Abstract:

The effect of dispersant on the nanoparticle (NP) dispersion in liquid is significantly affected by solution environment. This article uses coarse-grained molecular dynamics simulation methods to study the effects of three solution environmental factors, including pH, temperature and dispersant concentration, on the dispersion stability of liquid nanoparticle systems containing dispersants. It was found that the dispersion effect of dispersant on NPs mainly depends on two aspects, i.e., the adsorptions of dispersant molecules on the NP surface and the aggregations between the dispersant molecules. Through the synergistic action of these two aspects, the dispersant can achieve effective dispersion of NPs. In terms of the mechanisms affecting the NPs dispersion, dispersant concentration affects the relative quantity of dispersant molecules adsorbed on the NP surface and connected with each other forming aggregates; different pH induces the dispersant molecules hydrolyze and modify themselves from electroneutral into electriferous structure in different degree; and temperature affects the stability of connections between dispersant molecules, as well as between dispersant molecule and other individuals in liquid. The above results provide theoretical basis for the control on the dispersion stability of NP liquid system.

Key words: nanoparticles, dispersant, stability, kinetic theory, molecular dynamics simulation of coarse-grained

摘要：

分散剂对纳米颗粒的分散效果受溶液环境影响显著。借助粗粒化分子动力学模拟方法，研究了酸碱度、温度及分散剂浓度三个溶液环境因素对含有分散剂的液相纳米颗粒体系分散稳定性的影响。发现分散剂对纳米颗粒的分散性能主要取决于分散剂在纳米颗粒表面的吸附以及分散剂之间的聚集这两个因素，通过两个因素的协同作用实现对纳米颗粒的有效分散。在影响纳米颗粒分散的机制上，分散剂浓度影响吸附于纳米颗粒表面及相互连接形成聚集体的分散剂的相对数量；不同酸碱度会诱导分散剂水解为不同带电性质的改性结构体；温度影响分散剂之间以及分散剂与其他个体之间的连接稳定性。研究可为液相纳米颗粒体系分散稳定性控制提供理论依据。

关键词: 纳米粒子, 分散剂, 稳定性, 动力学理论, 粗粒化分子动力学模拟