Effects of graft locations on dispersion behavior of polymer-grafted nanorods: A molecular dynamics simulation study

X Li and HL Kang and JX Shen, POLYMER, 211, 123077 (2020).

DOI: 10.1016/j.polymer.2020.123077

In this paper, we present the effects of graft locations on the dispersion behavior of polymer-grafted nanorods using molecular dynamics simulations. Four graft locations of chains on nanorods, i.e., end- grafted, quarter grafted, middle-grafted and uniformly grafted, are specially designed, and the effects of graft locations are examined in both sparsely grafted case and densely grafted case. Simulation results show that the end-grafted nanorods exhibit the poorest dispersion in the matrix, whilst the body-grafted (quarter-grafted and middle grafted) ones show the best dispersion. At low grafting density in the mushroom regime, the middle-grafted disperse slightly better than the quarter- grafted, whereas at high grafting density in the brush regime, the situation is reversed. By analyzing the conformations of graft chains (mushroom height and brush height) and the behavior of grafted nanorods, it is inferred that the inter-rod cohesive energy provides a great contribution to the dispersion, as reflected by the significant role of the center region of nanorods. In general, a dense and wide coverage of the center/middle region of nanorods by graft chains can effectively improve the nanorod dispersion. This work is expected to provide some guidance on controlling and improving the dispersion of nanorods in polymer nanocomposites.

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