关键词: 核-壳结构, 聚合物, 纳米复合材料, 粗粒化, 分子模拟, 自组装膜

Abstract:

Based on the Martini force field, the structure of Pluronic block copolymer on the hydrophobic nano-surface self-assembled film was studied by coarse-grained molecular dynamics simulation. The effect of structure of Pluronic copolymer on the self-assembled monolayer film structure is studied systematically. As simulation results show the core-shell structure of polymer-nanoparticle composites were formed whose core originates from nanoparticle while their shell is composed with Pluronic copolymer. The concentration and structure of Pluronic copolymers have a significant influence on the core-shell structure. At lower concentration, a completely covered film was observed with crimp configuration of ethylene oxide (EO) blocks, meanwhile layered film covered on the NP surface. With further rise in the concentration, star-shaped films with stretching configuration of EO blocks were formed. The thickness of shell-layer increases as increasing the relative molecular weights of polymers. Moreover, Pluronic copolymers revealed a special assembled pattern on a NP surface: transform from “S-shaped” to “W-shaped” or “U-shaped” as increasing the molar ratio of propylene oxide (PO). This result may be caused by the fact that limited hydrophobic NP surface can t provide enough adsorption sites as increasing the polymer concentration.

Key words: core-shell structure, polymer, nanoparticle composites, coarse-graining, molecular simulations, self-assembled film