（nb）迅速增加，这表明反胶束发生了膨胀。每个表面活性剂的头基结合水数量（nN+）逐渐增加。这归因于界面曲率的降低，这使得更多水分子能够与表面活性剂的离子头缔合，也导致一部分正己醇从界面排出，从而水得以填充。由于界面中存在正己醇，在相同W0下，本体系的头基结合水比AOT体系的少。每个表面活性剂的反离子结合水数量（nBr-）随W0保持不变。这是因为C12-2-C(12).2Br头基的离解比AOT小得多。随着s的增加，nN+不变归因于头基增大的综合影响，这促进了水合作用、增加了电离度并减小了水池尺寸。由于电离度增加，nBr-随s增加。
