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

Qian Jiang,Yiping Qiu,Melissa A Pasquinelli,Syamal S Tallury

doi:10.1515/ntrev-2020-0012

Qian Jiang, Yiping Qiu + Show 2 more

Open Access

https://doi.org/10.1515/ntrev-2020-0012

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Abstract

Abstract 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.

Highlights

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
Portions of the PI chains that are within 0.7 nm of the CNT surface are indicated at the bottom of Figure 2, and reveal a few interesting observations at the interface: (1) portions of the PI chains are aligned with the CNT surface in various directions; (2) there is some degree of wrapping of PI chains, not complete wrapping for most of the chains due to both the overall length of the polymer chains and due to confinement effects; and (3) some interchain alignment occurs due to π-π interactions
Since all three systems started with the same initial configuration prior to the equilibration process and the outer CNT wall for all three systems has the same diameter, this observation indicates that the differences in the van der Waals forces that result from multiple walls can have a significant impact on the structure of the PI matrix

Summary

Introduction

Abstract: 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 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. The interfacial shear strength of the nanocomposites was 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

Methods

Results

Conclusion