We use molecular dynamics simulations to study a semidilute, unentangled polymer solution containing well-dispersed, weakly attractive nanoparticles (NP) of size (σ_N) smaller than the polymer radius of gyration R_g. We find that if σ_N is larger than the monomer size the polymers swell, while smaller NPs cause chain contraction. The diffusion coefficient of polymer chains (D_p) and NPs (D_N) decreases if the volume fraction ϕ_N is increased. The decrease of D_p can be well described in terms of a dynamic confinement parameter, while D_N shows a more complex dependence on σ_N, which results from an interplay between energetic and entropic effects. When ϕ_N exceeds a σ_N-dependent value, the NPs are no longer well dispersed and D_N and D_p increase if ϕ_N is increased.

中文翻译：

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聚合物-纳米颗粒复合材料的结构和动力学：纳米颗粒尺寸和体积分数的影响

我们使用分子动力学模拟来研究亚浓，含有良好分散的，弱吸引力的纳米颗粒（NP）的大小（σ非缠结聚合物溶液_Ñ）比的回转聚合物半径小ř_克。我们发现，如果σ _Ñ比单体尺寸，该聚合物溶胀，而较小的NP原因链收缩大。如果体积分数ϕ _N增加，则聚合物链（D _p）和NPs（D _N）的扩散系数降低。D _p的减小可以用动态约束参数很好地描述，而D _N对σ的依赖性更复杂_N，它是能量和熵效应之间相互作用的结果。当φ _Ñ超过σ _Ñ依赖性值时，纳米颗粒不再很好地分散和d _Ñ和d _p增加，如果φ _Ñ增加。