Molecular dynamics simulation of temperature and defect-induced change of the mechanical properties of PBCF-graphene nanosheet

Abstract

This study employs Molecular Dynamics (MD) simulations to investigate the mechanical properties of a Poly-Butadiene-Cyclooctatetraene-Framework (PBCF) graphene nanosheet, a two-dimensional sp² hybridized honeycomb carbon allotrope. The simulations considered the effects of temperature and defects on the nanosheets' behavior. The mechanical properties examined include the stress-strain behavior, Young's modulus, ultimate stress, as well as stress distribution within nanosheet prior to final fracture during tensile loading. PCBF-graphene nanosheets have a Young's modulus of 841.76 GPa (armchair) and 753.15 GPa (zigzag), with higher stiffness in the armchair orientation. The material behaves brittle in the zigzag direction and ductile in the armchair, highlighting its anisotropic mechanical properties. Temperature significantly impacts mechanical properties, with both Young's modulus and ultimate stress decreasing as temperature rises. Zigzag nanosheets are more sensitive to these changes. Initially, the armchair PBCF-graphene nanosheet has higher Young's modulus, but at elevated temperatures, the zigzag nanosheet surpasses it.