Mechanical behavior and failure mechanism of multilayer graphene oxides with various oxygen contents and functional types: A ReaxFF molecular dynamics simulation

• Graphene oxide mechanical property optimization method. • Mechanical failure mechanism and fracture process of graphene oxide. • Defect growth mechanism of graphene oxide stretching process. • Effect of internal and external factors on the mechanical properties of GO. • Effect of functional groups on the mechanical properties of GO. An in-depth understanding about the failure mechanism of graphene oxide and its relationship with structure and temperature is essentially important to improve the mechanical properties of graphene oxides. In this work, a series of comparison groups have been established to investigate the effects of oxygen-containing functional group density, the number of layers, temperature, and hydroxyl to epoxy group ratio on the mechanical properties of monolayer and multilayer graphene oxides through ReaxFF molecular dynamics simulations. It is demonstrated that the position of functional group distribution plays a decisive role in the mechanical properties of graphene oxide. Meanwhile, the active thermal motion of atoms at high temperatures leads to a more fracture-prone structure, but the multilayer graphene oxide is less sensitive to temperature compared to monolayer graphene oxide. In addition, the structure with more hydroxyl groups has better mechanical properties because the distortion energy of the carbon skeleton caused by hydrogen groups is much smaller than that of epoxy groups. This study provides directions and possibilities for the optimization of the mechanical properties of graphene oxide.