Molecular Modeling and Mechanics of Acrylic Adhesives on a Graphene Substrate with Roughness

Abstract

Understanding the mechanics of amorphous polymeric adhesives on a solid substrate at the fundamental scale level is critical for designing and optimizing the mechanics of composite materials. Using molecular dynamics simulations, we investigate the interfacial strength between graphene and polyacrylic and discuss how the surface roughness of graphene affects the interfacial strength in different loading directions. Our results show that a single angstrom increase in graphene roughness can lead to almost eight times higher shear strength, and that such result is insensitive to compression. We have also revealed that the graphene roughness has modest effect on tensile strength of the interface. Our simulations elucidate the molecular mechanism of these different effects in different loading conditions and provide insights for composite designs.

Interfacial stress transfer in strain engineered wrinkled and folded graphene

“…Substituting the value of a/λ of wrinkles in the low pre-strained graphene yields a value in good agreement with the theoretical η r obtained at 1.0% strain as shown in figure 9(c) (black dot in figure 10(b)). This validates the geometrical model and suggests that the wrinkled graphene with low pre-strain still generally conforms to the substrate, similar to flat graphene (figures 10(c) and (d)), consistent with the recent observations and predictions [18,24,26,54,55]. However, for flakes with high pre-strain where folds occur (red and blue dots in figure 10(b)), the estimated η r significantly overestimates the measured values due to the occurrence of delamination underneath the folds as indicated by the significantly increased a (figure 9(a)).…”

Wrinkled Few-Layer Graphene as Highly Efficient Load Bearer

“…Previous MD simulations have shown that small deviations from the ideal bonding even at the angstrom scale can affect the mechanical behavior of graphene on polymers by reducing the adhesion energy. 31,32 As mentioned earlier, this is exactly the case for many systems particularly those employing CVD graphene, since in those cases the 2D inclusion is already heavily wrinkled, exhibiting out-of-plane folds which are detrimental as far as stress-transfer is concerned. 33 This case is clearly depicted in Figure 5c, bearing in mind that the size of the islands in-between adjacent folds is below the critical length required for efficient load transfer.…”