It is known that most polymers exhibit poor interfacial compatibility with graphene sheets. Modification of graphene's surface by functionalization with small polymer chains from the same building blocks as the matrix polymer improves the compatibility of graphene in polymeric materials. In this paper, the mechanical behaviour of polyethylene glycol (PEG) nanocomposites with graphene grafted with polymeric chains under tensile and compression is investigated using molecular dynamics. The influence of the functional groups (-NH and –OH) that bond the polymer chain to graphene is analysed. It is found that the system containing the –NH functional group showed lower mechanical properties than the system containing the –OH functional group. The mechanical properties of five PEG-nanocomposites are investigated: PEG/G, PEG/GNH-1PEG-S, PEG/GNH-2PEG-L, PEG/GNH-1PEG-S-NH, PEG/GO-1PEG-S. The radius distribution function values and the variation of interfacial interaction energy are also examined. It is shown that functionalization of the graphene sheet increases the magnitude of the interaction energy, and it also reveals higher adhesion between graphene surface and PEG matrix. It is found that the mechanical properties of PEG are mostly improved in the longitudinal direction (reinforcement up to 43 %). Despite the high interaction between the nanofiller and PEG matrix, the low intrinsic properties of the nanofiller, namely Young's modulus, as well as the rupture of the graphene sheet during the deformation process deteriorated the mechanical properties of the nanocomposite. The presence of polymeric chains grafted to graphene improves the adhesion between the graphene surface and the polymeric matrix but decreases its mechanical properties.

中文翻译：

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利用分子动力学对聚合物接枝石墨烯 PEG 纳米复合材料进行机械表征

众所周知，大多数聚合物与石墨烯片的界面相容性较差。通过使用与基体聚合物相同的结构单元的小聚合物链进行官能化来改性石墨烯的表面，提高了石墨烯在聚合物材料中的相容性。在本文中，利用分子动力学研究了石墨烯接枝聚合物链的聚乙二醇（PEG）纳米复合材料在拉伸和压缩下的机械行为。分析了将聚合物链与石墨烯键合的官能团（-NH和-OH）的影响。结果发现，含有-NH官能团的体系表现出比含有-OH官能团的体系更低的机械性能。研究了五种 PEG-纳米复合材料的机械性能：PEG/G、PEG/GNH-1PEG-S、PEG/GNH-2PEG-L、PEG/GNH-1PEG-S-NH、PEG/GO-1PEG-S。还检查了半径分布函数值和界面相互作用能的变化。结果表明，石墨烯片的功能化增加了相互作用能的大小，并且还揭示了石墨烯表面和 PEG 基质之间更高的粘附力。结果发现，PEG的机械性能大部分在纵向上得到改善（补强高达43%）。尽管纳米填料和PEG基质之间存在高度相互作用，但纳米填料的低固有性能（即杨氏模量）以及变形过程中石墨烯片的破裂使纳米复合材料的机械性能恶化。接枝到石墨烯上的聚合物链的存在改善了石墨烯表面和聚合物基体之间的粘附力，但降低了其机械性能。