Molecular dynamic simulation of layered graphene clusters formation from polyimides under extreme conditions

Abstract

The previous experimental study illustrated that a direct laser scribing on polyimide (PI) induced the layered graphene, which opened a new door of producing graphene associated materials. However, underlain conversion mechanism is unknown, especially from theoretical perspectives. In this paper, we performed the molecular dynamics (MD) simulation of this mechanism under extreme conditions of the high pressure and temperature which mimic the ones generated by the laser induction. We investigated this process using the ReaxFF potential in a nanosecond time scale. We found out that at a pressure of ~ 3 GPa and temperature of > 2400 K generated from the NVT processes, the layered graphene clusters were crystallized from PI without metal catalysts, which is consistent with the previous experiment. However, if simulated using the NPT processes with a pressure of 27 MPa, the PI were decomposed into small molecules, and no graphene layers were observed. Furthermore, by analyzing the number of the carbon rings and the pair distribution function of them we quantified the crystallinity of the graphene clusters. Through tracing the emission of the small molecules such as H 2 O, N 2 , H 2 , CO we propose the possible reaction paths for both of the NVT and NPT processes.

UV Laser‐Induced Polyimide‐to‐Graphene Conversion: Modeling, Fabrication, and Application

“…[26] However, the underlying conversion mechanism for this method is still unclear, and the key parameters to ensure high-quality graphene are yet to be identified. A molecular dynamics (MD) simulation study by Dong et al suggests that under extreme conditions of high pressure (≈3 GPa) and temperature (>2400 K), which mimic those generated by the infrared laser induction, it is possible to form crystallized layered graphene clusters from PI without the assistance of metal catalysts; this result is consistent with previous experimental observations; [39] on the other hand, recent work [40,41] show that if UV laser, instead of infrared laser, is used in the conversion process, only very poor quality graphene can be produced, due possibly to the poor absorption of UV light by the carbon source or unoptimized processing conditions.In this study, we investigated in-depth the light-material interaction by developing a reactive MD model to disclose the transient process that leads to LIG formation and identified the critical parameters that govern this process. Following the theoretical prediction, we have experimentally demonstrated that picosecond UV laser processing can also be used to prepare high-quality LIG from PI at ambient conditions.…”

“…However, the underlying conversion mechanism for this method is still unclear, and the key parameters to ensure high‐quality graphene are yet to be identified. A molecular dynamics (MD) simulation study by Dong et al suggests that under extreme conditions of high pressure (≈3 GPa) and temperature (>2400 K), which mimic those generated by the infrared laser induction, it is possible to form crystallized layered graphene clusters from PI without the assistance of metal catalysts; this result is consistent with previous experimental observations; on the other hand, recent work show that if UV laser, instead of infrared laser, is used in the conversion process, only very poor quality graphene can be produced, due possibly to the poor absorption of UV light by the carbon source or unoptimized processing conditions.…”

Direct Semiconductor Laser Writing of Few‐Layer Graphene Polyhedra Networks for Flexible Solid‐State Supercapacitor

“…[8] Therefore, the versatile surface properties of the final carbonaceous materials should be minted during the photothermal reaction and ultrafast cooling. Molecular dynamics (MD) simulation of this direct laser scribing on PI sheets process revealed that extreme conditions of high pressure (≈3 Gp) and high temperature(>2400 K) might be generated by laser induction.…”

Laser‐Induced Graphene: From Discovery to Translation

“…The entire process can be performed in ambient air without any solvents, thereby making it exceedingly attractive for industrial use. This protocol combines the 3D graphene synthesis with writing into a single step process that has stimulated research ranging from fundamental studies on the transformation process to the development of a large variety of engineering applications …”