State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China.
School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, 230026, P. R. China.
Macromol Rapid Commun. 2024 Jun;45(12):e2400019. doi: 10.1002/marc.202400019. Epub 2024 Apr 5.
Using molecular dynamics simulations, this study investigates the equilibrium properties and flow behaviors of entangled polymer nanoparticle composites (PNCs) within a nanotube. The results show that the density distribution of nanoparticles (NPs), displacement of polymer chains and NPs, and the moduli of PNCs remain relatively unaffected when NP volume fractions (Φ) ≤0.10. However, the flow behavior of entangled PNCs deviates from the ideal parabolic profile seen in unentangled PNCs, displaying plug-like flow characteristics with a significant platform region, indicating the presence of shear bands. Interestingly, entangled PNCs at intermediate Φ values undergo a significant alteration in NP distribution under steady flow, resulting in notable NP aggregation. At Φ = 0.30, a distinct change in the static structure of PNCs occurs, reducing the equilibrium distance between neighboring NPs. Consequently, the motion of both polymer chains and NPs becomes restricted, leading to an increase in the moduli of PNCs resembling solid-like behavior. Additionally, the entangled PNCs experience a complete absence of flow, indicating the entry into a jamming state. This study contributes to the understanding of PNCs flow behavior and provides insights into fundamental aspects and practical implications of PNCs.
本研究通过分子动力学模拟，考察了纳米管中缠结聚合物-纳米颗粒复合材料（PNC）的平衡性质和流动行为。结果表明，当纳米颗粒体积分数（Φ）≤0.10 时，纳米颗粒（NPs）的密度分布、聚合物链和 NPs 的位移以及 PNC 的模量基本保持不变。然而，缠结 PNC 的流动行为偏离了未缠结 PNC 中理想的抛物线轮廓，呈现出塞流特征，且具有显著的平台区域，表明存在剪切带。有趣的是，在中等Φ值下，缠结 PNC 在稳态流动下经历了 NP 分布的显著变化，导致明显的 NP 聚集。在 Φ = 0.30 时，PNC 的静态结构发生明显变化，降低了相邻 NPs 之间的平衡距离。结果，聚合物链和 NPs 的运动都受到限制，导致 PNC 的模量增加，表现出类似固态的行为。此外，缠结 PNC 完全停止流动，表明进入了堵塞状态。本研究有助于理解 PNC 的流动行为，并为 PNC 的基础方面和实际应用提供了深入的认识。
