Molecular dynamics simulation of mechanical performance of graphene/graphene oxide paper based polymer composites

Highly ordered polymer composites of layered graphene/graphene oxide (GO) sheets, i.e. graphene/GO paper, are attractive candidates for novel structural and functional applications. Here, molecular dynamics simulations are employed to elucidate the structural and mechanical properties of the graphene/GO paper based polymer composites. We find that the large scale properties of these composites are controlled by the conformation and content of polymer molecules within the interlayer galleries. Polymer conformations affect the interlayer spacing, while the polymer content controls the layer-matrix interactions, thereby affecting the elastic modulus of the composites. Additionally, the chemical composition of individual GO sheets also plays a critical role in establishing the mechanical properties of the composites. Specifically, a higher density of oxygen-containing groups leads to the decrease of elastic modulus of individual GO sheets. However, the groups also lead to the increased hydrogen bonds between the GO sheets and polymer molecules, resulting in the corresponding increase in overall stiffness. Our studies suggest the possibility of tuning the properties of graphene/GO paper composites by altering the conformation and content of polymer, as well as the density of functional groups on individual GO sheets.