Understanding the graphene-polymer interfacial mechanical behavior via coarse-grained modeling

Understanding the interfacial behavior of graphene-polymer nanocomposite is a long-standing endeavor to gain deep insight into the mechanical properties of engineered structural materials. In this study, we implement the ‘hard’ cutoff scheme to develop a 4-1 mapping coarse-grained graphene (CGGr) model and the corresponding CG potential TersoffCG(4-1), which faithfully reproduces the honeycomb structure (bond length and angle) and mechanical properties of the graphene sheet compared to experimental results. Taking the poly(methyl methacrylate) (PMMA) and graphene sheet as a representative composite system, we establish a predictive CG modeling framework to study the interfacial behavior at a molecular level. By performing the rate-dependent interfacial separation simulations, our results reveal that lower separation velocity and thicker flexible layer can facilitate the craze fibrils formation and further enhance the toughness of the composite, which attribute to the adequate response of polymer to the graphene under lower velocity and more polymers that potentially to form fibrils under thicker flexible layer. Our work demonstrates the efficacy of TersoffCG(4-1) potential in understanding the interfacial mechanical behavior of graphene-polymer nanocomposite, offering an effective modeling strategy for performance improvement by designing the interfaces.