Effects of graphene thickness and length distribution on the mechanical properties of graphene networks: A coarse-grained molecular dynamics simulation

Highlights: • Monolayer graphene networks possess better mechanical properties than bilayer or multi-layer graphene networks. • Graphene bending and slippage dominate mechanical behavior of monolayer graphene networks. • Mechanical properties of networks with Gaussian distributed graphene length is slightly higher. Assembling graphene into three-dimensional (3D) structure while preserving the superior physical properties of graphene have attracted a great deal of attention for its potential applications. Here, to reveal the effects of graphene thickness and length distribution on the mechanical behaviors of graphene networks, molecular dynamics simulations were performed based on a coarse-grained graphene model, which demonstrates that the thickness of graphene layers plays an important role in the mechanical properties of 3D graphene networks. Monolayer graphene is flexible and can be easily crumpled, thus strengthening interaction between different graphene sheets. High strength and modulus can be achieved for monolayer graphene networks both under uniaxial tensile and compressive loading, which is attributed to the combination of out-of-plane deformation of monolayer graphene and inter-graphene slippage. Comparing with the graphene networks with different structure, the networks with Gaussian distributed graphene length shows slightly higher compressive mechanical properties due to the higher density. This work can provide guidelines for the design of graphene networks with better mechanical properties and might promote the application of 3D graphene networks.