Department of Chemical Engineering and Materials Science, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe-shi, Kyoto 610-0321, Japan.
J Chem Phys. 2009 Nov 7;131(17):174707. doi: 10.1063/1.3254517.
Interfacial crystallization, such as surface crystallization in solution (solid-liquid) and liquid-liquid crystallization, gives us an asymmetric reaction field and is a technique for morphology control of crystals. In the liquid-liquid crystallization, the concentration distribution of solute ions and solvent molecules at the liquid-liquid interface directly relates to nucleation, crystal growth, and crystal morphology. Nonequilibrium molecular dynamics (MD) simulations have been performed at interfaces in NaCl solution/1-butanol and KCl solution/1-butanol system in order to clarify diffusion behavior of solute ions and solvent molecules. As simulation results, the hydrated solute ions were dehydrated with the diffusion of water from solution phase into 1-butanol phase. The different dehydration behaviors between NaCl and KCl solution can be also obtained from MD simulation results. Aggregated ions or clusters were formed by the dehydration near the solution/1-butanol interface. By comparison on the normalized number of total solute ions, the size and number of generated cluster in KCl solution/1-butanol interface are larger than those in the NaCl system. This originates in the difference hydration structures in the each solute ion.
界面结晶，例如溶液（固-液）中的表面结晶和液-液结晶，为我们提供了一个不对称的反应场，是控制晶体形态的一种技术。在液-液结晶中，溶质离子和溶剂分子在液-液界面的浓度分布直接关系到成核、晶体生长和晶体形态。为了阐明溶质离子和溶剂分子的扩散行为，在 NaCl 溶液/1-丁醇和 KCl 溶液/1-丁醇体系的界面进行了非平衡分子动力学（MD）模拟。作为模拟结果，水合溶质离子随着水从溶液相扩散到 1-丁醇相而脱水。还可以从 MD 模拟结果中得到 NaCl 和 KCl 溶液之间不同的脱水行为。在溶液/1-丁醇界面附近脱水形成聚集离子或团簇。通过比较总溶质离子的归一化数量，可以看出 KCl 溶液/1-丁醇界面生成的团簇的大小和数量大于 NaCl 体系。这源于每个溶质离子中不同的水合结构。
