Interfacial mechanical properties of graphene on randomly rough PET substrate surface: A molecular dynamics study

In this work, molecular dynamics (MD) simulations are performed to create a series of polyethylene terephthalate (PET) substrates with random roughness, and the morphological characteristics and interfacial bonding of graphene on the real rough PET surface are first simulated. The results show that the interfacial mechanical behavior of graphene freely adhered to the PET roughness is influenced by the surface profile. Besides causing the nonconformal contact, the rough surface hinders the propagation of bending waves from the graphene corner regions during the adhesion and weakens their overlap. The increased surface roughness weakens interfacial adhesion and inhibits interfacial sliding, leading to the formation of larger morphological defects such as wrinkles. Furthermore, the measurement of the interfacial adhesion energy of graphene/PET substrate is achieved by the shaft loaded blister test (SLBT), which for the first time is used to simulate the interfacial debonding of graphene on rough PET surfaces. For low surface roughness, interfacial adhesion dominates the debonding behavior and the blister boundary preferentially extends along the interfacial defect area. For high surface roughness, the increasingly serious non-conformal contact makes the blister more likely to instability and enter the stage where normal and shear interactions are coupled.