Molecular simulation of the interlayer structure and the mobility of alkyl chains in HDTMA+/montmorillonite hybrids
Molecular simulation of the interlayer structure and the mobility of alkyl chains in HDTMA+/montmorillonite hybrids
复制标题
DOI：
10.1021/jp0517495
复制
发表时间：
2005-07-14
影响因子：
3.3
通讯作者：
Gerard, JF
中科院分区：
文献类型：
--
作者：
He, HP;Galy, J;Gerard, JF
分子模拟技术被用来找到的基础上的能量最小的有机粘土的基底间距，使用正则NVT系综。然后，基于层间原子密度分布，探讨了烷基链的层间结构和迁移率。除了基本的横向单层结构外，还观察到了横向双层结构和部分伪三层结构，以及两种基本横向模型之间的过渡结构。后者提供了一个很好的解释，在16埃的XRD图案在文献中的反射。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。模拟结果表明，随着插层表面活性剂含量的增加，受限烷基链的分子迁移率从侧向单层到侧向双层逐渐减小。这与实验结果一致。此外，我们的模拟表明，烷基链的流动性强烈依赖于表面活性剂的安排，而不是表面活性剂的堆积密度。
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 angstrom 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.