▎ 摘　　要

A nonequilibrium deformation technique based on the dissipative particle dynamics is employed to investigate the mechanical properties of polymer nanocomposites reinforced by graphene-based nanosheets. Hierarchically packed network structure, (small-length-scale 2D network structure of graphene nanosheets)-in-(large-length-scale 3D network structure of homogeneously dispersed graphene nanosheets), is observed, which plays an important role in governing the mechanical properties of polymer nanocomposites. The improvements in tensional modulus over near polymer bulk (n-P) are about 23% and 61% for polymer/pristine-graphene blends (P/n-Gr) and polymer/polymer-grafting-graphene nanocomposites (P/g-Gr), respectively. In addition to higher tensile strength, the P/g-Gr also exhibit higher tensile strength and yield strength. The strain hardening behaviors at larger deformation are discovered in the polymer/polymer-grafting-graphene nanocomposites when the polymer length is relatively larger, which does not appear in n-P and P/n-Gr. It is further found that the strain hardening behaviors mainly benefit from the stretching behaviors of the polymers grafting to graphene nanosheets. The results reveal the principles of diverse mechanical properties for polymer nanocomposites reinforced by graphene-based nanosheets and may provide useful information for preparing polymer nanocomposites with excellent performance.