Department of Chemical Engineering, Tennessee Technological University, Cookeville, Tennessee 38505, USA.
J Chem Phys. 2019 Jan 28;150(4):044905. doi: 10.1063/1.5084146.
Molecular dynamics simulations are used to study the diffusion of polymer-grafted nanoparticles (PGNPs) in polymer. The diffusivity of PGNPs in the homopolymer matrix is investigated as a function of graft length and grafting density, and it is compared to that of bare nanoparticles with comparable effective size. Our results indicate that, in addition to the increase in the effective size of PGNPs due to grafting, the interpenetration of matrix polymers into the grafted layer also plays an important role in the mobility of PGNPs. In systems consisting of both PGNPs and bare particles, the spatial arrangement of the bare particles was found to be having a significant influence on the mobility of PGNPs. At low graft length and high grafting density, the matrix chains dewets the grafted layer, due to autophobic dewetting, creating a sharper interface between the matrix and the grafted layer. The bare particles then migrate to the interface creating a barrier around the PGNPs that hinders the matrix-graft interpenetration and results in the higher mobility of PGNPs. Our results emphasize the importance of polymer-particle interface on the dynamic properties of polymer nanocomposites.
采用分子动力学模拟研究了聚合物接枝纳米粒子（PGNPs）在聚合物中的扩散。研究了接枝长度和接枝密度对 PGNPs 在均聚物基体中扩散系数的影响，并与具有可比有效尺寸的裸纳米粒子进行了比较。结果表明，除了由于接枝导致 PGNPs 的有效尺寸增加外，基体聚合物渗透到接枝层中也对 PGNPs 的迁移率起着重要作用。在同时包含 PGNPs 和裸粒子的体系中，发现裸粒子的空间排列对 PGNPs 的迁移率有显著影响。在接枝长度低和接枝密度高的情况下，由于自憎去湿，基体链会从接枝层上脱湿，在基体和接枝层之间形成更明显的界面。然后，裸粒子迁移到界面上，在 PGNPs 周围形成一个障碍，阻碍了基体-接枝的相互渗透，从而导致 PGNPs 的迁移率更高。研究结果强调了聚合物-粒子界面对聚合物纳米复合材料动态性能的重要性。
