Fatigue Behavior of Polymer Encapsulated Graphene to Mitigate Interfacial Fatigue Damage

Abstract

In applications such as flexible electronic devices, graphene, and other 2D materials are frequently in contact with stretchable polymeric substrates. The interface between 2D materials and polymers is dominated by weak van der Waals forces and can eventually degrade due to the frequent dynamic mechanical loads that these devices experience. This can lead to significant local delamination and shear fracture of the 2D materials. Using the polydimethylsiloxane (PDMS) encapsulation method, it is shown that the damage in graphene is significantly mitigated when it is capped during dynamic loading. To track the spread of damage in both encapsulated and nonencapsulated graphene, in situ, cyclic loading is performed. The fundamental process driving this substantial reduction in damage propagation in the 2D lattice is explained by the conventional shear lag model. It is also observed that softer PDMS substrate and capping layer completely mitigate the fatigue damage in graphene for 100 cycles at 10% applied fatigue strain.