Dynamics of entangled interfacial polymer layers around nanoparticles determine the linear rheological properties of polymer nanocomposites. In this study, the nonlinear elastic properties of nanocomposites are examined under large-amplitude oscillatory shear (LAOS) flow to reveal the effect of interfacial chemical heterogeneity on the deformation mechanism of polymer-grafted and polymer-adsorbed nanoparticle composites. Adsorbed-poly(methyl methacrylate) (PMMA) layers presented stronger interfacial stiffening and reinforcement than PMMA-grafted layers. Chemical heterogeneities of interfacial layers, provided by polymer-adsorbed and low graft density particles, deformed at smaller strains than the poly(ethylene oxide) (PEO) matrix. Interfaces of loosely bound PMMA and PEO exhibited stiffening at low strains due to the enhanced chain mixing and entanglements. These results demonstrate that chemical and dynamic heterogeneities in interfacial layers have significant importance in designing adaptive polymer nanocomposites for large shear deformation.

中文翻译：

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聚合物纳米复合材料化学不均匀界面层的变形

纳米粒子周围缠结的界面聚合物层的动力学决定了聚合物纳米复合材料的线性流变特性。在这项研究中，在大振幅振荡剪切 (LAOS) 流动下检查纳米复合材料的非线性弹性性能，以揭示界面化学异质性对聚合物接枝和聚合物吸附纳米颗粒复合材料变形机制的影响。与 PMMA 接枝层相比，吸附聚（甲基丙烯酸甲酯）（PMMA）层具有更强的界面硬化和增强作用。由聚合物吸附和低接枝密度颗粒提供的界面层的化学异质性在比聚（环氧乙烷）（PEO）基质更小的应变下变形。由于增强的链混合和缠结，松散结合的 PMMA 和 PEO 的界面在低应变下表现出硬化。这些结果表明，界面层中的化学和动态异质性对于设计用于大剪切变形的自适应聚合物纳米复合材料具有重要意义。