Modifying Mechanical Properties Of Silicon Dioxide Using Porous Graphene: Molecular Dynamics Simulations

Graphene or other 2D materials are often used as agents to reinforce engineering structures because they possess extremely high mechanical strength and structural flexibility. This is however not cost effective and the reported enhancement is often limited although the mechanical properties of graphene is often several orders higher than cements or concretes. Defective graphene is mechanically weaker than pristine graphene but stronger than engineering structures, moreover, it is cheaper because the synthesis condition is low. In this work we perform systematic molecular dynamics simulations to evaluate the effect of porous graphene (PG), a type of defective graphene, on reinforcing mechanical properties of silicon dioxide (SiO2) which is the key components of engineering structures. Our results show that PG is mechanically weaker than pristine graphene but stronger than SiO2, therefore, with certain amount of PG encapsulation into SiO2, the mechanical properties can be improved under tensile, shear and compressive loadings, although not as significant as the effective of pristine graphene. The modification mechanism is found to depend both on the intrinsic mechanical properties of GP and the interface induced surface stress redistribution in SiO2. The effects of defect concentration, volume fraction, loading methods and interface roughness are found to be influential on the reinforcing effect. Our findings are expected to offer new strategies for rational design of low-cost but high-strength engineering composite structures.