Wang Zixuan, Zheng Zijian, Liu Jun, Wu Youping, Zhang Liqun
Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, Beijing 100029, China.
Beijing Engineering Research Center of Advanced Elastomers, Beijing 100029, China.
Polymers (Basel). 2016 Aug 25;8(9):270. doi: 10.3390/polym8090270.
By employing coarse-grained molecular dynamics simulation, we simulate the spatial organization of the polymer-grafted nanoparticles (NPs) in homopolymer matrix and the resulting mechanical performance, by particularly regulating the grafted chain length and flexibility. The morphologies ranging from the agglomerate, cylinder, sheet, and string to full dispersion are observed, by gradually increasing the grafted chain length. The radial distribution function and the total interaction energy between NPs are calculated. Meanwhile, the stress⁻strain behavior of each morphology and the morphological evolution during the uniaxial tension are simulated. In particular, the sheet structure exhibits the best mechanical reinforcement compared to other morphologies. In addition, the change of the grafted chain flexibility to semi-flexibility leads to the variation of the morphology. We also find that at long grafted chain length, the stress⁻strain behavior of the system with the semi-flexible grafted chain begins to exceed that of the system with the flexible grafted chain, attributed to the physical inter-locking interaction between the matrix and grafted polymer chains. A similar transition trend is as well found in the presence of the interfacial chemical couplings between grafted and matrix polymer chains. In general, this work is expected to help to design and fabricate high performance polymer nanocomposites filled with grafted NPs with excellent and controllable mechanical properties.
通过采用粗粒度分子动力学模拟，我们模拟了聚合物接枝纳米粒子（NPs）在均聚物基质中的空间组织以及由此产生的力学性能，特别调节了接枝链的长度和柔韧性。通过逐渐增加接枝链长度，观察到了从团聚体、圆柱体、片层、线状体到完全分散的各种形态。计算了纳米粒子之间的径向分布函数和总相互作用能。同时，模拟了每种形态的应力-应变行为以及单轴拉伸过程中的形态演变。特别是，与其他形态相比，片层结构表现出最佳的机械增强效果。此外，接枝链柔韧性向半柔韧性的变化导致了形态的改变。我们还发现，在接枝链长度较长时，具有半柔性接枝链的体系的应力-应变行为开始超过具有柔性接枝链的体系，这归因于基质与接枝聚合物链之间的物理互锁相互作用。在接枝聚合物链与基质聚合物链之间存在界面化学偶联的情况下，也发现了类似的转变趋势。总的来说，这项工作有望有助于设计和制造填充有接枝纳米粒子的高性能聚合物纳米复合材料，其具有优异且可控的力学性能。
