Vacancy-induced interfacial crosslinking in graphene/carbon nanotube composites and its influence on mechanical behaviors: A molecular dynamics simulation

Although defects such as vacancies may degrade the in-plane mechanical properties of graphene and carbon nanotube (CNT), they may also promote interfacial crosslinking and load transfer, and thus enhance the mechanical behavior of graphene- and CNT-based composites. The balance between these effects is crucial for optimizing the design of graphene- and CNT-based composites. Herein, molecular dynamics simulations were constructed to unravel the effect of vacancy-induced interfacial crosslinking on the mechanical behaviors of graphene/CNT composites. Higher defect concentrations led to a higher density of sp³ C–C bonds at the interface, which reduced the tensile failure stress but increased the tensile failure strain. Meanwhile, the layer-by-layer failure transformed into a brittle failure. During compressive loading, the composites tended to buckle in the lower defect concentration range (<0.5 %) but exhibited outstanding buckling resistance at higher defect concentrations (5 %, 10 %). Shear loading led to wrinkling, and deformation instability was suppressed at the higher defect concentration, and all the composites demonstrated a layer-by-layer failure mode. Furthermore, the composites with a higher concentration of defects demonstrated excellent recoverable behavior during compressive loading. The results provide insights into the interface-dominated performance of graphene/CNT composites and help guide their design and fabrication.