接枝在六面体和球形表面的聚电解质刷相行为对比研究

A comparison of the phase behavior of polyelectrolyte brushes grafted on hexahedral and spherical surfaces

采用分子动力学方法模拟了接枝在六面体和球形纳米粒子表面的聚电解质刷.研究了3价抗衡离子条件下,2种形状的聚电解质刷在不良溶剂中的相行为.通过对比三维相图、二维等密度图和刷高,分析讨论了2种刷的状态.结果表明,接枝表面曲率均匀与否,对其上的聚电解质刷相行为有很大影响.计算了聚电解质刷的链间关联函数,同时统计了3价抗衡离子的链内和链间关联作用,定量证明曲率不均匀会增强链间的关联效应,导致2种聚电解质刷的相行为出现差异.

Polyelectrolyte brushes grafted on the surface of hexahedron and spherical nanoparticles were simulated here by molecular dynamics. The phase behavior of two types of polyelectrolyte brushes in poor solvent and trivalent counterions was studied. Three-dimensional phase diagrams,two-dimensional isodensity contours and brush height were compared to examine the state of these two types of brushes. Uniformity in surface curvature was found to have major influence on their phase behavior. The inter-chain correlation functions were calculated,intra-chain and inter-chain correlation effects of trivalent counterions were also investigated. These data prove quantitatively that nonuniform curvature enhances inter-chain correlation effect, leading to the difference in phase behavior of the two polyelectrolyte brushes.