Molecular dynamics simulation of the electrical conductive network formation of polymer nanocomposites with polymer-grafted nanorods

Grafting chains on the surface of a filler is an effective strategy to tune and control the filler conductive network, which can be utilized to fabricate polymer nanocomposites (PNCs) with high electrical conductivity. In this work, by employing the coarse-grained molecular dynamics simulation, we investigated the effect of polymer-grafted nanorods (NRs) on the conductive probability of PNCs in the quiescent state or under the shear field for different volume fractions of the NRs. The local order structure of the NRs aggregating in the matrix is gradually broken down, and the dispersion state of the NRs improves with increasing grafting density. However, at high grafting densities, the uniform dispersion of the NRs leads to a large NR-NR distance. As a result, the conductive probability first increases and then decreases with the increase of the grafting density. Under the shear field, the conductive probability shows a continuous increase with the grafting density. Compared with that in the quiescent state, the decrease or the increase of the conductive probability depends on the grafting density under the shear field. In particular, the smallest change in the percolation threshold appears at the highest grafting density, which reflects the high conductive stability. In addition, the topological structure of the conductive network nearly remains unchanged with the length of the grafted chain. Finally, compared with the strong attractive interaction between grafted chains and free chains, weakly repulsive interactions can effectively enhance the conductive probability.