He Hongping, Galy Jocelyne, Gerard Jean-François
Laboratory of Macromolecular Materials/IMP, UMR CNRS 5627, INSA Lyon, Bat. Jules Verne, 20 Avenue A. Einstein, 69621 Villeurbanne Cedex, France.
J Phys Chem B. 2005 Jul 14;109(27):13301-6. doi: 10.1021/jp0517495.
Molecular simulation techniques are used to find the basal spacing of organoclay on the basis of the energy minimum, using the canonical NVT ensemble. Then, the interlayer structure and mobility of alkyl chains are explored based on the interlayer atomic density profiles. Besides the basic lateral-monolayer arrangement, lateral-bilayer accompanied by partial a pseudo-trilayer and a transition structure between the two basic lateral models are observed. The later provides an excellent explanation about the reflection at 16 angstroms on XRD patterns in the literature. The atomic density profiles reveal that nitrogen atoms show stronger layering behavior than carbon atoms do. Our simulation demonstrates that the molecular mobility of the confined alkyl chains decreases from lateral-monolayer to lateral-bilayer with the increase of the intercalated surfactant. This is in accordance with the suggestion deduced from experiments. Furthermore, our simulation indicates that the mobility of the alkyl chains strongly depends on the surfactant arrangement rather than the surfactant packing density.
采用分子模拟技术，利用正则NVT系综，基于能量最小值来确定有机黏土的基面间距。然后，根据层间原子密度分布，探究烷基链的层间结构和流动性。除了基本的单层横向排列外，还观察到了伴随部分伪三层的双层横向排列以及两种基本横向模型之间的过渡结构。后者对文献中XRD图谱上16埃处的反射给出了很好的解释。原子密度分布表明，氮原子比碳原子表现出更强的分层行为。我们的模拟表明，随着插层表面活性剂的增加，受限烷基链的分子流动性从单层横向排列到双层横向排列逐渐降低。这与从实验得出的推测一致。此外，我们的模拟表明，烷基链的流动性很大程度上取决于表面活性剂的排列，而非表面活性剂的堆积密度。
