AVS 64th International Symposium & Exhibition
    2D Materials Focus Topic Thursday Sessions
       Session 2D-ThP

Paper 2D-ThP20
Effect of Stacking Orientation and Sag on the Strength and Fracture of Graphene Oxide

Thursday, November 2, 2017, 6:30 pm, Room Central Hall

Session: 2D Materials Poster Session
Presenter: Teng Cui, University of Toronto, Canada
Authors: T. Cui, University of Toronto, Canada
C.H. Cao, University of Toronto, Canada
S. Parambath Mundayodan, University of Toronto, Canada
Y. Sun, University of Toronto, Canada
T. Filleter, University of Toronto, Canada
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One great challenge in translating the extraordinary mechanical properties of isolated 2D materials to impact real applications is to understand, and bridge the gap, between monolayer and multilayer properties. Bilayer films, as the most fundamental step towards this challenge, require systematic study to unveil the interaction between layers and elucidate the effect on mechanical behavior. Here, bilayer graphene oxide (GO) with different crystalline stacking orientation and sag conditions will be presented, and the resulting effect on the material strength and fracture will be discussed in detail.

Highly oxidized bilayer GO films were prepared on perforated substrates by a solution-based method, from which different interlayer crystalline stacking angle and sagging depth were obtained and characterized. Atomic force microscopy-based mechanical testing revealed higher strength of aligned (small stacking angle) bilayers as compared to misaligned (large stacking angle) counterparts. Further transmission electron microscopy analysis of fracture surface revealed through-film fracture for the aligned case and individual layer cracking for the misaligned case, casting light on the origin of the strength discrepancy. In addition, the suspended GO films present different sagging depth, which in turn is found to effect the load carrying capacity and the fracture behavior significantly. Our results demonstrated that bilayer GO with ~165 nm sag doubles the fracture force as compared to ~ 40 nm sag. A deeper understanding of the configurational effect, e.g., stacking orientation and sagging, on the mechanical behavior will better facilitate engineering GO for various applications at different size scales.