Interfacial characteristics of a carbon nanotube-polyimide nanocomposite by molecular dynamics simulation

With molecular dynamics simulations, nanocomposites were characterized that are comprised of a polyimide (PI) polymer and carbon nanotubes (CNTs) with the same outer diameter but with one, two, or three walls. The simulations indicate that the PI/CNT interaction is strong, regardless of the number of CNT walls, and that there is some degree of alignment of the PI chains near the CNT interface. As the number of CNT walls increased, the density of PI chains near the CNT interface also increased and the average radius of gyration of the PI chains decreased, and these observations were attributed to changes due to the intertube van der Waals interactions. From simulations of the constant force pullout process of the CNT from the PI matrix, the limiting pullout force was calculated to be higher for the triple-walled CNT than for the single-walled one. The interfacial shear strength of the nanocomposites was also calculated from the pullout energy, and the results indicate that increasing the number of walls is a critical factor for enhancing the interfacial stress transfer during tension.