The Rouse dynamics of polymer chains in model nanocomposite polyethylene oxide/silica nanoparticles (NPs) was investigated using quasielastic neutron scattering. The apparent Rouse rate of the polymer chains decreases as the particle loading increases. However, there is no evidence of an immobile segment population on the probed time scale of tens of ps. The slowing down of the dynamics is interpreted in terms of modified Rouse models for the chains in the NP interphase region. Thus, two chain populations, one bulk-like and the other characterized by a suppression of Rouse modes, are identified. The spatial extent of the interphase region is estimated to be about twice the adsorbed layer thickness, or ≈2 nm. These findings provide a detailed description of the suppression of the chain dynamics on the surface of NPs. These results are relevant insights on surface effects and confinement and provide a foundation for the understanding of the rheological properties of polymer nanocomposites with well-dispersed NPs.

中文翻译：

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分散良好的聚合物纳米复合材料中颗粒表面链段动力学的抑制


使用准弹性中子散射研究了纳米复合材料聚环氧乙烷/二氧化硅纳米粒子（NP）模型中聚合物链的劳斯动力学。聚合物链的表观劳斯速率随着颗粒负载量的增加而降低。然而，在数十皮秒的探测时间尺度上，没有证据表明存在不动的片段群体。动力学减慢可以根据 NP 间相区域链的改良劳斯模型来解释。因此，鉴定出两个链群，一个是块状的，另一个以劳斯模式抑制为特征。相间区域的空间范围估计约为吸附层厚度的两倍，即约 2 nm。这些发现详细描述了纳米颗粒表面链动力学的抑制。这些结果是对表面效应和限制的相关见解，并为理解具有良好分散的纳米粒子的聚合物纳米复合材料的流变特性奠定了基础。