Diminishing Interfacial Effects with Decreasing Nanoparticle Size in Polymer-Nanoparticle Composites
Diminishing Interfacial Effects with Decreasing Nanoparticle Size in Polymer-Nanoparticle Composites
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DOI：
10.1103/physrevlett.121.207801
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发表时间：
2018-11-13
影响因子：
8.6
通讯作者：
Starr, Francis W.
中科院分区：
文献类型：
--
作者：
Emamy, Hamed;Kumar, Sanat K.;Starr, Francis W.
使用分子模拟模型聚合物纳米复合材料在固定的填料加载，我们表明，界面聚合物动力学的影响较小，减少纳米粒子（NP）的大小。然而，玻璃化转变温度T-g对于极小的NP变化显著更多。这种明显矛盾的原因是平均NP间距随着颗粒尺寸的减小而减小。因此，对于足够小的NP，所有聚合物都是有效的界面，导致相对大的T-g位移，即使界面效应较小。对于较大的NP，界面弛豫基本上比有利的NP-聚合物相互作用的基质慢。少数“绑定”聚合物动态地从聚合物基体中分离，并且我们只发现相对于大NP的本体聚合物的T-g的小变化。这些结果被用来组织大量的相关实验数据，我们提出了一个明显的普遍依赖的比例的面到面之间的距离的NP和链的回转半径。
Using molecular simulations on model polymer nanocomposites at fixed filler loading, we show that interfacial polymer dynamics are affected less with decreasing nanoparticle (NP) size. However, the glass transition temperature T-g changes substantially more for an extremely small NP. The reason for this apparent contradiction is that the mean NP spacing decreases with decreasing particle size. Thus, all polymers are effectively interfacial for sufficiently small NPs, resulting in relatively large T-g shifts, even though the interfacial effects are smaller. For larger NPs, interfacial relaxations are substantially slower than the matrix for favorable NP-polymer interactions. The minority "bound" polymer dynamically decouples from the polymer matrix, and we only find small changes in T-g relative to that of the bulk polymer for large NPs. These results are used to organize a large body of relevant experimental data, and we propose an apparent universal dependence on the ratio of the face-to-face distance between the NPs and the chain radius of gyration.